tag:theconversation.com,2011:/uk/topics/telescope-2325/articlesTelescope – The Conversation2024-03-26T17:25:44Ztag:theconversation.com,2011:article/2252412024-03-26T17:25:44Z2024-03-26T17:25:44ZPhotographing the eclipse? You’ll join a long history of people seeking proof of experience<p>If you are <a href="https://www.cbc.ca/news/canada/hamilton/eclipse-day-planning-1.7147091">one of the millions planning to view</a> the total solar eclipse on April 8, there is a good chance that you will take pictures of your experience. </p>
<p>And, like many before you, afterwards you may find that those pictures don’t measure up to your expectations, experiences and memories of viewing the eclipse.</p>
<p>We offer some technical tips for eclipse photography, but we also consider why so many of us are drawn to photograph these kinds of collective moments of awe and wonder — as we think about the larger context of visual culture around solar eclipses throughout history.</p>
<h2>Technical, safety challenges</h2>
<p>Photographing a solar eclipse presents some <a href="https://www.youtube.com/watch?v=dClhdu0oyWM">technical and safety challenges</a>. There are some preparations you can undertake, including ensuring your camera (<a href="https://www.cbc.ca/news/canada/total-solar-eclipse-phone-photos-2024-1.7149062">even smartphone cameras!</a>) has a solar filter. It is also important to be familiar with your camera, to practice using it in different light conditions before the eclipse. </p>
<p>The changes in light qualities will be quick and drastic, so familiarity with aperture and shutter speed will be important on the big day. A tripod will help reduce blurring when a longer exposure is required. If there are clouds, it’s still important to be cautious and wear protective glasses and the ability to capture an image will depend on the extent of cloud cover. The viewing experience will be different, but sky will still darken, creating changes in the colour and the way light passes through the clouds. </p>
<p>There are also some more creative ways to think about capturing the experience, including <a href="https://www.asc-csa.gc.ca/eng/youth-educators/activities/fun-experiments/eclipse-projector.asp">making a pinhole projector</a>. </p>
<p>This simple device can be made from a cardboard box and allows for both safe viewing and some interesting images.</p>
<h2>First photographs of eclipses</h2>
<p>But if your photographs don’t conform to your expectations, you are in good company. In 1842 Italian physicist <a href="https://hyperallergic.com/392269/the-first-photographs-of-a-solar-eclipse/">Gian Alessandro Majocchi attempted to photograph</a> the total solar eclipse that took place that July. Surviving records indicate he only had partial success: His resulting daguerreotype images — an early <a href="https://www.loc.gov/collections/daguerreotypes/articles-and-essays/the-daguerreotype-medium/#">photography technique invented by Louis-Jacques-Mandé Daguerre in 1839, involving treating a silver-coated copper plate with light sensitive chemicals</a> — are lost.</p>
<p>Majocchi was able to capture a few photographs <a href="https://babel.hathitrust.org/cgi/pt?id=hvd.fl1241&view=1up&seq=265">before and after</a> the <a href="https://www.cbc.ca/news/science/total-solar-eclipse-where-how-1.7129716">moments of totality</a>.</p>
<h2>Reminder of wonder, togetherness</h2>
<p>Apart from technical aspects, a successful photograph of the eclipse serves as a lasting reminder of the sense of wonder and the feeling of being part of something larger than ourselves. </p>
<p>This is the kind of event that brings people together, and the shared experience continues long after the eclipse ends through photographs that serve as memory markers and tangible proof that you were there to witness the eclipse. And even though many of us might end up with similar photographs, there is something significant about so many people taking pictures of the same event.</p>
<p>For example, <a href="https://psycnet.apa.org/record/2016-27715-001">taking photographs of events can increase a person’s enjoyment of the experience</a>, as the research of marketing professor Kristin Diehl and colleagues has examined. </p>
<p>Photography allows us to preserve memories, share them with others and relive those moments in the future. What makes an image stand out among the millions shared daily on social media often comes down to a combination of factors: its visual impact, the story it tells and the emotional resonance it can hold for others viewing it. In other words, much of what we share is about the broader experience.</p>
<h2>Proof of experience, connection across time</h2>
<p>Photographs also have long fulfilled a deep-seated need for proof of experience. We were there. Whether a blurry cell phone image of the <em>Mona Lisa</em> or a snapshot of the eclipse, these images serve as tangible reminders of our experiences. They validate our memories, anchor the stories we tell and allow us to share these moments with others. </p>
<p>Looking at images of people taking in <a href="https://www.atlasobscura.com/articles/century-eclipse-watching-photos">an eclipse during other eras can also offer a shared sense of connection across time</a>. This is a phenomenon that is bigger than us and these images connect us to the experiences of previous generations. </p>
<p>Scientific photographs of an eclipse, like the ones <a href="https://siarchives.si.edu/collections/siris_arc_308088">Thomas Smillie</a> made for the Smithsonian in 1900, may have been heralded as <a href="https://siarchives.si.edu/blog/smillie-and-1900-eclipse">technological breakthroughs</a>. Yet <a href="https://www.atlasobscura.com/articles/century-eclipse-watching-photos">there is something especially compelling about photographs of people gathered together, stopping for a moment and looking skyward</a>.</p>
<h2>Photographs yield partial insights</h2>
<p>A <a href="https://hyperallergic.com/392269/the-first-photographs-of-a-solar-eclipse/">daguerreotype of a solar eclipse taken on July 28, 1851 is the first known successful photograph of the solar corona</a>. This image was made at the Royal Prussian Observatory in Königsberg (contemporary Kaliningrad, Russia) by Johann Julius Friedrich Berkowski with the aid of a telescope. <a href="https://www.space.com/37656-first-total-solar-eclipse-photo-ever.html">The 84-second exposure allowed Berkowski to capture the moment in incredible detail</a>.</p>
<p>In 1890, the <em>American Journal of Photography</em> proclaimed <a href="https://babel.hathitrust.org/cgi/pt?id=hvd.fl1241&view=1up&seq=265">“probably in no department of science, certainly in no branch of astronomical science, has photography been of such use as in the study of solar eclipses</a>.” As the editors note, photography certainly can shape our understanding of the world, help to create new knowledge and provide valuable insights into the nature of the universe. </p>
<p>But there is also a limit to what photography can do. The experience of a solar eclipse goes beyond the visible: <a href="https://eclipse2017.nasa.gov/temperature-change-during-totality">temperatures drop</a>, <a href="https://www.audubon.org/news/total-solar-eclipse-coming-how-will-birds-and-other-wildlife-react">the behaviour of nonhuman animals can suddenly shift</a> and many report <a href="https://www.cbc.ca/player/play/1.7149511">unanticipated emotional or spiritual responses</a>.</p>
<h2>Many visual, artistic responses</h2>
<p>Further, there is a long history of <a href="https://doi.org/10.1038/508314a">eclipses being recorded in a range of different visual media</a>. For example, the <a href="https://doi.org/10.1017/S1743921314004621">Shang Dynasty in China provides a visual record of solar eclipses</a> via ancient script carved <a href="https://asia-archive.si.edu/learn/chinas-calligraphic-arts/oracle-bone-script">into oracle bones</a>.</p>
<p><a href="https://smarthistory.org/peter-paul-rubens-elevation-of-the-cross/">A 1610 painting by Peter Paul Rubens, called <em>The Elevation of the Cross</em></a>, illustrates the long and complex history of connections between phenomenon like eclipses and religious beliefs. In the early 20th century, American painter Howard Russell Butler produced a series of paintings in which he focused on <a href="https://hyperallergic.com/393623/howard-russell-butler-eclipse-paintings/">aspects of the eclipse that were difficult to capture with black and white photography — the changing quality of light and colours of the sky</a>. </p>
<p>The <a href="https://artmuseum.princeton.edu/transient-effects/eclipses-art/blackstar">video accompanying David Bowie’s <em>Black Star</em></a> (2016) opens with a total solar eclipse.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/kszLwBaC4Sw?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Video for David Bowie’s ‘Black Star.’</span></figcaption>
</figure>
<p>This is evocative visual imagery that complements the song’s themes of mortality — and offers a nod to long-held understandings of an eclipse as a symbol of impending doom. This symbolism was especially poignant as this was the title track of Bowie’s last studio album.</p>
<p>These types of artistic responses to celestial events foreground personal interpretation and emotional responses. They also foreground and reflect social, cultural, and spiritual meanings associated with a solar eclipse. </p>
<p>Could the act of sharing our eclipse photographs provide a point of fusion between providing evidence and these less tangible — but equally valid — moments of engagement?</p><img src="https://counter.theconversation.com/content/225241/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Keri Cronin has previously received funding from the Social Sciences and Humanities Research Council of Canada.</span></em></p><p class="fine-print"><em><span>Amy Friend does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Apart from technical aspects, a successful photograph of the eclipse serves as a lasting reminder of the sense of wonder and the feeling of being part of something larger than ourselves.Amy Friend, Associate professor, Visual Arts Department, Brock UniversityKeri Cronin, Professor, History of Art & Visual Culture, Brock UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2240412024-02-21T17:27:54Z2024-02-21T17:27:54ZThe brightest object ever observed in the night sky is a black hole that’s growing by the equivalent of one Sun a day<figure><img src="https://images.theconversation.com/files/576981/original/file-20240221-28-83koz3.jpg?ixlib=rb-1.1.0&rect=5%2C5%2C3828%2C2149&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/black-hole-slowly-rotating-space-event-2012670551">Merlin74 / Shutterstock</a></span></figcaption></figure><p><a href="https://www.nature.com/articles/s41550-024-02195-x">A new study</a> published in Nature Astronomy describes the most luminous object ever observed by astronomers. It is a black hole with a mass of 17 billion Suns, swallowing a greater amount of mass than the Sun every single day.</p>
<p>It has been known about for several decades, but since it is so bright, astronomers assumed it must be a nearby star. Only recent observations revealed its extreme distance and luminosity.</p>
<p>The object has been dubbed J0529-4351. This name simply refers to its coordinates on the celestial sphere – a way of projecting the objects in the sky onto the inside of a sphere. It is a type of <a href="https://esahubble.org/wordbank/quasar/">object called a quasar</a>.</p>
<p>The physical nature of quasars was initially unknown. But in 1963, the visible light from a <a href="https://www.wired.com/2008/08/dayintech-0805/">quasar called 3C 273</a> was split into all its wavelengths (known as its spectrum). This showed that it was located nearly 2 billion light years away. </p>
<p>Given how bright 3C 273 appears to us, and how far away it is, it must be extremely luminous – a term in astronomy that refers to the amount of light emitted by an object in a unit of time. The only known power source for such extreme luminosity was through material falling into a <a href="https://science.nasa.gov/universe/black-holes/">supermassive black hole</a>. Quasars are therefore the most actively growing black holes in the universe.</p>
<h2>Power source</h2>
<p>Supermassive black holes often sit at the centres of galaxies. As with all quasars, J0529-4351 is powered by material, mostly super-heated hydrogen and helium gas, falling into its black hole from the surrounding galaxy. </p>
<p>Roughly one times the Sun’s mass is falling into this black hole every day. Exactly how so much gas can be channelled into the centre of galaxies to increase the mass of black holes is an unanswered question in astrophysics.</p>
<p>At the galaxy’s centre, the gas forms into a thin disk shape. The properties of viscosity (resistance to the flow of matter in space) and friction in the thin disk help heat the gas to tens of thousands of degrees Celsius. This is hot enough to glow when viewed at ultraviolet and visible light wavelengths. It is that glow that we can observe from Earth. </p>
<p>At around 17 billion Suns in mass, J0529-4351 is not the most massive known black hole. One object, at the centre of the galaxy cluster Abell 1201, is <a href="https://www.space.com/largest-known-black-hole-discovered-through-gravitational-lensing">equivalent to 30 billion Suns</a>. However, we need to bear in mind that because of the time taken for light to travel across the vast distance between this object and Earth, we are witnessing it when the universe was only 1.5 billion years old. Its is now around 13.7 billion years old. </p>
<p>So this black hole must have been growing, or accreting, at this rate for a significant fraction of the age of the universe by the time it was observed. The authors believe the gas accretion by the black hole is happening close to the limit placed by the laws of physics. Faster accretion causes a more luminous disk of gas around the black hole which in turn can halt any more material falling in.</p>
<h2>Story of the discovery</h2>
<p>J0529-4351 has been known about for decades, but despite having an accretion disk of gas 15,000 times larger than our Solar System and occupying its own galaxy – which is probably close to the size of the Milky Way – it is so far away, it appears as a single point of light in our telescopes.</p>
<p>This means it is difficult to distinguish from the billions of stars in our own galaxy. To discover that it is in fact a distant, powerful, supermassive black hole required some more complex techniques. Firstly, astronomers collected light from the middle of the infrared waveband (light with much longer wavelengths than those we can see). </p>
<p>Stars and quasars look quite different to one another at those wavelengths. To confirm the observation, a spectrum was taken (much as it was with the quasar 3C 273), using the <a href="https://rsaa.anu.edu.au/observatories/telescopes/anu-23m-telescope">Australian National University’s 2.3 metre telescope</a> at Siding Spring Observatory, New South Wales. </p>
<p>And, as with 3C 273, the spectrum revealed both the nature of the object and how far away it was – 12 billion light years. This highlighted how extreme its luminosity must be.</p>
<h2>Detailed checks</h2>
<p>Despite these measurements, a number of checks needed to be made to confirm the true luminosity of the quasar. Firstly, astronomers needed to make sure that the light had not been magnified by a source in the sky that was closer to Earth. Much like lenses used in spectacles or binoculars, galaxies can act as lenses. They are so dense that they can bend and magnify the light of more distant sources that are perfectly aligned behind them. </p>
<p>Data from the European Space Agency’s Gaia satellite, which has extremely precise measurements of J0529-4351’s position, was used to determine that J0529-4351 is truly a single non-lensed source of light in the sky. This is backed up by more detailed spectra taken with the <a href="https://www.eso.org/public/unitedkingdom/teles-instr/paranal-observatory/vlt/">European Southern Observatory’s Very Large Telescope</a> (VLT) facility in Chile. </p>
<p>J0529-4351 is likely to become a very significant tool for the future study of quasars and black hole growth. The mass of black holes is a fundamental property but is very difficult to measure directly, as there is no standard set of weighing scales for such absurdly large, mysterious objects. </p>
<p>One technique is to measure the effect the black hole has on more diffuse gas orbiting it in large clouds, called the “broad line region”. This gas is revealed in the spectrum through wide “emission lines”, which are caused by electrons jumping between specific energy levels in the ionised gas. </p>
<p>The width of these lines is directly related to the mass of the black hole, but the calibration of this relationship is very poorly tested for the most luminous objects such as J0529-4351. However, because it is so physically large and so luminous, J0529-4351 will be observable by a new instrument being installed on the VLT, <a href="https://www.eso.org/public/unitedkingdom/teles-instr/paranal-observatory/vlt/vlt-instr/gravity+/">called Gravity+</a>. </p>
<p>This instrument will give a direct measurement of the black hole mass and calibrate the relationships used to estimate masses in other high-luminosity objects.</p><img src="https://counter.theconversation.com/content/224041/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Philip Wiseman works at the University of Southampton and is funded by the Science and Technology Facilities Council.</span></em></p>The extreme object could tell us more about the environment around black holes.Philip Wiseman, Research Fellow, Astronomy, University of SouthamptonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2156532024-02-11T13:50:28Z2024-02-11T13:50:28ZAn astronomer’s lament: Satellite megaconstellations are ruining space exploration<figure><img src="https://images.theconversation.com/files/574233/original/file-20240207-22-qbjsk9.jpg?ixlib=rb-1.1.0&rect=0%2C35%2C6000%2C3952&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Telescopes have to contend with light pollution from satellites.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>I used to love rocket launches when I was younger. During every launch, I imagined what it would feel like to be an astronaut sitting in the spacecraft, listening to that final countdown and then feeling multiple gees push me up through the atmosphere and away from our blue marble. </p>
<p>But as I learned more about the <a href="https://www.technologyreview.com/2018/06/22/142160/this-is-how-many-people-wed-have-to-send-to-proxima-centauri-to-make-sure-someone-actually/">severe limitations of human spaceflight</a>, I turned my attention to the oldest and most accessible form of space exploration: the science of astronomy.</p>
<p>Since 2019, I’ve watched my unencumbered enthusiasm for rocket launches soften to tepid interest, and finally sour to outright dread. <a href="https://globalnews.ca/news/9910084/the-new-space-race-2023/">The corporate space race</a>, led by SpaceX, is entirely responsible for this transformation in my mindset. </p>
<p>I am worried by the complete shift to the move-fast-and-break-things attitude that comes from the tech sector instead of government scientific agencies. I am put off by the <a href="https://press.uchicago.edu/ucp/books/book/chicago/A/bo184287883.html">colonialist language and billionaire-worship</a> of private corporations. I am increasingly furious at the <a href="https://www.startribune.com/string-lights-sky-not-ufo-starlink-satellite-internet/600324333/">nonexistent public education</a> and lack of transparency offered by these companies. </p>
<p>The final nail in the coffin for my love of rocket launches came with <a href="https://www.cnn.com/videos/business/2022/04/04/spacex-satellite-pollution-gothere-cnn-plus.cnn">SpaceX’s Starlink satellite megaconstellations</a>.</p>
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Read more:
<a href="https://theconversation.com/soon-1-out-of-every-15-points-of-light-in-the-sky-will-be-a-satellite-170427">Soon, 1 out of every 15 points of light in the sky will be a satellite</a>
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<h2>Crowded orbits</h2>
<p>The corporate space race is well underway, with private companies flooding Low Earth Orbit with <a href="https://planet4589.org/space/con/conlist.html">thousands of mass-produced satellites</a>. In previous decades, the prohibitively high cost of launch kept the rate of increase and total number of satellites from growing too rapidly. But launches have been getting steadily cheaper for years.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/OFfV33_eYPI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Al Jazeera reports on the impacts of Starlink satellites.</span></figcaption>
</figure>
<p>SpaceX has launched thousands of their own Starlink communication satellites, as well as hundreds of satellites for their direct competitors. <a href="https://www.illdefined.space/2023-global-space-activity-dashboards/">Half of all launches worldwide in 2023</a> were SpaceX rockets. </p>
<p>As an astronomer, I’m painfully aware of what these thousands of new satellites have done to the night sky worldwide. They reflect sunlight long after the sky has grown dark, looking like moving stars. </p>
<p>Starlink satellites are the most numerous and occupy some of the lowest orbits, so they make up the majority of the satellites seen in the sky. </p>
<p>Last year, SpaceX launched one of the <a href="https://doi.org/10.1038/s41586-023-06672-7">brightest objects in the sky</a> on behalf of another company: BlueWalker 3, a satellite with the same sky-footprint as a small house. They plan to operate a fleet of dozens, <a href="https://rdcu.be/drQOU">each as bright</a> as the brightest stars in the sky.</p>
<h2>Lost information and knowledge</h2>
<p>These satellites are now increasingly obstructing telescopic space exploration, <a href="https://www.nytimes.com/2024/01/09/science/astronomy-telescopes-satellites-spacex-starlink.html">both on the ground</a> and <a href="https://doi.org/10.1038/s41550-023-01903-3">in space</a>. Astronomers are the canaries in the coal mine for this rapidly expanding experiment in orbit: we see these satellites increasingly affecting our research every day.</p>
<p>I have watched over the past five years as satellite streaks in my own research images from the <a href="https://www.cfht.hawaii.edu/">Canada-France-Hawaii Telescope</a> have changed from an unusual occurrence to lost data in nearly every image.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/568276/original/file-20240108-25-vkyhs5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a series of grey boxes with white streaks" src="https://images.theconversation.com/files/568276/original/file-20240108-25-vkyhs5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/568276/original/file-20240108-25-vkyhs5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=491&fit=crop&dpr=1 600w, https://images.theconversation.com/files/568276/original/file-20240108-25-vkyhs5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=491&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/568276/original/file-20240108-25-vkyhs5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=491&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/568276/original/file-20240108-25-vkyhs5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=617&fit=crop&dpr=1 754w, https://images.theconversation.com/files/568276/original/file-20240108-25-vkyhs5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=617&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/568276/original/file-20240108-25-vkyhs5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=617&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A composite of 29 individual exposures from the Canada-France-Hawaii Telescope on Maunakea, taken in August 2022. The horizontal and diagonal white lines are bright satellites that unexpectedly flew through the field of view during observations, covering any objects behind them.</span>
<span class="attribution"><span class="source">(P. Cowan/W. Fraser/S. Lawler/CLASSY Survey Team/CFHT)</span></span>
</figcaption>
</figure>
<p>Astronomy is the only way to learn about the universe, the overwhelming majority of which can never be explored by humans. The farthest human-made object from Earth is the <a href="https://voyager.jpl.nasa.gov/mission/status/">Voyager 1 probe</a>, now eight times farther from the sun than Neptune after 46 years continuously travelling significantly faster than a speeding bullet. </p>
<p>But even if Voyager 1 was pointed directly toward our nearest neighbouring star, Proxima Centauri (it’s not), it would take over 100,000 years to get there. We are light-years away from having technology that can robotically explore even our neighbouring solar systems on a human timescale, let alone bring humans out to the stars.</p>
<p>The vast majority of astronomy research is carried out by telescopes on Earth: large optical telescopes on remote mountaintops, large radio telescopes in radio-quiet zones that are meticulously maintained, as well as smaller telescopes scattered around the world.</p>
<p>There are a handful of telescopes in Low Earth Orbit that also have to <a href="https://skyandtelescope.org/astronomy-news/satellite-trails-mar-hubble-images/">contend with light pollution</a> from Starlink and other megaconstellations. There are also a <a href="https://webb.nasa.gov/content/about/orbit.html">handful of telescopes outside Earth orbit</a> which can only operate for a few years, unlike ground-based facilities that can be maintained and enhanced with new technologies for decades.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/574239/original/file-20240207-28-qmjb00.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a large white dome looms against a dark sky" src="https://images.theconversation.com/files/574239/original/file-20240207-28-qmjb00.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/574239/original/file-20240207-28-qmjb00.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/574239/original/file-20240207-28-qmjb00.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/574239/original/file-20240207-28-qmjb00.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/574239/original/file-20240207-28-qmjb00.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/574239/original/file-20240207-28-qmjb00.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/574239/original/file-20240207-28-qmjb00.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Canada-Hawaii-France telescope, located on the summit of Mauna Kea, a dormant volcano located on the island of Hawaii.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<h2>Government regulation needed</h2>
<p>Space exploration using Earth-based telescopes is growing increasingly less effective as more bright and radio-loud satellites are placed between Earth and the stars. But there are much worse problems ahead if corporations continue launching satellites: atmospheric pollution on launch and <a href="https://doi.org/10.1073/pnas.2313374120">reentry</a>, ground casualty risks from <a href="https://doi.org/10.1038/s41550-022-01718-8">reentries</a>, and the very real possibility of a <a href="https://doi.org/10.1038/s41598-021-89909-7">runaway collisional cascade in orbit</a>, referred to as the Kessler Syndrome.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-rapidly-growing-rocket-industry-could-undo-decades-of-work-to-save-the-ozone-layer-unless-we-act-now-198982">A rapidly growing rocket industry could undo decades of work to save the ozone layer – unless we act now</a>
</strong>
</em>
</p>
<hr>
<p>Satellites are an incredibly useful part of our lives, but there are limits to how many can safely orbit Earth. Current regulations on launches and orbital operations by governments are very weak, and are not set up for the current regime of thousands of new satellites per year. </p>
<p>Regulation on the number of satellites in orbit would force corporations toward technology improvements and service models that use fewer satellites, keeping orbit usable for future generations.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/its-not-too-late-to-save-the-night-sky-but-governments-need-to-get-serious-about-protecting-it-158394">It's not too late to save the night sky, but governments need to get serious about protecting it</a>
</strong>
</em>
</p>
<hr>
<p>Ask your government representatives to support <a href="https://www.asc-csa.gc.ca/eng/transparency/consultations/what-we-heard-consulting-canadians-modern-regulatory-framework-space.asp">satellite regulation</a>, and expansion of <a href="https://crtc.gc.ca/eng/internet/internet.htm">rural broadband</a>. Get out and enjoy your <a href="https://www.cleardarksky.com/maps/lp/large_light_pollution_map.html">dark skies</a>, before they change. </p>
<p>With proper regulation, our oldest form of space exploration can continue. I desperately hope we never reach a point where the natural patterns in the sky are drowned out by anthropogenic ones, but without regulation, corporations will get us there soon.</p><img src="https://counter.theconversation.com/content/215653/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Samantha Lawler receives research funding from the Natural Sciences and Engineering Research Council of Canada.</span></em></p>Megaconstellations of satellites are hindering the most powerful tool for space exploration: telescopes.Samantha Lawler, Associate professor, Astronomy, University of ReginaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2186042023-12-31T20:27:24Z2023-12-31T20:27:24ZWant to buy a home telescope? Tips from a professional astronomer to help you choose<figure><img src="https://images.theconversation.com/files/565384/original/file-20231213-29-dpf9ef.jpg?ixlib=rb-1.1.0&rect=671%2C363%2C4722%2C3226&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.pexels.com/photo/silhouette-of-person-standing-on-a-field-under-starry-night-8495473/">Thirdman/Pexels</a></span></figcaption></figure><p>While the unaided eye or binoculars can reveal much of the night sky, a telescope reveals so much more. Seeing Saturn’s rings or the Moon’s craters with your own eyes can be an “oh wow” moment.</p>
<p>However, choosing the right telescope can be tricky. There are telescopes with lenses and telescopes with mirrors. Telescopes that are moved by hand and others that are electronically controlled. Telescopes also come in a range of sizes, with a trade-off between light-gathering power, portability and price.</p>
<p>While there’s much to consider, changes in pricing and technology mean spectacular views of the universe are more accessible than just a decade ago.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/want-to-get-into-stargazing-a-professional-astronomer-explains-where-to-start-218921">Want to get into stargazing? A professional astronomer explains where to start</a>
</strong>
</em>
</p>
<hr>
<h2>How big should the aperture be?</h2>
<p>Aperture is fundamental for telescopes. The bigger the light-collecting lens or mirror, the fainter the objects you can see. Double the aperture from 50mm diameter to 100mm diameter, and the light-collecting area quadruples. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/562252/original/file-20231128-15-sp0qw3.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A circular mirror in a museum behind a glass screen" src="https://images.theconversation.com/files/562252/original/file-20231128-15-sp0qw3.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/562252/original/file-20231128-15-sp0qw3.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/562252/original/file-20231128-15-sp0qw3.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/562252/original/file-20231128-15-sp0qw3.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/562252/original/file-20231128-15-sp0qw3.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/562252/original/file-20231128-15-sp0qw3.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/562252/original/file-20231128-15-sp0qw3.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A bigger mirror or lens captures more light. This mirror is from one of William Herschel’s telescopes.</span>
<span class="attribution"><span class="source">Michael Brown</span></span>
</figcaption>
</figure>
<p>The aperture also limits the level of detail you can see, <a href="https://theconversation.com/explainer-what-is-wave-particle-duality-7414">due to the diffraction</a> (interference) of light.</p>
<p>Again, bigger is better – a larger aperture telescope will produce sharper images than a smaller aperture telescope of comparable design. Earth’s turbulent atmosphere also blurs images, which can limit the detail seen when the aperture is more than 150mm.</p>
<p>Sometimes cheaper telescopes are advertised by magnification, but a small telescope with extreme magnification just makes blurry images bigger without revealing more detail. </p>
<h2>Refractor or reflector?</h2>
<p>Should you buy a telescope with a refracting lens or a reflecting mirror? It depends what you want to look at, and your budget.</p>
<p><strong>Refracting telescopes</strong></p>
<p><a href="https://en.wikipedia.org/wiki/Refracting_telescope">Refracting telescopes</a> can be good for viewing objects on Earth and in the sky. Refracting telescopes with short focal lengths (where light is brought to a focus near the lens) can be quite compact and good for low magnification views, which is great for sweeping across dark country skies.</p>
<p>However, there are catches. While 70mm aperture refracting telescopes can be quite affordable, bigger refractor telescopes are often more expensive than comparable reflecting telescopes.</p>
<p>Refracting telescopes also suffer from chromatic aberration – where different colours aren’t brought to a common focus – and this is particularly noticeable at high magnification when stars get coloured halos. This can be mitigated using complex lens designs, but that adds to the cost.</p>
<p><strong>Reflecting telescopes</strong></p>
<p><a href="https://en.wikipedia.org/wiki/Reflecting_telescope">Reflecting telescopes</a> use mirrors to focus light. These tend to be larger and don’t suffer from chromatic aberration.</p>
<p><a href="https://www.space.com/what-are-dobsonian-telescopes">Dobsonian telescopes</a> have a simple Newtonian optical design and wooden mounts, and are a very cost effective (if sometimes bulky) option for larger apertures. <a href="https://en.wikipedia.org/wiki/Schmidt%E2%80%93Cassegrain_telescope">Schmidt-Cassegrain</a> and Maksutov telescopes, which use a combination of lenses and mirrors, are more compact (a big plus), but also more complex and expensive.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/562041/original/file-20231128-15-u4sl89.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A white telescope on a black sand sitting on a tiled porch" src="https://images.theconversation.com/files/562041/original/file-20231128-15-u4sl89.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/562041/original/file-20231128-15-u4sl89.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/562041/original/file-20231128-15-u4sl89.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/562041/original/file-20231128-15-u4sl89.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/562041/original/file-20231128-15-u4sl89.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/562041/original/file-20231128-15-u4sl89.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/562041/original/file-20231128-15-u4sl89.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Dobsonian telescopes are an affordable option for a large aperture telescope.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/31667440@N04/45423626755">Wutthichai Charoenburi/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>How do I find things in the sky? Depends on the mount</h2>
<p>Want to look at a celestial object? You will need to point your telescope in the right direction, keep it steady, and follow the object as it moves across the sky (due to Earth’s rotation).</p>
<p>To do this, a telescope <a href="https://www.skyatnightmagazine.com/advice/a-basic-guide-to-telescope-mounts">needs a mount</a>, which is often sold with the telescope but can also be bought separately. Mounts fall into two broad categories. </p>
<p><strong>Equatorial mounts</strong> have an axis aligned with Earth’s axis, so a single motor can compensate for Earth’s rotation. These mounts were essential for taking long exposure images with telescopes prior to computers and tend to be relatively heavy.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/562061/original/file-20231128-29-ygzgy4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A large black telescope on a white mount sitting in a verandah" src="https://images.theconversation.com/files/562061/original/file-20231128-29-ygzgy4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/562061/original/file-20231128-29-ygzgy4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/562061/original/file-20231128-29-ygzgy4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/562061/original/file-20231128-29-ygzgy4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/562061/original/file-20231128-29-ygzgy4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/562061/original/file-20231128-29-ygzgy4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/562061/original/file-20231128-29-ygzgy4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Telescopes need mounts so they can be positioned and securely held in place.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/astro_mike/4151500835/">Mike White/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p><strong>Alt-azimuth mounts</strong> have a vertical and a horizontal axis (how a camera is mounted on a tripod, for example), and tend to be cheaper and lighter than equatorial mounts. With the advent of cheap computing, they can now be used to automatically point at and track celestial objects.</p>
<p>To point a telescope at celestial objects you can move it manually or have electronics assist you, including “goto” mounts with motors that shift the telescope for you. </p>
<p>A completely manual telescope will be cheaper than a telescope with automation, but you will need to navigate the sky yourself.</p>
<p>Electronic assistance for navigating the sky is rapidly evolving and getting cheaper. Many telescopes on the market now use GPS and a smartphone app, which simplifies the process and makes everything more portable.</p>
<h2>Do I need a finder scope?</h2>
<p>Regardless of how you point your telescope, having a 30–50mm aperture auxiliary “finder” scope can be useful for small telescopes and essential for larger telescopes. </p>
<p>Large telescopes typically view a tiny patch of the sky, which makes finding your way tricky. A finder scope with a wider view and crosshairs simplifies things. Even telescopes with goto electronics often need to be calibrated with bright stars and locating them is easier with a finder scope.</p>
<h2>What about the eyepiece?</h2>
<p>An essential part of most telescopes is the <a href="https://www.skyatnightmagazine.com/advice/skills/eyepieces-the-basics">eyepiece</a> you look through. Sometimes decent telescopes are sold with quite cheap eyepieces, but it can be relatively inexpensive to upgrade to a better one.</p>
<p>A good start is a low-magnification eyepiece for sweeping views, and a high-magnification eyepiece for planets.</p>
<p><a href="https://www.skyatnightmagazine.com/advice/what-is-a-plossl-eyepiece">Plössl eyepieces</a> are affordable and provide good views. More complex eyepieces that provide better views are also available, and far cheaper than they once were.</p>
<p>If you want to look at the Sun, you <em>must</em> get a specially designed <a href="https://www.skyatnightmagazine.com/advice/telescope-filters-beginners-guide">solar filter</a>. Never point a telescope (including the finder scope) at the Sun without filters – it can permanently damage eyes and shatter lenses.</p>
<h2>What if I want to take astro photos?</h2>
<p>Taking basic astronomical photos has become much easier with smartphones. While you can hold a phone to the telescope eyepiece for a photo of the Moon or a planet, you will get better results with an adapter that holds your phone securely in place. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/562040/original/file-20231128-29-p4frq7.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A zoomed in view of the Moon with one side cast in a red shadow" src="https://images.theconversation.com/files/562040/original/file-20231128-29-p4frq7.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/562040/original/file-20231128-29-p4frq7.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=577&fit=crop&dpr=1 600w, https://images.theconversation.com/files/562040/original/file-20231128-29-p4frq7.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=577&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/562040/original/file-20231128-29-p4frq7.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=577&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/562040/original/file-20231128-29-p4frq7.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=724&fit=crop&dpr=1 754w, https://images.theconversation.com/files/562040/original/file-20231128-29-p4frq7.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=724&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/562040/original/file-20231128-29-p4frq7.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=724&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A photo of a lunar eclipse taken with a small telescope and iPhone.</span>
<span class="attribution"><span class="source">Michael Brown</span></span>
</figcaption>
</figure>
<p>Of course, better images can be taken with astronomy-specific cameras that can take very short exposures (for planets) or very long exposures (for fainter nebulae and galaxies). For long exposures, automatic tracking of celestial objects is essential, and that adds to a telescope’s price.</p>
<p><a href="https://www.digitalcameraworld.com/buying-guides/best-smart-telescope">Smart telescopes</a> are a relatively recent addition to the market. These goto telescopes have no eyepieces and only capture images electronically. As modern detectors are more sensitive than our eyes, they can capture quite spectacular images with a relatively small portable telescope, even when there’s light pollution.</p>
<p>However, you do lose the experience of seeing the universe directly with your own eyes through the eyepiece.</p>
<h2>Try before you buy!</h2>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/562250/original/file-20231128-17-r36dan.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A small telescope sitting on a simple mount on a concrete floor" src="https://images.theconversation.com/files/562250/original/file-20231128-17-r36dan.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/562250/original/file-20231128-17-r36dan.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/562250/original/file-20231128-17-r36dan.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/562250/original/file-20231128-17-r36dan.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/562250/original/file-20231128-17-r36dan.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/562250/original/file-20231128-17-r36dan.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/562250/original/file-20231128-17-r36dan.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A second-hand bargain, like this 70mm refractor telescope, may be lurking in someone’s garage.</span>
<span class="attribution"><span class="source">Michael Brown</span></span>
</figcaption>
</figure>
<p>If there’s a local amateur astronomical society, you can sign up or attend a star party. There should be plenty of telescopes, and owners happy to wax lyrical about them.</p>
<p>A specialist shop can also give a direct experience of a telescope: its size and how it works (with limitations during daytime). For example, you may find a telescope is too bulky or technical for your needs.</p>
<p>Online shopping can save money, but may have less customer support than a local shop. You could also snap up a bargain buying second hand, and a seller may allow you to test their telescope on the Moon and planets before buying.</p>
<p>There’s a lot to take on board before buying a telescope. Aperture, size, cost and other factors need to be considered. But there are many good options out there, and with a good choice you can see some wondrous things. And perhaps have an “oh wow” moment.</p><img src="https://counter.theconversation.com/content/218604/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael J. I. Brown receives research funding from the Australian Research Council and Monash University.
</span></em></p>A telescope can reveal so much of the night sky, including Saturn’s rings and the Moon’s craters. But choosing the right telescope is a difficult decision – here’s what you need to know.Michael J. I. Brown, Associate Professor in Astronomy, Monash UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2170122023-11-08T16:41:22Z2023-11-08T16:41:22ZHow we’re building the world’s biggest optical telescope to crack some of the greatest puzzles in science<figure><img src="https://images.theconversation.com/files/557968/original/file-20231107-25-fl42fz.jpg?ixlib=rb-1.1.0&rect=237%2C89%2C5185%2C3533&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">ESO’s Extremely Large Telescope.</span> <span class="attribution"><span class="source">ESO/wikipedia</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Astronomers get to ask some of the most fundamental questions there are, ranging from whether we’re alone in the cosmos to what the nature of the mysterious dark energy and dark matter making up most of the universe is.</p>
<p>Now a large group of astronomers from all over the world is building the biggest optical telescope ever – the <a href="https://elt.eso.org/">Extremely Large Telescope (ELT)</a> — in Chile. Once construction is completed in 2028, it could provide answers that transform our knowledge of the universe. </p>
<hr>
<iframe id="noa-web-audio-player" style="border: none" src="https://embed-player.newsoveraudio.com/v4?key=x84olp&id=https://theconversation.com/how-were-building-the-worlds-biggest-optical-telescope-to-crack-some-of-the-greatest-puzzles-in-science-217012&bgColor=F5F5F5&color=D8352A&playColor=D8352A" width="100%" height="110px"></iframe>
<p><em>You can listen to more articles from The Conversation <a href="https://theconversation.com/us/topics/audio-narrated-99682">narrated by Noa</a>.</em></p>
<hr>
<p>With its 39-metre diameter primary mirror, the ELT will contain the largest, most perfect reflecting surface ever made. Its light-collecting power will exceed that of all other large telescopes combined, enabling it to detect objects millions of times fainter than <a href="https://supernova.eso.org/exhibition/0805/">the human eye can see</a>.</p>
<p>There are several reasons why we need such a telescope. Its incredible sensitivity will let it image some of the first galaxies ever formed, with light that has travelled for 13 billion years to reach the telescope. Observations of such distant objects may allow us to refine our understanding of cosmology and the nature of <a href="https://theconversation.com/dark-matter-should-we-be-so-sure-it-exists-heres-how-philosophy-can-help-184109">dark matter</a> and <a href="https://theconversation.com/the-experiments-trying-to-crack-physics-biggest-question-what-is-dark-energy-52917">dark energy</a>.</p>
<h2>Alien life</h2>
<p>The ELT may also offer an answer to the most fundamental question of all: are we alone in the universe? The ELT is expected to be the first telescope to track down Earth-like exoplanets — planets that orbit other stars but have a similar mass, orbit and proximity to their host as Earth. </p>
<p>Occupying the so-called Goldilocks zone, these Earth-like planets will orbit their star at just the right distance for water to neither boil nor freeze – providing the conditions for life to exist.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/557768/original/file-20231106-15-g3l1kl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Size comparison between the ELT and other telescope domes." src="https://images.theconversation.com/files/557768/original/file-20231106-15-g3l1kl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/557768/original/file-20231106-15-g3l1kl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=113&fit=crop&dpr=1 600w, https://images.theconversation.com/files/557768/original/file-20231106-15-g3l1kl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=113&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/557768/original/file-20231106-15-g3l1kl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=113&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/557768/original/file-20231106-15-g3l1kl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=142&fit=crop&dpr=1 754w, https://images.theconversation.com/files/557768/original/file-20231106-15-g3l1kl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=142&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/557768/original/file-20231106-15-g3l1kl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=142&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Size comparison between the ELT and other telescope domes.</span>
<span class="attribution"><span class="source">ESO/wikipeida</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>The ELT’s camera will have six times better resolution than that of the <a href="https://webb.nasa.gov/">James Webb Space Telescope</a>, allowing it to take the clearest images yet of exoplanets. But fascinating as these pictures will be, they will not tell the whole story.</p>
<p>To learn if life is likely to exist on an exoplanet, astronomers must complement imaging with spectroscopy. While images reveal shape, size and structure, spectra tell us about the speed, temperature and even the chemistry of astronomical objects.</p>
<p>The ELT will contain not one, but four spectrographs — instruments that disperse light into its constituent colours, much like the iconic prism on the Pink Floyd’s The <a href="https://theconversation.com/the-dark-side-of-the-moon-at-50-an-album-artwork-expert-on-pink-floyds-music-marketing-revolution-200932">Dark Side of the Moon</a> album cover.</p>
<p>Each about the size of a minibus, and carefully environmentally controlled for stability, these spectrographs underpin all of the ELT’s key science cases. For giant exoplanets, the <a href="https://elt.eso.org/instrument/HARMONI/">Harmoni instrument</a> will analyse light that has travelled through their atmospheres, looking for the signs of water, oxygen, methane, carbon dioxide and other gases that indicate the existence of life.</p>
<p>To detect much smaller Earth-like exoplanets, the more specialised <a href="https://elt.eso.org/instrument/ANDES/">Andes instrument</a> will be needed. With a cost of around €35 million (£30 million), Andes will be able to detect tiny changes in the wavelength of light.</p>
<p>From previous satellite missions, astronomers already have a good idea of where to look in the sky for exoplanets. Indeed, there have been several thousand confirmed or “candidate” exoplanets detected using <a href="https://theconversation.com/explainer-how-do-you-find-exoplanets-24153">the “transit method”</a>. Here, a space telescope stares at a patch of sky containing thousands of stars and looks for tiny, periodic dips in their intensities, caused when an orbiting planet passes in front of its star.</p>
<p>But Andes will use a different method to hunt for other Earths. As an exoplanet orbits its host star, <a href="https://www.eso.org/public/unitedkingdom/videos/eso1035g/">its gravity tugs on the star, making it wobble</a>. This movement is incredibly small; Earth’s orbit causes the Sun to oscillate at just 10 centimetres per second — the walking speed of a tortoise. </p>
<p>Just as the pitch of an ambulance siren rises and falls as it travels towards and away from us, the wavelength of light observed from a wobbling star increases and decreases as the planet traces out its orbit.</p>
<figure class="align-center ">
<img alt="Artist's impression of ELT." src="https://images.theconversation.com/files/557969/original/file-20231107-19-l8m44m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/557969/original/file-20231107-19-l8m44m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=426&fit=crop&dpr=1 600w, https://images.theconversation.com/files/557969/original/file-20231107-19-l8m44m.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=426&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/557969/original/file-20231107-19-l8m44m.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=426&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/557969/original/file-20231107-19-l8m44m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=535&fit=crop&dpr=1 754w, https://images.theconversation.com/files/557969/original/file-20231107-19-l8m44m.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=535&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/557969/original/file-20231107-19-l8m44m.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=535&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Artist’s impression of ELT.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Extremely_Large_Telescope#/media/File:ELT_concept.jpg">ESO/L. Calçada/wikipedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Remarkably, Andes will be able to detect this minuscule change in the light’s colour. Starlight, while essentially continuous (“white”) from the ultraviolet to the infrared, contains bands where atoms in the outer region of the star absorb specific wavelengths as the light escapes, appearing dark in the spectra. </p>
<p>Tiny shifts in the positions of these features — around 1/10,000th of a pixel on the Andes sensor — may, over months and years, reveal the periodic wobbles. This could ultimately help us to find an Earth 2.0.</p>
<p>At Heriot-Watt University, we are piloting <a href="https://www.hw.ac.uk/news/articles/2023/planet-hunting-systems-for-the-extremely.htm">the development of a laser system</a> known as a frequency comb, that will enable Andes to reach such exquisite precision. Like the millimetre ticks on a ruler, the laser will calibrate the Andes spectrograph by providing a spectrum of light structured as thousands of regularly spaced wavelengths.</p>
<p>This scale will remain constant over decades, mitigating the measurement errors that occur from environmental changes in temperature and pressure.</p>
<p>With the ELT’s construction cost coming in at €1.45 billion, some will question the value of the project. But astronomy has a significance that spans millennia and transcends cultures and national borders. It is only by looking far outside our Solar System that we can gain a perspective beyond the here and now.</p><img src="https://counter.theconversation.com/content/217012/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Derryck Reid receives funding from the UK Science and Technology Facilities Council (STFC).</span></em></p>From improving our understanding of dark matter to revealing the location of Earth 2.0, the Extremely Large Telescope promises answers to some of the biggest scientific questions of our time.Derryck Telford Reid, Professor of Physics, Heriot-Watt UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2154662023-10-11T15:14:41Z2023-10-11T15:14:41ZThe afterglow of an explosive collision between giant planets may have been detected in a far-off star system<figure><img src="https://images.theconversation.com/files/553243/original/file-20231011-25-y5wvfs.jpeg?ixlib=rb-1.1.0&rect=2%2C0%2C1914%2C1431&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A visualisation of the huge, glowing planetary body produced by a planetary collision.</span> <span class="attribution"><a class="source" href="https://www.eurekalert.org/multimedia/1001427">Mark Garlick</a>, <span class="license">Author provided</span></span></figcaption></figure><p>The afterglow of a massive collision between two giant planets may have been detected for the first time. The wreckage of the collision could eventually cool and form an entirely new planet. If the observation is confirmed, it provides an amazing opportunity to watch the birth of a new world in real time and open a window into how planets form.</p>
<p>In December 2021, astronomers watching an otherwise unremarkable sun-like star <a href="https://astronomerstelegram.org/?read=14879">saw it begin to flicker</a>. For a few months, the visible light (the light we can see with our eyes) from this star continued to change. At times it would almost disappear, before returning to its previous brightness. </p>
<p>The star, which sits roughly 1,800 light years from Earth, was given the identifier ASASSN-21qj, after the <a href="https://www.astronomy.ohio-state.edu/asassn/">ASASN-SN astronomy survey</a> that first observed the star’s dimming. </p>
<p>Seeing stars dim like this is not uncommon. It’s generally attributed to material passing between the star and Earth. ASASSN-21qj may just have been added to a growing list of similar observations had it not been for an amateur astronomer, <a href="https://science.nasa.gov/people/arttu-sainio/">Arttu Sainio</a>. Sainio pointed out on social media that some two and a half years before the star’s light was seen to fade, the emission of infrared light coming from its location rose by roughly 4%. </p>
<p>Infrared light is most strongly emitted by objects at relatively high temperatures of a few hundred degrees Celsius. This posed the questions: were these two observations related and, if so, what the heck was going on around ASASSN-21qj?</p>
<h2>Planetary cataclysm</h2>
<p>Publishing our findings <a href="https://www.nature.com/articles/s41586-023-06573-9">in Nature</a>, we propose that both sets of observations could be explained by a cataclysmic collision between two planets. Giant impacts, as such collisions are known, are thought to be common in the final stages of the formation of planets. They dictate the final sizes, compositions, and thermal states of planets and mould the orbits of objects in those planetary systems. </p>
<p>In our solar system, giant impacts are thought to be responsible for the <a href="https://science.nasa.gov/uranus/facts/">odd tilt of Uranus</a>, the <a href="https://science.nasa.gov/mercury/facts/">high density of Mercury</a> and the <a href="https://news.uchicago.edu/explainer/formation-earth-and-moon-explained#moonform">existence of Earth’s Moon</a>. However, until now, we had little direct evidence of giant impacts ongoing in the galaxy. </p>
<figure class="align-center ">
<img alt="Artist's impression of the WISE telescope." src="https://images.theconversation.com/files/553260/original/file-20231011-19-jdcjpm.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/553260/original/file-20231011-19-jdcjpm.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/553260/original/file-20231011-19-jdcjpm.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/553260/original/file-20231011-19-jdcjpm.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/553260/original/file-20231011-19-jdcjpm.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/553260/original/file-20231011-19-jdcjpm.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/553260/original/file-20231011-19-jdcjpm.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Nasa’s WISE telescope observed an increase in the infrared light coming from the star.</span>
<span class="attribution"><a class="source" href="https://photojournal.jpl.nasa.gov/catalog/PIA17254">NASA/JPL-Caltech</a></span>
</figcaption>
</figure>
<p>In order to explain the observations, a collision would have needed to release more energy in the first few hours after impact than would be emitted from the star. Material from the colliding bodies would have been superheated and melted, vaporised or both.</p>
<p>The impact would have formed a hot, glowing mass of material hundreds of times larger than the original planets. The infrared brightening of ASASSN-21qj was observed by <a href="https://www.jpl.nasa.gov/missions/wide-field-infrared-survey-explorer-wise">Nasa’s WISE space telescope</a>. WISE only looks at the star every 300 days or so, and probably missed the initial flash of light from the impact. </p>
<p>However, the expanded planetary body produced by the impact will take a long time, perhaps millions of years, to cool and shrink to something we might recognise as a new planet. Initially, when this “post-impact body” was at its greatest extent, the light emitted from it could still be as high as several percent of emission from the star. Such a body could have produced the infrared brightening that we saw.</p>
<p>The impact would also have ejected great plumes of debris into a range of different orbits around the star. A fraction of this debris would have been vaporised by the shock of the impact, later condensing to form clouds of tiny ice and rock crystals. Over time, some of this clumpy cloud of material passed between ASASSN-21qj and Earth, blocking out a fraction of the visible light from the star and producing the erratic dimming. </p>
<figure class="align-center ">
<img alt="Neptune." src="https://images.theconversation.com/files/553274/original/file-20231011-25-9485zg.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/553274/original/file-20231011-25-9485zg.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=599&fit=crop&dpr=1 600w, https://images.theconversation.com/files/553274/original/file-20231011-25-9485zg.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=599&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/553274/original/file-20231011-25-9485zg.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=599&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/553274/original/file-20231011-25-9485zg.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=753&fit=crop&dpr=1 754w, https://images.theconversation.com/files/553274/original/file-20231011-25-9485zg.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=753&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/553274/original/file-20231011-25-9485zg.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=753&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The planets may have been similar to Neptune in the solar system.</span>
<span class="attribution"><a class="source" href="https://photojournal.jpl.nasa.gov/catalog/PIA01492">NASA/JPL</a></span>
</figcaption>
</figure>
<p>If our interpretation of the events is correct, studying this star system could help us understand a key mechanism of planet formation. Even from the limited set of observations we have so far, we have learned some very interesting things. </p>
<p>Firstly, to emit the amount of energy observed, the post-impact body must have been many hundreds of times the size of Earth. To create a body that large, the planets that collided must each have been several times the mass of Earth – possibly as large as the <a href="https://www.lpi.usra.edu/opag/outer_planets.pdf">“ice giant”</a> planets Uranus and Neptune. </p>
<p>Secondly, we estimate the temperature of the post-impact body to be around 700°C. For the temperature to be that low, the colliding bodies could not have been entirely made of rock and metal. </p>
<h2>Ice giants</h2>
<p>The outer regions of at least one of the planets must have contained elements with low boiling temperatures, such as in water. We therefore think that we have seen a collision between two Neptune-like worlds that are rich in ice. </p>
<p>The delay that was seen between the emission of infrared light and the observation of debris crossing the star suggests that the collision took place quite far away from the star – further away than the Earth is from the Sun. Such a system, in which there are ice giants far from the star, is more similar to our solar system than to many of the tightly-packed planetary systems astronomers often observe around other stars.</p>
<p>The most exciting aspect of this is that we can continue to watch the system evolve for many decades and test our conclusions. Future observations, using telescopes such as <a href="https://webbtelescope.org/home">Nasa’s JWST</a>, will determine the sizes and compositions of particles in the debris cloud, identify the chemistry of the upper layers of the post-impact body and track how this hot mass of debris cools down. We may even see new moons emerge. </p>
<p>These observations can inform our theories, helping us understand how giant impacts shape planetary systems. So far the only examples we’ve had are the echoes of impacts in our own solar system. We will now be able to watch the birth of a new planet in real time.</p><img src="https://counter.theconversation.com/content/215466/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Simon Lock receives funding from the UK Natural Environment Research Council (grant NE/V014129/1).</span></em></p><p class="fine-print"><em><span>Zoe Leinhardt receives funding from UK Science and Technology Facilities Council (grant number ST/V000454/1). </span></em></p><p class="fine-print"><em><span>Matthew Kenworthy does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The discovery provides a way to study the birth of an entirely new planet in real time.Simon Lock, NERC Research Fellow, School of Earth Sciences, University of BristolMatthew Kenworthy, Associate professor in Astronomy, Leiden UniversityZoe Leinhardt, Associate Professor, School of Physics, University of BristolLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2013412023-09-21T21:56:09Z2023-09-21T21:56:09ZCanada’s participation in the world’s largest radio telescope means new opportunities in research and innovation<figure><img src="https://images.theconversation.com/files/548371/original/file-20230914-8809-zchqj4.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2000%2C1000&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">An artist's impression of the Square Kilometre Array Observatory, the largest of its kind in the world.</span> <span class="attribution"><a class="source" href="https://skao.canto.global/v/SKAOLibrary/album/G20QH?viewIndex=1&column=image&id=m02qd2lp390bd092m1d4a9734g">(SKAO)</a></span></figcaption></figure><iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/canadas-participation-in-the-worlds-largest-radio-telescope-means-new-opportunities-in-research-and-innovation" width="100%" height="400"></iframe>
<p>Canada is about to <a href="https://www.canada.ca/en/national-research-council/news/2023/01/canada-announces-intention-to-become-full-member-of-international-skao-radio-astronomy-project.html">become a member</a> of the <a href="https://www.skao.int/en">Square Kilometre Array Observatory (SKAO)</a> — the world’s next giant radio telescope. This is a win for all Canadians, not just astronomers. </p>
<p>SKAO is a radio telescope made up of thousands of individual elements over vast areas. Its two remote sites are located, in partnership with <a href="https://www.skao.int/en/partners/429/local-and-indigenous-communities">local and Indigenous communities</a>, in the <a href="https://www.britannica.com/place/Karoo">Karoo desert region of South Africa</a> and the traditional lands of the <a href="https://research.csiro.au/ska/location/">Wajarri Yamaji in outback Western Australia</a>. </p>
<p>An international partnership that will operate the observatory includes 16 countries located on five continents.</p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/Cl895XftKK6","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<h2>Radio observations</h2>
<p>Observing the sky with radio telescopes is not just (or even mostly) about looking for aliens. Electromagnetic radiation at radio wavelengths is produced by some of the most interesting and mysterious objects in the universe. These range from the supermassive black holes at the hearts of distant galaxies to pulsars that spin at dizzying rates like the fastest lighthouses, to the baffling explosions that produce <a href="https://www.dunlap.utoronto.ca/observational-research/time-domain-science/fast-radio-bursts/">fast radio bursts</a>. </p>
<p>To detect these faint signals when they reach Earth, we need many sophisticated antennas spread over large geographical areas, and located in places far from human-generated interference. </p>
<h2>Canadian involvement</h2>
<p>Canadian scientists are involved in many international projects, including the <a href="https://home.cern/science/accelerators/large-hadron-collider">Large Hadron Collider in Geneva, Switzerland</a> and <a href="https://www.snolab.ca/">SNOLAB underground laboratory in Lively, Ont.</a>. </p>
<p>The Canadian Astronomical Society makes recommendations on telescope participation through a <a href="https://casca.ca/?page_id=11499">decade long range plan</a> in which the professional astronomy community considers its priorities. Full participation in the SKA was the highest priority among large projects of the most recent plan <a href="https://casca.ca/?page_id=11499">that covers 2020 to 2030</a>. </p>
<p>Canada has already been a key partner in <a href="https://www.skao.int/en/partners/prospective-members/388/canada#__otpm0">the SKA project for over 20 years</a>, making contributions to both the technical and scientific designs. There is no other existing or planned telescope like the SKAO, and not participating would have meant that Canadian astronomers would miss out. </p>
<h2>Canadian leadership</h2>
<p>Canadian astronomy, despite its small size, is a world leader. We already conduct research with radio astronomy facilities such as the <a href="https://chime-experiment.ca/en">CHIME</a> experiment near Penticton, B.C., <a href="https://almaobservatory.org/en/home/">Atacama Large Millimeter/submillimeter Array</a> in Chile and the <a href="https://science.nrao.edu/facilities/vla">Jansky Very Large Array</a> in New Mexico. Participation in the SKAO will allow us to keep making new discoveries, thanks to one of the largest Canadian investments in astronomy to date.</p>
<figure class="align-center ">
<img alt="a blue-lit circular device" src="https://images.theconversation.com/files/548372/original/file-20230914-19-joy01g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/548372/original/file-20230914-19-joy01g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=368&fit=crop&dpr=1 600w, https://images.theconversation.com/files/548372/original/file-20230914-19-joy01g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=368&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/548372/original/file-20230914-19-joy01g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=368&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/548372/original/file-20230914-19-joy01g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=463&fit=crop&dpr=1 754w, https://images.theconversation.com/files/548372/original/file-20230914-19-joy01g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=463&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/548372/original/file-20230914-19-joy01g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=463&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Large Hadron Collider at the European Organization for Nuclear Research where the Higgs boson was detected in 2012.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>Canada’s membership in the SKAO will allow Canadian companies to bid on shares of the work to be done for this billion-dollar mega science project. <a href="https://www.skao.int/en/partners/prospective-members/388/canada#__otpm5">Technologies developed for the project</a> will include computer hardware for digital signal processing and antenna dishes that can be mass produced of composite materials. These technologies may have applications in other industries. There is also the opportunity to strengthen Canada’s innovation culture and international reputation as a technology leader. </p>
<p>Once at full operation, the SKAO will produce a data firehose: <a href="https://www.skao.int/en/explore/big-data">300 petabytes</a>, or about half a million typical laptop hard drives, per year. Developing the computer hardware and software for processing the SKA data will be another technological win for Canada: the algorithms and know-how needed can be adapted for big data applications elsewhere, from climate modelling to epidemiological research.</p>
<h2>Future generations</h2>
<p>SKAO is not just another radio telescope. Construction will be <a href="https://www.space.com/square-kilometer-array-observatory-construction-begins">completed in 2029</a>, with significant Canadian contributions. Membership in SKAO will also attract and train the next generation of Canadian scientists and engineers. </p>
<p>The excitement of space attracts many youth to STEM careers, and those who choose to study astronomy will have the opportunity to work with cutting-edge hardware and vast amounts of data. Some of those graduates will go on to work in astronomy research, while others will apply their skills to careers in finance, health care or environmental monitoring and protection. This will help build Canada’s capacity for innovation in a technologically driven future.</p><img src="https://counter.theconversation.com/content/201341/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Pauline Barmby receives funding from the Natural Sciences and Engineering Research Council and the Canadian Space Agency and was co-chair of the Canadian Astronomical Society’s 2020 Long Range Plan panel.</span></em></p>Canada’s partnership in the world’s largest radio telescope, located in South Africa and Australia, creates new opportunities for research, but the benefits go beyond astronomy.Pauline Barmby, Professor, Physics & Astronomy, Western UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2107682023-08-21T12:24:46Z2023-08-21T12:24:46ZCaroline Herschel was England’s first female professional astronomer, but still lacks name recognition two centuries later<figure><img src="https://images.theconversation.com/files/543255/original/file-20230817-13660-rbgibr.jpg?ixlib=rb-1.1.0&rect=65%2C133%2C1998%2C1572&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Herschel Museum in Bath, England, has a new display of a handwritten draft of Caroline Herschel’s memoirs.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:The_Juvenile_instructor_(1866)_(14577404920).jpg">Internet Archive Book Images via Wikimedia Commons</a></span></figcaption></figure><p><a href="https://www.britannica.com/biography/Caroline-Lucretia-Herschel">Caroline Herschel</a>, the <a href="https://www.researchgate.net/publication/259930283_The_Hidden_Giants">first English professional female astronomer</a>, made contributions to astronomy that are still important to the field today. But even many astronomers may not recognize her name.</p>
<p>Most scientists care about the newest techniques, data and theories in their field, but they often know very little about the history of their discipline. <a href="https://scholar.google.com/citations?user=5CChghwAAAAJ&hl=en">Astronomers, like me,</a> are no exception.</p>
<p>It wasn’t until I taught an intro to astronomy class that I learned about Caroline. Now, thanks to a new display of her papers <a href="https://herschelmuseum.org.uk/">at the Herschel Museum</a> in Bath, England, others will get to learn about her too. Her story reflects not only the priorities of astronomy but also how credit is assigned in the field.</p>
<h2>Her path to astronomy</h2>
<p>Caroline Herschel, born in 1750, did not have an easy childhood. After a bout with typhus left her scarred at a young age, her family assumed that she would never marry and <a href="https://www.penguinrandomhouse.com/books/82017/the-age-of-wonder-by-richard-holmes/">treated her as an unpaid servant</a>. She was forced to complete household chores, despite showing a keen interest in learning from a young age. She eventually escaped her family to follow her older brother <a href="https://www.britannica.com/biography/William-Herschel">William Herschel</a>, whom she adored, to Bath.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/542891/original/file-20230815-25-k6lyuy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An illustration of two people, and man and a woman, leaning over a table. The man polishes a lens on the table. Other astronomical instruments are visible behind them." src="https://images.theconversation.com/files/542891/original/file-20230815-25-k6lyuy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/542891/original/file-20230815-25-k6lyuy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=870&fit=crop&dpr=1 600w, https://images.theconversation.com/files/542891/original/file-20230815-25-k6lyuy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=870&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/542891/original/file-20230815-25-k6lyuy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=870&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/542891/original/file-20230815-25-k6lyuy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1094&fit=crop&dpr=1 754w, https://images.theconversation.com/files/542891/original/file-20230815-25-k6lyuy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1094&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/542891/original/file-20230815-25-k6lyuy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1094&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Caroline Herschel worked with her brother William on many pursuits.</span>
<span class="attribution"><a class="source" href="https://upload.wikimedia.org/wikipedia/commons/c/c3/Sir_William_Herschel_and_Caroline_Herschel._Wellcome_V0002731_%28cropped%29.jpg">A. Diethe/Wellcome Images via Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Caroline was a somewhat unwilling astronomer at first. She didn’t become interested in astronomy until William was already thoroughly engrossed in the subject. Although <a href="https://doi.org/10.1038/013361a0">she spoke somewhat disparagingly</a> about how she followed her brother to different interests, including music and astronomy, Caroline <a href="https://doi.org/10.1038/013361a0">eventually acknowledged</a> her real interest in studying astronomical bodies.</p>
<p>Astronomers at the time were mainly interested in <a href="https://www.britannica.com/science/astronomy/Herschel-and-the-Milky-Way">finding new objects and mapping out the heavens</a> with precision. Using telescopes to look for new comets and nebulae was also popular. William Herschel became famous after his <a href="https://doi.org/10.1098/rstl.1781.0056">discovery of Uranus in 1781</a>, though he mistook the planet for a comet at first.</p>
<p>At the beginning of her career, Caroline worked as William’s assistant. She focused mostly on <a href="https://www.penguinrandomhouse.com/books/82017/the-age-of-wonder-by-richard-holmes/">astronomical instrumentation tasks</a>, like polishing telescope mirrors. She also <a href="https://press.princeton.edu/books/hardcover/9780691148335/discoverers-of-the-universe">helped copy catalogs and took careful notes</a> about William’s observations. But then she began to make her own observations.</p>
<h2>Searching the skies</h2>
<p>In 1782, Caroline began recording the positions of new objects in her own logbook. It was through this work that <a href="https://doi.org/10.48550/arXiv.1212.0809">she discovered several comets and nebulae</a>. On Aug. 1, 1782, <a href="https://doi.org/10.1098/rstl.1787.0001">she discovered a comet</a> – meaning she was the first to see it in a telescope with her own eyes. This was the <a href="https://herschelmuseum.org.uk/wp-content/uploads/2022/12/Herschel-Museum-buys-Caroline-Herschels-memoirs-FINAL.pdf">first comet discovery attributed to a woman</a>. She went on to <a href="https://www.britannica.com/biography/Caroline-Lucretia-Herschel">discover seven more comets</a> over the next 11 years.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/543257/original/file-20230817-7412-iuf5bh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A black and white portrait of an older lady wearing a ruffled bonnet, pointing at a paper. She's holding a magnifying glass." src="https://images.theconversation.com/files/543257/original/file-20230817-7412-iuf5bh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/543257/original/file-20230817-7412-iuf5bh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=768&fit=crop&dpr=1 600w, https://images.theconversation.com/files/543257/original/file-20230817-7412-iuf5bh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=768&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/543257/original/file-20230817-7412-iuf5bh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=768&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/543257/original/file-20230817-7412-iuf5bh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=965&fit=crop&dpr=1 754w, https://images.theconversation.com/files/543257/original/file-20230817-7412-iuf5bh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=965&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/543257/original/file-20230817-7412-iuf5bh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=965&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Caroline Herschel (1750−1848) was the first woman to receive a salary as a scientist.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:ETH-BIB-Herschel,_Caroline_(1750-1848)-Portrait-Portr_11026-092-SF.jpg">ETH Library via Wikimedia Commons</a></span>
</figcaption>
</figure>
<p>At the time of the Herschels’ work, it was the actual observation of an object that warranted public recognition, so Caroline was given credit only for the comets she saw through the telescope herself. For all of her other work, like recording and organizing all the data from William’s observations, she received less credit than William.</p>
<p>For instance, when Caroline took all of William’s observations and compiled them into a catalog, it was <a href="https://www.jstor.org/stable/41df1d85-a112-3847-84fe-5f10debf1250?seq=18">published under William’s name</a>. Caroline is mentioned only as an “assistant” in the paper.</p>
<p>Nonetheless, in recognition of her discoveries and her work as William’s assistant, King George III of England <a href="https://www.penguinrandomhouse.com/books/82017/the-age-of-wonder-by-richard-holmes/">granted Caroline a salary</a>, making her the first professional female astronomer. </p>
<p>Later in life, Caroline reorganized the same catalog in a more efficient way, according to how practicing astronomers interested in looking for comets <a href="https://press.princeton.edu/books/hardcover/9780691148335/discoverers-of-the-universe">actually observed the night sky</a>. This updated catalog was later used as the basis of the <a href="https://ui.adsabs.harvard.edu/abs/1888MmRAS..49....1D/abstract">New General Catalogue</a>, which <a href="https://doi.org/10.3847/2041-8213/aa91c9">astronomers still</a> <a href="https://www.nytimes.com/2017/10/16/science/ligo-neutron-stars-collision.html">use today</a> to organize the stars.</p>
<p>The Herschels also created the first – though not quite correct – <a href="https://doi.org/10.1098/rstl.1785.0012">map of our galaxy, the Milky Way</a>.</p>
<h2>Who gets the credit in astronomy?</h2>
<p>Recognition for scientific work within the astronomical community is pretty different now than it was in the Herschels’ day. In fact, most of the astronomers who receive credit today are those whose work looks a lot like Caroline’s – recording and organizing data about astronomical observations. </p>
<p>Astronomers seldom put their eyeballs up to a telescope eyepiece anymore, and many of the most important discoveries are made by <a href="https://theconversation.com/james-webb-space-telescope-an-astronomer-on-the-team-explains-how-to-send-a-giant-telescope-to-space-and-why-167516">telescopes in space</a>. But astronomers still need to be able to make sense of all the data from these telescopes. Catalogs like the ones Caroline made are important tools for doing so. </p>
<p>Most people today haven’t heard of Caroline Herschel. Despite having several astronomical objects – and <a href="https://mailchi.mp/ace3dfcbde8a/dedicated_launch">even a satellite</a> – <a href="https://doi.org/10.1007/978-3-540-29925-7_282">named after her</a>, she doesn’t have the same name recognition as the other astronomers of her time. Some of the lack of recognition is probably because her brother received all the credit for her catalog. Today, astronomers would give them both credit.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/543270/original/file-20230817-17-oq5i48.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Photograph of a cluster of stars" src="https://images.theconversation.com/files/543270/original/file-20230817-17-oq5i48.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/543270/original/file-20230817-17-oq5i48.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/543270/original/file-20230817-17-oq5i48.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/543270/original/file-20230817-17-oq5i48.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/543270/original/file-20230817-17-oq5i48.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/543270/original/file-20230817-17-oq5i48.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/543270/original/file-20230817-17-oq5i48.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The cluster of stars NGC 7789 is unofficially nicknamed ‘Caroline’s Rose’ in honor of Caroline Herschel.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Caroline%27s_Rose_Open_Cluster_(NGC7789).jpg">Anton Vakulenko via Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Herschel is just one in a long line of female astronomers who did not receive the credit they were due and whose work was used to justify prizes for male scientists instead. These issues aren’t just restricted to 18th-century science, but persist through modern astronomy as well. <a href="https://www.britannica.com/biography/Jocelyn-Bell-Burnell">Jocelyn Bell Burnell</a>, who discovered the first radio pulsar, was <a href="https://www.nature.com/articles/d41586-018-06210-w">left off the 1974 Nobel Prize</a>, and the award was <a href="https://theconversation.com/should-all-nobel-prizes-be-canceled-for-a-year-97996">instead granted to her Ph.D. adviser</a>. </p>
<p>Although astronomy has come a long way since the 18th century, astronomers still need to think carefully about how to fairly recognize the people who participate in scientific discoveries. Acknowledging the contributions of astronomers like Caroline Herschel is a small step toward giving credit where credit is due.</p>
<p><em>This article has been updated to acknowledge other women astronomers who preceded Herschel.</em></p><img src="https://counter.theconversation.com/content/210768/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kris Pardo does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Astronomer Caroline Herschel’s work discovering and cataloging astronomical objects in the 18th century is still used in the field today, but she didn’t always get her due credit.Kris Pardo, Assistant Professor of Physics and Astronomy, USC Dornsife College of Letters, Arts and SciencesLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2060552023-07-12T12:39:24Z2023-07-12T12:39:24ZA new, thin-lensed telescope design could far surpass James Webb – goodbye mirrors, hello diffractive lenses<figure><img src="https://images.theconversation.com/files/536371/original/file-20230707-21-kxopc5.jpeg?ixlib=rb-1.1.0&rect=44%2C44%2C1209%2C599&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A light, cheap space telescope design would make it possible to put many individual units in space at once.</span> <span class="attribution"><span class="source">Katie Yung, Daniel Apai /University of Arizona and AllThingsSpace /SketchFab</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Astronomers have discovered more than <a href="https://exoplanets.nasa.gov/discovery/exoplanet-catalog/">5,000 planets outside of the solar system</a> to date. The grand question is whether <a href="https://theconversation.com/to-search-for-alien-life-astronomers-will-look-for-clues-in-the-atmospheres-of-distant-planets-and-the-james-webb-space-telescope-just-proved-its-possible-to-do-so-184828">any of these planets are home to life</a>. To find the answer, astronomers will likely need <a href="https://nap.nationalacademies.org/catalog/26141/pathways-to-discovery-in-astronomy-and-astrophysics-for-the-2020s">more powerful telescopes</a> than exist today.</p>
<p>I am an <a href="https://scholar.google.com/citations?user=2SCIYjIAAAAJ&hl=en&oi=ao">astronomer who studies astrobiology</a> and planets around distant stars. For the last seven years, I have been co-leading a team that is developing a new kind of space telescope that could collect a hundred times more light than the <a href="https://theconversation.com/the-most-powerful-space-telescope-ever-built-will-look-back-in-time-to-the-dark-ages-of-the-universe-169603">James Webb Space Telescope</a>, the biggest space telescope ever built.</p>
<p>Almost all space telescopes, including Hubble and Webb, collect light using mirrors. Our proposed telescope, the <a href="https://nautilus-array.space/">Nautilus Space Observatory</a>, would replace large, heavy mirrors with a novel, thin lens that is much lighter, cheaper and easier to produce than mirrored telescopes. Because of these differences, it would be possible to launch many individual units into orbit and create a powerful network of telescopes.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/536355/original/file-20230707-21-3gvtcx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A blue planet with clouds." src="https://images.theconversation.com/files/536355/original/file-20230707-21-3gvtcx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/536355/original/file-20230707-21-3gvtcx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/536355/original/file-20230707-21-3gvtcx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/536355/original/file-20230707-21-3gvtcx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/536355/original/file-20230707-21-3gvtcx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/536355/original/file-20230707-21-3gvtcx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/536355/original/file-20230707-21-3gvtcx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Exoplanets, like TOI-700d shown in this artist’s conception, are planets beyond our solar system and are prime candidates in the search for life.</span>
<span class="attribution"><a class="source" href="https://www.jpl.nasa.gov/spaceimages/images/largesize/PIA23408_hires.jpg">NASA's Goddard Space Flight Center</a></span>
</figcaption>
</figure>
<h2>The need for larger telescopes</h2>
<p>Exoplanets – planets that orbit stars other than the Sun – are prime targets in the search for life. Astronomers need to use giant space telescopes that collect huge amounts of light to <a href="https://exoplanets.nasa.gov/discovery/missions/#first-planetary-disk-observed">study these faint and faraway objects</a>. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/536356/original/file-20230707-23-pdn1e5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A massive circular gold mirror with people standing in the foreground." src="https://images.theconversation.com/files/536356/original/file-20230707-23-pdn1e5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/536356/original/file-20230707-23-pdn1e5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=899&fit=crop&dpr=1 600w, https://images.theconversation.com/files/536356/original/file-20230707-23-pdn1e5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=899&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/536356/original/file-20230707-23-pdn1e5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=899&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/536356/original/file-20230707-23-pdn1e5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1130&fit=crop&dpr=1 754w, https://images.theconversation.com/files/536356/original/file-20230707-23-pdn1e5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1130&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/536356/original/file-20230707-23-pdn1e5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1130&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The James Webb Space Telescope is just barely able to search exoplanets for signs of life.</span>
<span class="attribution"><a class="source" href="http://jwst.nasa.gov/multimedia.html">NASA</a></span>
</figcaption>
</figure>
<p>Existing telescopes can detect exoplanets as small as Earth. However, it takes a lot more sensitivity to begin to learn about the chemical composition of these planets. Even Webb is just barely powerful enough to search <a href="https://doi.org/10.3847/1538-3881/ab21e0">certain exoplanets for clues of life</a> – namely <a href="https://theconversation.com/to-search-for-alien-life-astronomers-will-look-for-clues-in-the-atmospheres-of-distant-planets-and-the-james-webb-space-telescope-just-proved-its-possible-to-do-so-184828">gases in the atmosphere</a>. </p>
<p>The James Webb Space Telescope cost more than <a href="https://www.gao.gov/products/gao-18-273">US$8 billion and took over 20 years to build</a>. The next flagship telescope is not expected to fly before 2045 and is estimated to <a href="https://www.science.org/content/article/nasa-unveils-initial-plan-multibillion-dollar-telescope-find-life-alien-worlds">cost $11 billion</a>. These ambitious telescope projects are always expensive, laborious and produce a single powerful – but very specialized – observatory.</p>
<h2>A new kind of telescope</h2>
<p>In 2016, aerospace giant <a href="https://www.northropgrumman.com">Northrop Grumman</a> invited me and 14 other professors and NASA scientists – all experts on exoplanets and the search for extraterrestrial life – to Los Angeles to answer one question: What will exoplanet space telescopes look like in 50 years?</p>
<p>In our discussions, we realized that a major bottleneck preventing the construction of more powerful telescopes is the challenge of making larger mirrors and getting them into orbit. To bypass this bottleneck, a few of us came up with the idea of revisiting an old technology called diffractive lenses. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/536361/original/file-20230707-29-i85svw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A cross section of two lenses, with the one on the left showing a jagged surface and the one on the right a rounded surface." src="https://images.theconversation.com/files/536361/original/file-20230707-29-i85svw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/536361/original/file-20230707-29-i85svw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=897&fit=crop&dpr=1 600w, https://images.theconversation.com/files/536361/original/file-20230707-29-i85svw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=897&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/536361/original/file-20230707-29-i85svw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=897&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/536361/original/file-20230707-29-i85svw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1127&fit=crop&dpr=1 754w, https://images.theconversation.com/files/536361/original/file-20230707-29-i85svw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1127&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/536361/original/file-20230707-29-i85svw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1127&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Diffractive lenses, left, are much thinner compared to similarly powerful refractive lenses, right.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Fresnel_lens#/media/File:Fresnel_lens.svg">Pko/Wikimedia Commons</a></span>
</figcaption>
</figure>
<p>Conventional lenses use refraction to focus light. <a href="https://theconversation.com/can-rainbows-form-in-a-circle-fun-facts-on-the-physics-of-rainbows-202952">Refraction is when light changes direction</a> as it passes from one medium to another – it is the reason light bends when it enters water. In contrast, diffraction is when light bends around corners and obstacles. A cleverly arranged pattern of steps and angles on a glass surface can form a diffractive lens. </p>
<p>The first such lenses were invented by the French scientist Augustin-Jean Fresnel in 1819 to provide lightweight lenses for <a href="https://wwnorton.com/books/9780393350890">lighthouses</a>. Today, similar diffractive lenses can be found in many small-sized consumer optics – from <a href="https://global.canon/en/v-square/34.html">camera lenses</a> to <a href="https://doi.org/10.1889/1.2206112">virtual reality headsets</a>. </p>
<p>Thin, simple diffractive lenses are <a href="http://cplire.ru:8080/2902/1/OGRW_2014_Proceedings.pdf#page=77">notorious for their blurry images</a>, so they have never been used in astronomical observatories. But if you could improve their clarity, using diffractive lenses instead of mirrors or refractive lenses would allow a space telescope to be much cheaper, lighter and larger.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/536359/original/file-20230707-17-kdihhg.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A person holding a round, thin piece of glass." src="https://images.theconversation.com/files/536359/original/file-20230707-17-kdihhg.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/536359/original/file-20230707-17-kdihhg.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=389&fit=crop&dpr=1 600w, https://images.theconversation.com/files/536359/original/file-20230707-17-kdihhg.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=389&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/536359/original/file-20230707-17-kdihhg.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=389&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/536359/original/file-20230707-17-kdihhg.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=488&fit=crop&dpr=1 754w, https://images.theconversation.com/files/536359/original/file-20230707-17-kdihhg.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=488&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/536359/original/file-20230707-17-kdihhg.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=488&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">One of the benefits of diffractive lenses is that they can remain thin while increasing in diameter.</span>
<span class="attribution"><span class="source">Daniel Apai/University of Arizona</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>A thin, high-resolution lens</h2>
<p>After the meeting, I returned to the University of Arizona and decided to explore whether modern technology could produce diffractive lenses with better image quality. Lucky for me, <a href="https://profiles.arizona.edu/person/milster">Thomas Milster</a> – one of the world’s leading experts on diffractive lens design – works in the building next to mine. We formed a team and got to work.</p>
<p>Over the following two years, our team invented a new type of diffractive lens that required new manufacturing technologies to etch a complex pattern of tiny grooves onto a piece of clear glass or plastic. The specific pattern and shape of the cuts focuses incoming light to a single point behind the lens. The new design produces a <a href="https://doi.org/10.1364/OSAC.410187">near-perfect quality image</a>, far better than previous diffractive lenses. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/536358/original/file-20230707-25-gj9ryc.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A triangular piece of glass with subtle etchings reflecting in the light." src="https://images.theconversation.com/files/536358/original/file-20230707-25-gj9ryc.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/536358/original/file-20230707-25-gj9ryc.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/536358/original/file-20230707-25-gj9ryc.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/536358/original/file-20230707-25-gj9ryc.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/536358/original/file-20230707-25-gj9ryc.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/536358/original/file-20230707-25-gj9ryc.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/536358/original/file-20230707-25-gj9ryc.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A diffractive lens bends light using etchings and patterns on its surface.</span>
<span class="attribution"><span class="source">Daniel Apai/University of Arizona</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Because it is the surface texture of the lens that does the focusing, not the thickness, you can easily make the lens bigger while <a href="https://doi.org/10.1364/FIO.2020.JTu7A.1">keeping it very thin and lightweight</a>. Bigger lenses collect more light, and low weight means <a href="https://doi.org/10.3847/1538-3881/ab2631">cheaper launches to orbit</a> – both great traits for a space telescope.</p>
<p>In August 2018, our team produced the first prototype, a 2-inch (5-centimeter) diameter lens. Over the next five years, we further improved the image quality and increased the size. We are now completing a 10-inch (24-cm) diameter lens that will be more than 10 times lighter than a conventional refractive lens would be.</p>
<h2>Power of a diffraction space telescope</h2>
<p>This new lens design makes it possible to rethink how a space telescope might be built. In 2019, our team published a concept called the <a href="https://doi.org/10.3847/1538-3881/ab2631">Nautilus Space Observatory</a>. </p>
<p>Using the new technology, our team thinks it is possible to build a 29.5-foot (8.5-meter) diameter lens that would be only about 0.2 inches (0.5 cm) thick. The lens and support structure of our new telescope could weigh around 1,100 pounds (500 kilograms). This is more than three times lighter than a Webb–style mirror of a similar size and would be bigger than Webb’s 21-foot (6.5-meter) diameter mirror. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/536353/original/file-20230707-21-pbljxz.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A spherical object in space with a lens on one side." src="https://images.theconversation.com/files/536353/original/file-20230707-21-pbljxz.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/536353/original/file-20230707-21-pbljxz.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/536353/original/file-20230707-21-pbljxz.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/536353/original/file-20230707-21-pbljxz.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/536353/original/file-20230707-21-pbljxz.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/536353/original/file-20230707-21-pbljxz.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/536353/original/file-20230707-21-pbljxz.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The thin lens allowed the team to design a lighter, cheaper telescope, which they named the Nautilus Space Observatory.</span>
<span class="attribution"><span class="source">Daniel Apai/University of Arizona</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>The lenses have other benefits, too. First, they are <a href="https://doi.org/10.1117/12.2633573">much easier and quicker</a> <a href="https://theconversation.com/how-do-you-build-a-mirror-for-one-of-the-worlds-biggest-telescopes-49927">to fabricate than mirrors</a> and can be made en masse. Second, lens-based telescopes work well even when not aligned perfectly, making these telescopes easier to <a href="https://doi.org/10.1117/12.2633760">assemble</a> and fly in space than mirror-based telescopes, which require extremely precise alignment.</p>
<p>Finally, since a single Nautilus unit would be light and relatively cheap to produce, it would be possible to put dozens of them into orbit. Our current design is in fact not a single telescope, but a constellation of 35 individual telescope units.</p>
<p>Each individual telescope would be an independent, highly sensitive observatory able to collect more light than Webb. But the real power of Nautilus would come from turning all the individual telescopes toward a single target. </p>
<p>By combining data from all the units, Nautilus’ light-collecting power would equal a telescope nearly 10 times larger than Webb. With this powerful telescope, astronomers could search hundreds of exoplanets for atmospheric gases that may <a href="https://theconversation.com/to-search-for-alien-life-astronomers-will-look-for-clues-in-the-atmospheres-of-distant-planets-and-the-james-webb-space-telescope-just-proved-its-possible-to-do-so-184828">indicate extraterrestrial life</a>.</p>
<p>Although the Nautilus Space Observatory is still a long way from launch, our team has made a lot of progress. We have shown that all aspects of the technology work in small-scale prototypes and are now focusing on building a 3.3-foot (1-meter) diameter lens. Our next steps are to send a small version of the telescope to the edge of space on a high-altitude balloon.</p>
<p>With that, we will be ready to propose a revolutionary new space telescope to NASA and, hopefully, be on the way to exploring hundreds of worlds for signatures of life.</p><img src="https://counter.theconversation.com/content/206055/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Daniel Apai receives funding from NASA, NSF, and the Gordon and Betty Moore Foundation. He works for The University of Arizona.</span></em></p>Space telescopes are limited in size due to the difficulties and cost of getting into orbit. By revamping an old optical technology, researchers are working on a lightweight and thin telescope design.Daniel Apai, Associate Dean for Research and Professor of Astronomy and Planetary Sciences, University of ArizonaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2052652023-05-10T12:28:10Z2023-05-10T12:28:10ZAstronomers just saw a star eat a planet – an astrophysicist on the team explains the first-of-its-kind discovery<figure><img src="https://images.theconversation.com/files/525217/original/file-20230509-17-8m0pr7.jpg?ixlib=rb-1.1.0&rect=0%2C137%2C3460%2C2017&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">New research shows that the destructive merging of a star and a planet expels huge amounts of gas, as shown in this artist's impression.</span> <span class="attribution"><a class="source" href="https://www.nature.com/articles/d41586-023-01385-3">K. Miller/R. Hurt (Caltech/IPAC)</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>For the first time, astronomers have captured images that show a star consuming one of its planets. The star, named ZTF SLRN-2020, is located in the Milky Way galaxy, in the constellation Aquila. As the star swallowed its planet, the star brightened to 100 times its normal level, allowing the 26-person team of astronomers I worked with to <a href="https://doi.org/10.1038/s41586-023-05842-x">detect this event as it happened</a>.</p>
<p><a href="https://itc.cfa.harvard.edu/people/morgan-macleod">I am a theoretical astrophysicist</a>, and I developed the computer models that our team uses to interpret the data we collect from telescopes. Although we only see the effects on the star, not the planet directly, our team is confident that the event we witnessed was a star swallowing its planet. Witnessing such an event for the first time has confirmed the long-standing assumption that stars swallow their planets and has illuminated how this fascinating process plays out.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/524944/original/file-20230508-247807-drmefx.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A white domed building at sunset." src="https://images.theconversation.com/files/524944/original/file-20230508-247807-drmefx.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/524944/original/file-20230508-247807-drmefx.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/524944/original/file-20230508-247807-drmefx.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/524944/original/file-20230508-247807-drmefx.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/524944/original/file-20230508-247807-drmefx.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/524944/original/file-20230508-247807-drmefx.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/524944/original/file-20230508-247807-drmefx.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Zwicky Transient Facility in Southern California is one of the observatories that captured the flash of light caused by the star consuming its planet.</span>
<span class="attribution"><a class="source" href="https://www.ztf.caltech.edu/multimedia.html#">Caltech/Palomar</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<h2>Finding a flash in the dynamic night sky</h2>
<p>The team I work with searches for the bursts of light and gas that occur when two stars merge into a bigger, single star. To do this, we have been using data from the <a href="https://www.ztf.caltech.edu/">Zwicky Transient Facility</a>, a telescope located on Palomar Mountain in Southern California. It takes nightly images of broad swaths of the sky, and astronomers can then compare these images to find stars that change in brightness over time, or what are called astronomical transients.</p>
<p>Finding stars that change in brightness isn’t the challenge – it’s sorting out the cause behind any specific change to a star. As my colleague <a href="https://space.mit.edu/people/de-kishalay/">Kishalay De</a> likes to say, “There are plenty of things in the sky that go boom.” The trick to identifying stellar mergers is to combine visible light – like the data collected at Palomar – with infrared data from <a href="https://www.nasa.gov/mission_pages/WISE/main/index.html">NASA’s WISE space telescope</a>, which has been surveying the entire sky for the past decade.</p>
<p>In 2020, the star ZTF SLRN-2020 suddenly became 100 times brighter in visible light over just 10 days. It then slowly started to fade back toward its normal brightness. About nine months before, the same object started to emit a lot of infrared light, too. This is exactly what it looks like when two stars merge together, with one critical difference – everything was scaled down. The brightness and total energy of this event were about a thousand times lower than any of the merging stellar pairs astronomers had found to date. </p>
<h2>When a star swallows its planets</h2>
<p>The idea that stars could engulf some of their planets has been a long-standing assumption in astronomy. Astronomers have long known that when stars <a href="https://www.teachastronomy.com/textbook/Star-Birth-and-Death/Nuclear-Reactions-in-Main-Sequence-Stars/">run out of hydrogen in their cores</a>, they get brighter and begin to <a href="https://www.teachastronomy.com/textbook/Star-Birth-and-Death/Red-Giants/">increase in size</a>.</p>
<p>Many planets have orbits that are <a href="https://doi.org/10.5281/zenodo.6368226">smaller than the eventual size of their parent stars</a>. So, when a star runs out of fuel and starts to expand, the planets nearby are inevitably consumed.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/525243/original/file-20230509-43918-15gi7w.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A graph showing two lines increasing to a peak near the same time with one increasing over a much shorter period of time." src="https://images.theconversation.com/files/525243/original/file-20230509-43918-15gi7w.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/525243/original/file-20230509-43918-15gi7w.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=305&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525243/original/file-20230509-43918-15gi7w.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=305&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525243/original/file-20230509-43918-15gi7w.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=305&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525243/original/file-20230509-43918-15gi7w.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=383&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525243/original/file-20230509-43918-15gi7w.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=383&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525243/original/file-20230509-43918-15gi7w.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=383&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The star ZTF SLRN-2020 increased in brightness in both visible and infrared wavelengths of light, with the peak occurring on May 24, 2020.</span>
<span class="attribution"><span class="source">M. MacLeod</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Interpreting a stellar flash</h2>
<p>In the ZTF SLRN-2020 outburst, our team never saw the planet itself, only the brightening from when the star absorbed the planet. This is where combining theoretical models with the observational data allowed us to understand what the telescopes captured.</p>
<p>The merging of two stars into a single, bigger star is a <a href="https://doi.org/10.3847/1538-4357/835/2/282">dramatic event</a> that throws matter out into the stars’ surroundings. A large part of my career has focused on <a href="https://doi.org/10.3847/1538-4357/aacf08">modeling the way stellar gas moves</a> and crashes into itself and is expelled in these moments of intense interaction. </p>
<p>My work has shown that the total mass of matter ejected in a merging event is proportional to the <a href="https://doi.org/10.3847/1538-4357/ab89b6">size of the objects involved in the merger</a>. Merge two equally large stars and you see a huge disturbance. Merge one star with a much smaller companion and the event might throw out a tiny fraction of the total mass of the stars.</p>
<p>The energy released during ZTF SLRN-2020’s outburst was a thousand times lower than typical for a two-star merger. This implies that the object that merged with the star weighed a thousand times less than a normal star. This clue pointed our team toward a gas giant planet – like Jupiter in our own solar system, which weighs roughly a thousand times less than the Sun.</p>
<p>Compared to Jupiter, however, this planet must have <a href="https://doi.org/10.48550/arXiv.2210.15848">orbited much closer to the star</a>, with one revolution around the star only taking a few days. <a href="https://doi.org/10.1146/annurev-astro-082214-122246">About 1% of stars</a> share this configuration of a large planet orbiting incredibly close to its parent star. </p>
<p>Further, I think that this configuration of a big planet close to its star is important in generating the event our team saw. My past research suggests that smaller planets – or ones in more-distant orbits that only get consumed once a star has grown massively in size – might be <a href="https://doi.org/10.3847/2041-8213/aaa5fa">swallowed without a detectable flash</a>.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/nDi0JIRDXI0?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The planet around ZTF SLRN-2020 skimmed the stellar surface before eventually falling into the star.</span></figcaption>
</figure>
<h2>Learning from the real thing</h2>
<p>From our data and modeling for ZTF SLRN-2020, our team has been able to paint a much clearer picture of how stars and planets merge. First, the planet skims across the surface of the star for many years, slowly heating up and expelling material <a href="https://doi.org/10.1038/d41586-023-01385-3">from the star’s atmosphere</a>. As this gas expands and cools, some of it forms molecules and dust. This cloud of dust gives the star a progressively redder color and emits increasing amounts of infrared radiation.</p>
<p>In the case of ZTF SLRN-2020, the orbit of the planet shrank slowly at first, then faster and faster as the planet smashed through the denser layers of the star’s atmosphere. Eventually, in just a few final days, the planet plunged below the surface of the star and was torn apart by the heat and force of the collision. This rapid injection of energy supplied heat to power ZTF SLRN-2020’s 10-day, hundredfold increase in brightness. Following this climactic moment, the star began to fade, telling our team that the planet-swallowing process was over and that the star was beginning to go back to business as usual. </p>
<p>While the destructive event has passed, there is still much to be learned. Next week our team will start analyzing data from the <a href="https://webb.nasa.gov/">James Webb Space Telescope</a> in the hopes of learning about the chemistry of the gas that now surrounds ZTF SLRN-2020.</p><img src="https://counter.theconversation.com/content/205265/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Morgan MacLeod is grateful for support from the Clay Postdoctoral Fellowship at the Smithsonian Astrophysical Observatory and from the National Science Foundation. </span></em></p>Stars begin to expand when they run out of fuel and can become thousands of times larger, consuming any planets in the way. For the first time, astronomers have witnessed one such event.Morgan MacLeod, Postdoctoral Fellow in Theoretical Astrophysics, Harvard UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2042452023-05-05T17:04:27Z2023-05-05T17:04:27ZThe Euclid spacecraft will transform how we view the ‘dark universe’<figure><img src="https://images.theconversation.com/files/524112/original/file-20230503-26-6f6as6.jpg?ixlib=rb-1.1.0&rect=17%2C8%2C5973%2C2964&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Euclid is set to launch this year on a rocket built by SpaceX.</span> <span class="attribution"><a class="source" href="https://www.esa.int/ESA_Multimedia/Search?SearchText=euclid&result_type=images">Work performed by ATG under contract for ESA</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>The European Space Agency’s (ESA) <a href="https://www.esa.int/Science_Exploration/Space_Science/Euclid_overview">Euclid satellite</a> completed the first part of its long journey into space on May 1 2023, when it <a href="https://www.esa.int/Science_Exploration/Space_Science/Euclid/Euclid_arrives_at_launch_site">arrived in Florida on a boat from Italy</a>. It is scheduled to lift off on a Falcon 9 rocket, built by SpaceX, from Cape Canaveral in early July.</p>
<p>Euclid is designed to provide us with a better understanding of the “mysterious” components of our universe, known as dark matter and dark energy. </p>
<p>Unlike the normal matter we experience here on Earth, <a href="https://www.nasa.gov/audience/forstudents/9-12/features/what-is-dark-matter.html">dark matter</a> neither reflects nor emits light. It binds galaxies together and is thought to make up about 80% of all the mass in the universe. We’ve known about it for a century, but its true nature remains an enigma. </p>
<p><a href="https://science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy">Dark energy</a> is similarly puzzling. Astronomers have shown that the expansion of the universe over the last five billion years has been <a href="https://iopscience.iop.org/article/10.1086/300499/fulltext/">accelerating faster than expected</a>. Many believe <a href="https://iopscience.iop.org/article/10.1086/307221/meta">this acceleration</a> is driven by an unseen force, which has been dubbed dark energy. This makes up about 70% of the energy in the universe. </p>
<p>Euclid will map this “dark universe”, using a suite of scientific instruments to shed light on different aspects of dark energy and dark matter. </p>
<h2>A light in the dark</h2>
<p>After launch, Euclid will undertake a month-long journey to a region in space called the <a href="https://solarsystem.nasa.gov/resources/754/what-is-a-lagrange-point/">second Earth-Sun Lagrangian point</a>, which is five times further from us than the Moon. It’s where the gravitational pull of the Sun and the Earth balance out and provides a stable vantage point for Euclid to observe the universe. Euclid will join the <a href="https://webb.nasa.gov">James Webb Space Telescope (JWST)</a> at this point and will be the perfect companion to that amazing space observatory.</p>
<p>My involvement in Euclid began in 2007 when I was invited by ESA to participate in an independent concept advisory team to assess two competing mission proposals called SPACE and DUNE. </p>
<p>Both used different techniques, and therefore different instruments, to study the dark universe, and ESA was struggling to decide between them. Both were compelling concepts and our team decided that both had merit, especially to provide a vital cross-check between them. Euclid was thus <a href="https://sci.esa.int/web/cosmic-vision/-/42437-study-missions">born from the best of both concepts</a>.</p>
<p>Euclid is designed to study the whole universe so needs instruments with wide fields of view. The wider the field of view of the imaging instrument, the more of the universe it can observe. To do this, Euclid uses a relatively small telescope compared to JWST. In size, Euclid is roughly the size of a truck compared to the aircraft-sized JWST. But Euclid also carries some of the biggest digital cameras deployed in space with fields of view hundreds of times greater than JWST’s. </p>
<h2>Shapes and colours</h2>
<p>The <a href="https://arxiv.org/pdf/1608.08603.pdf">Euclid VIS (or visible) instrument</a>, built mostly in the UK, is designed to measure the positions and shapes of as many galaxies as possible to look for subtle correlations in this data caused by the gravitational lensing of the light, as it travels to us through the intervening dark matter. This gravitational lensing effect is weak, only one part in a hundred thousand for most galaxies, thus requiring lots of galaxies to see the effect in high definition. Thus VIS will produce Hubble telescope-like image quality over a third of the night sky. </p>
<p>VIS, however, can’t measure the colours of objects. This is needed to measure their distance through the <a href="https://www.esa.int/Science_Exploration/Space_Science/What_is_red_shift">redshift effect</a>, where light from those objects is shifted to longer, or redder, wavelengths in a way that relates to their distance from us. Some of this data will need to come from existing and planned ground-based observatories, but Euclid also carries the <a href="https://arxiv.org/pdf/2203.01650.pdf">NISP (Near-Infra Spectrometer and Photometer)</a> instrument which is specifically designed to measure the infrared colours and spectra, and therefore redshifts, for the most distant galaxies that Euclid will see. </p>
<p>To measure dark energy, NISP will exploit a relative new technique called <a href="https://svs.gsfc.nasa.gov/13768">Baryon Acoustic Oscillations (BAO)</a> that provides an accurate measurement of the expansion history of the universe over its last 10 billion years. That history is vital for testing possible models of dark energy including suggested modifications to Einstien’s Theory of General Relativity. </p>
<figure class="align-center ">
<img alt="The Whirlpool Galaxy, known as M51, and a companion galaxy." src="https://images.theconversation.com/files/524144/original/file-20230503-26-56rt5t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/524144/original/file-20230503-26-56rt5t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=416&fit=crop&dpr=1 600w, https://images.theconversation.com/files/524144/original/file-20230503-26-56rt5t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=416&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/524144/original/file-20230503-26-56rt5t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=416&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/524144/original/file-20230503-26-56rt5t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=523&fit=crop&dpr=1 754w, https://images.theconversation.com/files/524144/original/file-20230503-26-56rt5t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=523&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/524144/original/file-20230503-26-56rt5t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=523&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Euclid will gather information on the shapes and other properties of galaxies in the sky.</span>
<span class="attribution"><a class="source" href="https://esahubble.org/images/heic0506a/">NASA, ESA, S. Beckwith (STScI), and The Hubble Heritage Team (STScI/AURA)</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Treasure trove</h2>
<p>Such an experiment takes an army of scientists and not everyone is solely working on dark matter and dark energy. Like JWST, Euclid will be a treasure-trove of new discoveries in many areas of astronomy. The Euclid consortium needs hundreds of people to help develop the sophisticated software needed to merge the space data with the ground-based data, and extract, to high accuracy, the shapes and colours of billions of galaxies. </p>
<p>This software has also been checked and verified using some of the largest simulations of the universe that have ever been constructed. After arriving at L2, Euclid will undergo several months of testing, validation and calibration to ensure the instruments and telescope are working as expected. We are all familiar with such nervous waiting after the recent JWST launch. </p>
<p>Once ready, Euclid will embark on a five-year survey of 15,000 square degrees of the sky with about 2,000 scientists from across the world collecting results along the way. However, the true power of Euclid will only be realised once we have all this data together and analysed carefully. That could take another five years, taking us well into next decade before we have our final dark answers. The SpaceX launch therefore only feels like the half-way point in the Euclid story.</p>
<p>I will travel to Florida this summer to see the launch of Euclid. I will be joined by hundreds of my colleagues who have dedicated their careers to building this amazing telescope and experiment. Seeing the project come together in this way makes me proud to call myself a “Euclidian”.</p><img src="https://counter.theconversation.com/content/204245/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Bob Nichol previously received funding from UKSA as part of his leadership roles in the Euclid Consortium. He has not received any funding from UKSA since 2020.</span></em></p>A spacecraft set to launch this year will throw a spotlight on the mysterious ‘dark side’ of the universe.Robert Nichol, Pro Vice-Chancellor and Executive Dean, University of SurreyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2038192023-05-03T12:11:10Z2023-05-03T12:11:10ZMay 5, 2023, lunar eclipse will be a subtle show of astronomical wonder<figure><img src="https://images.theconversation.com/files/523890/original/file-20230502-16-holf94.jpg?ixlib=rb-1.1.0&rect=7%2C32%2C2381%2C973&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Penumbral lunar eclipses slightly darken the Moon.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Penumbral_Lunar_Eclipse_2020-01-10.jpg#/media/File:Penumbral_Lunar_Eclipse_2020-01-10.jpg">H. Raab/Wikipedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>On May 5, 2023, people around the world will <a href="https://eclipse.gsfc.nasa.gov/LEdecade/LEdecade2021.html">witness a a lunar eclipse</a> when the Earth gets between the Sun and the Moon and casts part of its shadow on the Moon.</p>
<p>The eclipse will be visible in Africa, Asia, Australia and large portions of Europe, though not in the U.S. this time around. This eclipse is not what some call a “blood moon,” as it will not turn red. Instead, the Moon will dim slightly as it passes through a <a href="https://earthsky.org/astronomy-essentials/what-is-a-penumbral-eclipse-of-the-moon/">lighter part of the Earth’s shadow</a> – called the penumbra.</p>
<p>I am the <a href="https://www.abramsplanetarium.org/Staff/Index.html">director of the Abrams Planetarium</a> at Michigan State University and it is part of my job to get people outside and looking up, and eclipses are some of the easiest to see. While the upcoming event will not be the most stunning celestial display, it is just the first of a number of eclipses occurring over the next year, and they all work in similar ways.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/522228/original/file-20230420-16-7nm8zk.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram showing the orientation of a lunar eclipse." src="https://images.theconversation.com/files/522228/original/file-20230420-16-7nm8zk.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/522228/original/file-20230420-16-7nm8zk.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/522228/original/file-20230420-16-7nm8zk.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/522228/original/file-20230420-16-7nm8zk.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/522228/original/file-20230420-16-7nm8zk.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/522228/original/file-20230420-16-7nm8zk.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/522228/original/file-20230420-16-7nm8zk.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A lunar eclipse occurs when the Moon passes through the Earth’s shadow.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Geometry_of_a_Lunar_Eclipse.svg#/media/File:Geometry_of_a_Lunar_Eclipse.svg">Sagredo/Wikimedia Commons</a></span>
</figcaption>
</figure>
<h2>How do eclipses work?</h2>
<p>Both lunar and solar eclipses depend on particular orientations of the Earth, Sun and Moon. A lunar eclipse occurs when the Earth’s shadow covers all or part of the Moon. This can only happen when the Moon is directly on the opposite side of the Earth from Sun, which is also when full moons occur.</p>
<p>Like the Earth, half of the Moon is illuminated by the Sun at any one time. When the Moon and the Sun are perfectly opposite each other, people on Earth can see the entire lit-up side, which looks like a round disc in the night sky.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/522227/original/file-20230420-24-zy1cng.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram showing how orientations of the Moon correspond to phases of the Moon." src="https://images.theconversation.com/files/522227/original/file-20230420-24-zy1cng.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/522227/original/file-20230420-24-zy1cng.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=183&fit=crop&dpr=1 600w, https://images.theconversation.com/files/522227/original/file-20230420-24-zy1cng.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=183&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/522227/original/file-20230420-24-zy1cng.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=183&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/522227/original/file-20230420-24-zy1cng.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=230&fit=crop&dpr=1 754w, https://images.theconversation.com/files/522227/original/file-20230420-24-zy1cng.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=230&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/522227/original/file-20230420-24-zy1cng.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=230&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Lunar eclipses can only occur during a full moon when the Moon is opposite the Sun.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Fases_lunars.png#/media/File:Moon_phases_en.jpg">Orion 8/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>If the Moon had a totally flat orbit, every full moon would be a lunar eclipse. But the Moon’s orbit is tilted by about 5 degrees relative to Earth’s orbit of the Sun. Because of this small tilt, most of the time a full moon ends up a little above or below the shadow cast by the Earth.</p>
<p>But twice in each monthlong lunar orbit, the Moon crosses through the same horizontal plane as the Earth and the Sun. If this happens during a full moon, the Sun, Earth and Moon will form a straight line and the Moon will pass through the Earth’s shadow, resulting in a lunar eclipse.</p>
<h2>The Earth’s shadow</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/523892/original/file-20230502-1446-ty2lbe.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A circular shadow on a wall with a dark center and lighter ring around it." src="https://images.theconversation.com/files/523892/original/file-20230502-1446-ty2lbe.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/523892/original/file-20230502-1446-ty2lbe.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=444&fit=crop&dpr=1 600w, https://images.theconversation.com/files/523892/original/file-20230502-1446-ty2lbe.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=444&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/523892/original/file-20230502-1446-ty2lbe.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=444&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/523892/original/file-20230502-1446-ty2lbe.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=558&fit=crop&dpr=1 754w, https://images.theconversation.com/files/523892/original/file-20230502-1446-ty2lbe.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=558&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/523892/original/file-20230502-1446-ty2lbe.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=558&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The shadow on the wall has a darker center surrounded by a lighter, but still shadowed, outer ring, just like the shadow cast by Earth.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Shadow_Blister_Effect.png#/media/File:Shadow_Blister_Effect.png">User4288/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>As the Sun shines light on Earth, Earth casts a shadow behind itself. But the darkness of shadows are not always uniform, and the shadow cast by the Earth is no exception. </p>
<p>The rays of light coming from a wide, or extended, light source – such as the Sun or a flashlight – don’t all come from the exact same location. Since the Sun is large, there can be quite a distance between the origin of rays of light heading toward Earth. </p>
<p>This difference in location means that when Earth blocks the light coming from one part of the Sun, it might not block out light coming from another location on the Sun. This results in <a href="http://www.differencebetween.net/science/difference-between-penumbra-and-umbra/">parts of Earth’s shadow that are darker</a> – the darkest part is where all light is blocked, while the lighter parts are because some light still makes it past the Earth.</p>
<p>A total lunar eclipse is when the Moon passes entirely through the darkest part, or umbra, of the Earth’s shadow. A partial lunar eclipse is when the umbra covers part of the Moon. The eclipse on May 5, 2023, is the last kind of eclipse where only the lighter part of the shadow will cover the Moon, which is why it is known as a penumbral lunar eclipse.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/522231/original/file-20230420-1202-8eu7lo.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A map showing regions of Earth where people can see the lunar eclipse." src="https://images.theconversation.com/files/522231/original/file-20230420-1202-8eu7lo.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/522231/original/file-20230420-1202-8eu7lo.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=264&fit=crop&dpr=1 600w, https://images.theconversation.com/files/522231/original/file-20230420-1202-8eu7lo.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=264&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/522231/original/file-20230420-1202-8eu7lo.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=264&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/522231/original/file-20230420-1202-8eu7lo.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=332&fit=crop&dpr=1 754w, https://images.theconversation.com/files/522231/original/file-20230420-1202-8eu7lo.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=332&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/522231/original/file-20230420-1202-8eu7lo.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=332&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The lunar eclipse on May 5, 2023, will be visible for most of Africa, Asia, Europe and Australia.</span>
<span class="attribution"><a class="source" href="https://eclipse.gsfc.nasa.gov/LEplot/LEplot2001/LE2023May05N.pdf">NASA</a></span>
</figcaption>
</figure>
<h2>How can you see the lunar eclipse?</h2>
<p>As long as you are on the night side of the Earth when a lunar eclipse happens, you can see it. The May 5 penumbral eclipse will be visible in most of Europe and Africa at moonrise, Asia and Australia will be able to see the entirety of the event in the middle of the night, and locations throughout the Pacific Ocean will be able to see it at moonset. </p>
<p>Lunar eclipses are relatively short, only lasting a few hours from start to finish. Totality, the part of the eclipse that is darkest, lasts about 30 to 60 minutes depending on how close to the center of the shadow you are. </p>
<p>For people in North and South America where the eclipse won’t be visible, there will be <a href="https://eclipse.gsfc.nasa.gov/LEdecade/LEdecade2021.html">plenty more in the next few years</a>. The next lunar eclipse will be Oct. 28, 2023, and will be a partial eclipse visible primarily in Africa, Europe and Asia. But the Americas will have their own penumbral eclipse on March 25, 2024, followed by a partial lunar eclipse on Sep. 18, 2024. </p>
<p>For those hoping to catch the next total lunar eclipse, they will have to wait until March 14, 2025, when a total lunar eclipse will be visible from the Americas, western Europe and western Africa.</p><img src="https://counter.theconversation.com/content/203819/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Shannon Schmoll does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Not all lunar eclipses are alike. An astronomer explains the science behind the slight dimming of the Moon on May 5, 2023.Shannon Schmoll, Director of the Abrams Planetarium, Michigan State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2043512023-05-03T12:10:32Z2023-05-03T12:10:32ZAI is helping astronomers make new discoveries and learn about the universe faster than ever before<figure><img src="https://images.theconversation.com/files/523645/original/file-20230501-18-4e90m3.jpg?ixlib=rb-1.1.0&rect=0%2C299%2C4895%2C3031&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The sky is big and full of information that AI tools can help astronomers unlock. </span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/paul-wild-observatory-under-starry-sky-royalty-free-image/637273906?phrase=telescope+with+milky+way&adppopup=true">Yuga Kurita/Moment via Getty Images</a></span></figcaption></figure><p>The famous first image of a black hole <a href="https://doi.org/10.3847/2041-8213/acc32d">just got two times sharper</a>. A research team used artificial intelligence to dramatically improve upon <a href="https://doi.org/10.3847/2041-8213/ab0ec7">its first image</a> from 2019, which now shows the black hole at the center of the M87 galaxy as darker and bigger than the first image depicted.</p>
<p>I’m an <a href="https://scholar.google.com/citations?user=OrRLRQ4AAAAJ&hl=en">astronomer</a> who studies and has written about <a href="https://wwnorton.com/books/9780393343861">cosmology</a>, <a href="https://wwnorton.com/books/9780393357509">black holes</a> and <a href="https://www.penguinrandomhouse.com/books/718149/worlds-without-end-by-chris-impey/">exoplanets</a>. Astronomers have been using AI for decades. In fact, in 1990, astronomers from the University of Arizona, where I am a professor, were among the <a href="https://www.datasciencecentral.com/the-evolution-of-astronomical-ai/">first to use a type of AI called a neural network</a> to study the shapes of galaxies. </p>
<p>Since then, AI has spread into every field of astronomy. As the technology has become more powerful, AI algorithms have begun helping astronomers tame massive data sets and discover new knowledge about the universe.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/523641/original/file-20230501-18-3sjj1h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A group of radio antennas pointed at the sky." src="https://images.theconversation.com/files/523641/original/file-20230501-18-3sjj1h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/523641/original/file-20230501-18-3sjj1h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/523641/original/file-20230501-18-3sjj1h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/523641/original/file-20230501-18-3sjj1h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/523641/original/file-20230501-18-3sjj1h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/523641/original/file-20230501-18-3sjj1h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/523641/original/file-20230501-18-3sjj1h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Astronomy is no longer limited to just optical images – radio telescopes produce huge amounts of data that researchers need to process.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/observatory-antenna-in-the-sunse-royalty-free-image/1309400138?phrase=astronomy+data&adppopup=true">Wenbin/Moment via Getty Images</a></span>
</figcaption>
</figure>
<h2>Better telescopes, more data</h2>
<p>As long as astronomy has been a science, it has involved trying to make sense of the multitude of objects in the night sky. That was relatively simple when the only tools were the naked eye or a simple telescope, and all that could be seen were a few thousand stars and a handful of planets.</p>
<p>A hundred years ago, Edwin Hubble used newly built telescopes to show that the universe is filled with not just stars and clouds of gas, <a href="https://www.nasa.gov/content/about-story-edwin-hubble">but countless galaxies</a>. As telescopes have continued to improve, the sheer number of celestial objects humans can see and the <a href="https://events.asiaa.sinica.edu.tw/school/20170904/talk/djorgovski1.pdf">amount of data</a> astronomers need to sort through have both grown exponentially, too.</p>
<p>For example, the soon-to-be-completed <a href="https://www.lsst.org/about">Vera Rubin Observatory</a> in Chile will make images so large that it would take 1,500 high-definition TV screens to view each one in its entirety. Over 10 years it is expected to generate 0.5 exabytes of data – about 50,000 times the amount of information held in all of the books contained within the Library of Congress. </p>
<p>There are 20 telescopes with mirrors larger than 20 feet (6 meters) in diameter. AI algorithms are the only way astronomers could ever hope to work through all of the data available to them today. There are a number of ways AI is proving useful in processing this data.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/523642/original/file-20230501-292-iuhviz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A sky filled with galaxies." src="https://images.theconversation.com/files/523642/original/file-20230501-292-iuhviz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/523642/original/file-20230501-292-iuhviz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=375&fit=crop&dpr=1 600w, https://images.theconversation.com/files/523642/original/file-20230501-292-iuhviz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=375&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/523642/original/file-20230501-292-iuhviz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=375&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/523642/original/file-20230501-292-iuhviz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=471&fit=crop&dpr=1 754w, https://images.theconversation.com/files/523642/original/file-20230501-292-iuhviz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=471&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/523642/original/file-20230501-292-iuhviz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=471&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">One of the earliest uses of AI in astronomy was to pick out the multitude of faint galaxies hidden in the background of images.</span>
<span class="attribution"><a class="source" href="https://flickr.com/photos/nasawebbtelescope/52777397541/">ESA/Webb, NASA & CSA, J. Rigby</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Picking out patterns</h2>
<p>Astronomy often involves looking for needles in a haystack. About 99% of the pixels in an astronomical image contain background radiation, light from other sources or the blackness of space – only 1% have the subtle shapes of faint galaxies. </p>
<p>AI algorithms – in particular, neural networks that use many interconnected nodes and are able to learn to recognize patterns – are perfectly suited for picking out the patterns of galaxies. Astronomers began <a href="https://doi.org/10.1111/j.1365-2966.2010.16713.x">using neural networks to classify galaxies</a> in the early 2010s. Now the algorithms <a href="https://www.nao.ac.jp/en/news/science/2020/20200811-subaru.html">are so effective</a> that they can classify galaxies with an accuracy of 98%.</p>
<p>This story has been repeated in other areas of astronomy. Astronomers working on SETI, the Search for Extraterrestrial Intelligence, use radio telescopes to look for signals from distant civilizations. Early on, radio astronomers scanned charts by eye to <a href="https://earthsky.org/space/wow-signal-explained-comets-antonio-paris/">look for anomalies</a> that couldn’t be explained. More recently, researchers harnessed 150,000 personal computers and 1.8 million citizen scientists to look for artificial <a href="https://www.nytimes.com/2020/03/23/science/seti-at-home-aliens.html">radio signals</a>. Now, researchers are using AI to sift through reams of data much more quickly and thoroughly than people can. This has allowed SETI efforts to cover more ground while also greatly reducing the <a href="https://doi.org/10.1038/s41550-022-01872-z">number of false positive signals</a>.</p>
<p>Another example is the search for exoplanets. Astronomers discovered most of the <a href="https://exoplanets.nasa.gov/">5,300 known exoplanets</a> by measuring a dip in the amount of light coming from a star <a href="https://exoplanets.nasa.gov/resources/2338/exoplanet-detection-transit-method/">when a planet passes in front of it</a>. AI tools can now pick out the signs of an exoplanet with <a href="https://doi.org/10.48550/arXiv.2011.14135">96% accuracy</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/523643/original/file-20230501-16-xeiogk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A planet near a dim red star." src="https://images.theconversation.com/files/523643/original/file-20230501-16-xeiogk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/523643/original/file-20230501-16-xeiogk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/523643/original/file-20230501-16-xeiogk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/523643/original/file-20230501-16-xeiogk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/523643/original/file-20230501-16-xeiogk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/523643/original/file-20230501-16-xeiogk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/523643/original/file-20230501-16-xeiogk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">AI tools can help astronomers discover new exoplanets like TRAPPIST-1 b.</span>
<span class="attribution"><a class="source" href="https://flickr.com/photos/nasawebbtelescope/52775409328/">NASA, ESA, CSA, Joseph Olmsted (STScI)</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Making new discoveries</h2>
<p>AI has proved itself to be excellent at identifying known objects – like galaxies or exoplanets – that astronomers tell it to look for. But it is also quite powerful at finding objects or phenomena that are theorized but have not yet been discovered in the real world.</p>
<p>Teams have used this approach to detect <a href="https://www.sciencedaily.com/releases/2023/02/230207144222.htm">new exoplanets</a>, learn about the <a href="https://www.quantamagazine.org/with-ai-astronomers-dig-up-the-stars-that-birthed-the-milky-way-20230328/">ancestral stars</a> that led to the formation and growth of the Milky Way, and predict the signatures of new types of <a href="https://cerncourier.com/a/gravitational-wave-astronomy-turns-to-ai/">gravitational waves</a>.</p>
<p>To do this, astronomers first use AI to convert theoretical models into observational signatures – including realistic levels of noise. They then use machine learning to sharpen the ability of AI to detect the predicted phenomena.</p>
<p>Finally, radio astronomers have also been using AI algorithms to sift through signals that don’t correspond to known phenomena. Recently a team from South Africa found a <a href="https://www.biznews.com/global-citizen/2023/04/06/machine-learnings-discovery-astronomy">unique object</a> that may be a remnant of the explosive merging of two supermassive black holes. If this proves to be true, the data will allow a new test of general relativity – Albert Einstein’s <a href="https://theconversation.com/why-does-gravity-pull-us-down-and-not-up-162141">description of space-time</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/523644/original/file-20230501-22-dihfie.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two side-by-side images of an orange circular haze around a dark center." src="https://images.theconversation.com/files/523644/original/file-20230501-22-dihfie.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/523644/original/file-20230501-22-dihfie.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=301&fit=crop&dpr=1 600w, https://images.theconversation.com/files/523644/original/file-20230501-22-dihfie.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=301&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/523644/original/file-20230501-22-dihfie.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=301&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/523644/original/file-20230501-22-dihfie.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=378&fit=crop&dpr=1 754w, https://images.theconversation.com/files/523644/original/file-20230501-22-dihfie.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=378&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/523644/original/file-20230501-22-dihfie.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=378&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The team that first imaged a black hole, at left, used AI to generate a sharper version of the image, at right, showing the black hole to be larger than originally thought.</span>
<span class="attribution"><a class="source" href="https://iopscience.iop.org/article/10.3847/1538-4357/acaa9a/meta">Medeiros et al 2023</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Making predictions and plugging holes</h2>
<p>As in many areas of life recently, generative AI and large language models like ChatGPT are also making waves in the astronomy world.</p>
<p>The team that created the first image of a black hole in 2019 used a <a href="https://doi.org/10.3847/2041-8213/acc32d">generative AI to produce its new image</a>. To do so, it first taught an AI how to recognize black holes by feeding it simulations of many kinds of black holes. Then, the team used the AI model it had built to fill in gaps in the massive amount of data collected by the radio telescopes on the black hole M87. </p>
<p>Using this simulated data, the team was able to create a new image that is two times sharper than the original and is fully consistent with the predictions of general relativity.</p>
<p>Astronomers are also turning to AI to help tame the complexity of modern research. A team from the Harvard-Smithsonian Center for Astrophysics created a <a href="https://doi.org/10.48550/arXiv.2212.00744">language model called astroBERT</a> to read and organize 15 million scientific papers on astronomy. Another team, based at NASA, has even proposed using AI to <a href="https://www.technologyreview.com/2021/09/20/1035890/ai-predict-astro2020-decadal-survey/">prioritize astronomy projects</a>, a process that astronomers engage in every 10 years.</p>
<p>As AI has progressed, it has become an essential tool for astronomers. As telescopes get better, as data sets get larger and as AIs continue to improve, it is likely that this technology will play a central role in future discoveries about the universe.</p><img src="https://counter.theconversation.com/content/204351/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Chris Impey receives funding from the National Science Foundation and Epic Games.</span></em></p>Artificial intelligence tools are making waves in almost every aspect of life, and astronomy is no different. An astronomer explains the history and future of AI in understanding the universe.Chris Impey, University Distinguished Professor of Astronomy, University of ArizonaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1917722023-04-06T07:04:07Z2023-04-06T07:04:07ZA ‘next-generation’ gamma-ray observatory is underway to probe the extreme Universe<figure><img src="https://images.theconversation.com/files/512377/original/file-20230227-4042-xvl5v5.jpg?ixlib=rb-1.1.0&rect=17%2C0%2C5716%2C3837&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">LST-1 prototype in La Palma, Spain.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/cta_observatory/50018704248/in/album-72157671493684827/">Tomohiro Inada/CTA</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>Long gone are the days when astronomers only studied the skies with simple optical telescopes. Today, unveiling the mysteries of the Universe involves ever-larger and more complex facilities that detect things like gravitational waves and different forms of electromagnetic radiation – the spectrum of energy that includes visible light and X-rays.</p>
<p>One particularly specialised branch of astronomy is gamma-ray astronomy. It does what is says on the tin, searching for <a href="https://www.space.com/gamma-rays-explained">gamma rays</a>, which are the most energetic photons (light particles) on the electromagnetic spectrum. In fact, they are <a href="https://www.britannica.com/science/electromagnetic-radiation/Gamma-rays">millions of times more energetic</a> than the light we can see.</p>
<p>In astronomy, gamma rays are produced by some of the hottest, most energetic events in the universe, such as star explosions and <a href="https://theconversation.com/like-a-spinning-top-wobbling-jets-from-a-black-hole-thats-feeding-on-a-companion-star-116067">black holes violently “feeding” on surrounding matter</a>. While gamma rays are now linked to dozens of different types of sources, in many cases we still don’t know conclusively what kinds of energetic particles are creating these rays.</p>
<p>Excitingly, gamma-ray astronomy is due to get a massive leg up with a new facility. Once the globally distributed <a href="https://www.cta-observatory.org">Cherenkov Telescope Array</a> (CTA) is complete, it will view the gamma-ray sky with ten times more sensitivity than what’s currently possible.</p>
<p>With more than 60 telescopes, the CTA is expected to provide deep insight into the nature of dark matter – an invisible, hypothetical type of matter making up about 85% of the mass of the Universe. The array could also help solve one of the longest-running mysteries in astronomy: where cosmic ray particles (energetic nuclei and electrons in our galaxy and beyond) come from. Gamma rays are linked to these particles, providing a means to trace them.</p>
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Read more:
<a href="https://theconversation.com/why-do-astronomers-believe-in-dark-matter-122864">Why do astronomers believe in dark matter?</a>
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<h2>Flashes from outer space</h2>
<p>Gamma-ray astronomy was born <a href="https://imagine.gsfc.nasa.gov/science/toolbox/gamma_ray_astronomy1.html">in the early 1960s</a> as space-based satellites were developed to look for energetic radiation from outer space.</p>
<p>NASA’s Fermi mission, launched in 2008 to a low-Earth orbit, has so far catalogued <a href="https://fermi.gsfc.nasa.gov/ssc/data/access/lat/10yr_catalog/">several thousand gamma-ray sources</a>. The Fermi spacecraft continues to provide 24-hour live coverage of the sky, measuring gamma rays with energies reaching several 1,000 giga-electron volts in energy. That’s about one trillion times the energy of visible light.</p>
<p>To study gamma rays with even higher energies, we need to use ground-based methods. Although Earth’s atmosphere shields us against radiation from outer space, we can still detect the secondary effects of this shielding on the ground. </p>
<p>That’s because when a gamma ray interacts with Earth’s atmosphere, it sparks an electromagnetic cascade or “air shower” of more than a billion secondary particles. These particles are mostly electrons and their anti-matter partners, called positrons. These air showers contribute about 30-50% of the natural radiation we experience in our lives.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/512372/original/file-20230227-1701-jolgvd.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A chart illustrating how gamma rays produce Cherenkov light when hitting the atmosphere" src="https://images.theconversation.com/files/512372/original/file-20230227-1701-jolgvd.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/512372/original/file-20230227-1701-jolgvd.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=435&fit=crop&dpr=1 600w, https://images.theconversation.com/files/512372/original/file-20230227-1701-jolgvd.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=435&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/512372/original/file-20230227-1701-jolgvd.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=435&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/512372/original/file-20230227-1701-jolgvd.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=547&fit=crop&dpr=1 754w, https://images.theconversation.com/files/512372/original/file-20230227-1701-jolgvd.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=547&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/512372/original/file-20230227-1701-jolgvd.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=547&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">CTA won’t be detecting gamma rays directly. It will pick up Cherenkov light, the blue flash of light resulting from gamma rays interacting with Earth’s atmosphere.</span>
<span class="attribution"><a class="source" href="https://www.eso.org/public/australia/images/eso1841x/">CTAO/ESO</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Making the invisible visible</h2>
<p>While nothing can go faster than the speed of light in a vacuum, charged particles such as electrons and positrons (anti-electrons) can actually move faster than light when moving through air. </p>
<p>When this happens, a shockwave is created as a flash of blue and ultraviolet light. This flash, called Cherenkov radiation, is named after Soviet physicist Pavel Cherenkov who first detected the phenomenon in 1934 (and received the <a href="https://www.nobelprize.org/prizes/physics/1958/cerenkov/facts/">1958 Nobel Prize in Physics</a> for it alongside two colleagues). The blue glow of Cherenkov radiation can be seen in water cooling ponds surrounding nuclear power reactors.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/512371/original/file-20230227-2341-a0usyn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A concrete room with a circular hole in the middle surrounded with railings, with blue glowing water inside" src="https://images.theconversation.com/files/512371/original/file-20230227-2341-a0usyn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/512371/original/file-20230227-2341-a0usyn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/512371/original/file-20230227-2341-a0usyn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/512371/original/file-20230227-2341-a0usyn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/512371/original/file-20230227-2341-a0usyn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/512371/original/file-20230227-2341-a0usyn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/512371/original/file-20230227-2341-a0usyn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The blue glow seen in the water cooling the core of a nuclear reactor is known as Cherenkov radiation.</span>
<span class="attribution"><span class="source">Parilov/Shutterstock</span></span>
</figcaption>
</figure>
<p>At ground level, telescopes with large mirrors and sensitive cameras can detect the Cherenkov light produced by a gamma ray striking our atmosphere. These cameras need just about ten nanoseconds to capture a Cherenkov flash against the bright background of starlight and moonlight. </p>
<p>The first Cherenkov telescopes were developed in the 1960s. After many variants, it was the Whipple Telescope in the United States that in <a href="https://ui.adsabs.harvard.edu/abs/1989ApJ...342..379W/abstract">1989 discovered gamma-ray photons</a> coming from the Crab Nebula.</p>
<p>This was the first time gamma rays with energies of more than 1,000 giga-electron volts (or 1 tera-electron-volt, TeV) were detected. Thus, tera-electron-volt gamma-ray astronomy was born.</p>
<h2>Searching for the extremes</h2>
<p>Today, all three of the world’s best TeV gamma-ray facilities – <a href="https://www.mpi-hd.mpg.de/hfm/HESS/">HESS</a> in Namibia, <a href="https://www.mpp.mpg.de/forschung/magic">MAGIC</a> in La Palma, Spain and <a href="https://veritas.sao.arizona.edu/">VERITAS</a> in Arizona – have discovered more than 200 TeV <a href="http://tevcat.uchicago.edu/">gamma-ray sources</a>. These powerful rays are linked to cosmic regions of particle acceleration, such as pulsars, supernova remnants, massive star clusters, and supermassive black holes in the Milky Way and other galaxies. </p>
<p>HESS has shown our Milky Way galaxy is rich in TeV gamma-ray “light”, including <a href="https://theconversation.com/supermassive-black-holes-could-be-a-source-of-mysterious-cosmic-rays-56357">in the centre of the galaxy</a>.</p>
<p>TeV gamma-rays are also seen from <a href="https://theconversation.com/a-collapsing-star-in-a-distant-galaxy-fired-out-some-of-the-most-energetic-gamma-rays-ever-seen-127114">mysterious gamma-ray bursts</a> and other fleeting, transient events. These are now informing our understanding of the extreme conditions in which gamma rays are created.</p>
<p>The next-generation CTA will use the lessons learnt from HESS, VERITAS and MAGIC, by extending the number of telescopes deployed on the ground to over 60 telescopes. CTA will also use a combination of three different telescope sizes optimised for three gamma-ray energy bands, providing unprecedented performance and “sharpness”.</p>
<p>It will have arrays at two sites on the ground: one in Paranal, Chile (51 telescopes) in the Southern Hemisphere, and one in La Palma (13 telescopes) in the Northern Hemisphere.</p>
<p>CTA has attracted membership from more than 1,000 scientists, including Australian scientists from seven universities. It’s progressing well, with the first northern telescope already detecting gamma rays from the Crab Nebula and several gamma-ray flares from <a href="https://astronomerstelegram.org/?read=14783">active galaxies powered by supermassive black holes</a>.</p>
<p>Within a few years we expect to see the first southern telescopes also detecting gamma rays, yielding many more discoveries. With CTA, we will have new insights into where extreme particle acceleration is taking place in our Milky Way.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/new-era-of-astronomy-uncovers-clues-about-the-cosmos-100155">New era of astronomy uncovers clues about the cosmos</a>
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<img src="https://counter.theconversation.com/content/191772/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gavin Rowell receives funding from the Australian Research Council to support the Cherenkov Telescope Array.</span></em></p>The most energetic events in the universe shower us with unbelievably energetic particles of light. Capturing these can help us to solve some enticing cosmic mysteries.Gavin Rowell, Professor in High Energy Astrophyics, University of AdelaideLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1996882023-04-05T15:45:25Z2023-04-05T15:45:25ZAstronomers used machine learning to mine data from South Africa’s MeerKAT telescope: what they found<figure><img src="https://images.theconversation.com/files/515439/original/file-20230315-28-t0q61o.jpg?ixlib=rb-1.1.0&rect=94%2C111%2C715%2C558&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">SAURON: radio intensity (purple) from MeerKAT overlaid on an optical image from the Dark Energy Survey.</span> <span class="attribution"><span class="source">Michelle Lochner / The Dark Energy Survey Collaboration 2005</span></span></figcaption></figure><p>New telescopes with unprecedented sensitivity and resolution are being unveiled around the world – and beyond. Among them are the <a href="https://giantmagellan.org/">Giant Magellan Telescope</a> under construction in Chile, and the <a href="https://webb.nasa.gov/">James Webb Space Telescope</a>, which is parked a million and a half kilometres out in space. </p>
<p>This means there is a wealth of data available to scientists that simply wasn’t there before. The raw data off just a single observation from the <a href="https://www.sarao.ac.za/science/meerkat/">MeerKAT radio telescope</a> in South Africa’s Northern Cape province can measure a terabyte. That’s enough to fill a laptop computer’s hard drive. <a href="https://theconversation.com/a-big-moment-for-africa-why-the-meerkat-and-astronomy-matter-99714">MeerKAT</a> is an array of 64 large antenna dishes. It uses radio signals from space to study the evolution of the universe and everything it contains – galaxies, for example. Each dish is said to generate as much <a href="https://www.sarao.ac.za/science/meerkat/about-meerkat/">data in one second</a> as you’d find on a DVD.</p>
<p><a href="https://www.britannica.com/technology/machine-learning">Machine learning</a> is helping astronomers to work through this data quickly and more accurately than poring over it manually. Perhaps surprisingly, despite increasing reliance on computers, up until recently the discovery of rare or new astrophysical phenomena has completely relied on human inspection of the data. </p>
<p>Machine learning is essentially a set of algorithms designed to automatically learn patterns and models from data. Because we astronomers aren’t sure what we’re going to find – we don’t know what we don’t know – we also design algorithms to look out for anomalies that don’t fit known parameters or “labels”.</p>
<p>This approach allowed my colleagues and I <a href="https://academic.oup.com/mnras/advance-article-abstract/doi/10.1093/mnras/stad074/6985618?redirectedFrom=fulltext">to spot</a> a previously overlooked object in data from MeerKAT. It sits some seven billion light years from Earth (a light year is a measure of how far light would travel in a year). From what we know of the object so far, it has many of the makings of what’s known as an Odd Radio Circle (ORC). </p>
<p>Odd Radio Circles are identifiable by their <a href="https://astronomy.com/news/2022/05/understanding-the-origins-of-orcs-odd-radio-circles">strange, ring-like structure</a>. Only a handful of these circles have been detected since the first discovery in 2019, so not much is known about them yet.</p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/combined-power-of-two-telescopes-is-helping-crack-the-mystery-of-eerie-rings-in-the-sky-180595">Combined power of two telescopes is helping crack the mystery of eerie rings in the sky</a>
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<p>In a new <a href="https://academic.oup.com/mnras/advance-article-abstract/doi/10.1093/mnras/stad074/6985618?redirectedFrom=fulltext">paper</a> we outline the features of our potential Odd Radio Circle, which we’ve named SAURON (a Steep and Uneven Ring Of Non-thermal Radiation). SAURON is, to our knowledge, the first scientific discovery made in MeerKAT data with machine learning. (There have been a handful of other discoveries assisted by machine learning in astronomy.)</p>
<p>Not only is discovering something new incredibly exciting, new discoveries are critical for challenging our understanding of the <a href="https://www.britannica.com/science/Cosmos-astronomy">cosmos</a>. These new objects may match our theories of how galaxies form and evolve, or we may need to change how we see the universe. New discoveries of anomalous astrophysical objects help science to make progress. </p>
<h2>Identifying anomalies</h2>
<p>We spotted SAURON in data from the <a href="https://arxiv.org/abs/2111.05673">MeerKAT Galaxy Cluster Legacy Survey</a>. The survey is a programme of observations conducted with South Africa’s MeerKAT telescope, a precursor to the <a href="https://www.skao.int/">Square Kilometre Array</a>. The array is a global project to build the world’s largest and most sensitive radio telescope within the coming decade, co-located in South Africa and Australia. </p>
<p>The survey was conducted between June 2018 and June 2019. It zeroed in on some 115 galaxy clusters, each made up of hundreds or even thousands of galaxies.</p>
<p>That’s a lot of data to sift through – which is where machine learning comes in. </p>
<p>We developed and used a coding framework which we called <a href="https://arxiv.org/abs/2010.11202">Astronomaly</a> to sort through the data. Astronomaly ranked unknown objects according to an anomaly scoring system. The human team then manually evaluated the 200 anomalies that interested us most. Here, we drew on vast collective expertise to make sense of the data. </p>
<p>It was during this part of the process that we identified SAURON. Instead of having to look at 6,000 individual images, we only had to look through the first 60 that Astronomaly flagged as anomalous to pick up SAURON. </p>
<p>But the question remains: what, exactly, have we found?</p>
<h2>Is SAURON an Odd Radio Circle?</h2>
<p>We know very little about Odd Radio Circles. It is currently thought that their bright, blast-like emission is the wreckage of a huge <a href="https://theconversation.com/odd-radio-circles-that-baffled-astronomers-are-likely-explosions-from-distant-galaxies-178290">explosion</a> in their host galaxies.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/517713/original/file-20230327-23-vb272r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Purple roughly circular shape on dark background" src="https://images.theconversation.com/files/517713/original/file-20230327-23-vb272r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/517713/original/file-20230327-23-vb272r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=446&fit=crop&dpr=1 600w, https://images.theconversation.com/files/517713/original/file-20230327-23-vb272r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=446&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/517713/original/file-20230327-23-vb272r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=446&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/517713/original/file-20230327-23-vb272r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=561&fit=crop&dpr=1 754w, https://images.theconversation.com/files/517713/original/file-20230327-23-vb272r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=561&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/517713/original/file-20230327-23-vb272r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=561&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">SAURON.</span>
<span class="attribution"><span class="source">Michelle Lochner</span></span>
</figcaption>
</figure>
<p>The name SAURON captures the fundamentals of the object’s make-up. “Steep” refers to its spectral slope, indicating that at higher radio frequencies the “source” (or object) very quickly grows fainter. “Ring” refers to the shape. And the “Non-Thermal Radiation” refers to the type of radiation, suggesting that there must be particles accelerating in powerful magnetic fields. SAURON is at least 1.2 million light years across, about 20 times the size of the Milky Way.</p>
<p>But SAURON doesn’t tick all the right boxes for us to say that it’s definitely an Odd Radio Circle. We detected a host galaxy but can find no evidence of radio emissions with the wavelengths and frequency that match those of host galaxies of the other known ORCs. </p>
<p>And even though SAURON has a number of features in common with Odd Radio Circle1 – the first Odd Radio Circle spotted – it differs in others. Its strange shape and its oddly behaving magnetic fields don’t align well with the main structure.</p>
<p>One of the most exciting possibilities is that SAURON is a remnant of the explosive merger of two supermassive black holes. These are incredibly dense objects at the centre of galaxies such as our Milky Way that could cause a massive explosion when galaxies collide. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-were-probing-the-secrets-of-a-giant-black-hole-at-our-galaxys-centre-108181">How we're probing the secrets of a giant black hole at our galaxy's centre</a>
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</em>
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<h2>More to come</h2>
<p>More investigation is required to unravel the mystery. Meanwhile, machine learning is quickly becoming an indispensable tool to find more strange objects by sorting through enormous datasets from telescopes. With this tool, we can expect to unveil more of what the universe is hiding.</p><img src="https://counter.theconversation.com/content/199688/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michelle Lochner receives funding from the National Research Foundation and the Department of Science and Innovation. </span></em></p>Machine learning is becoming an indispensable tool in astronomy by sorting through enormous datasets from telescopes.Michelle Lochner, Staff Scientist at the South African Radio Astronomy Observatory and Senior Lecturer in Astronomy, University of the Western CapeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2016222023-03-16T12:36:48Z2023-03-16T12:36:48ZWater in space – a ‘Goldilocks’ star reveals previously hidden step in how water gets to planets like Earth<figure><img src="https://images.theconversation.com/files/515568/original/file-20230315-1821-gn9l6v.jpg?ixlib=rb-1.1.0&rect=28%2C45%2C1249%2C1038&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The star system V883 Orionis contains a rare star surrounded by a disk of gas, ice and dust.</span> <span class="attribution"><a class="source" href="http://www.eso.org/public/images/eso1626a/">A. Angelich (NRAO/AUI/NSF)/ALMA (ESO/NAOJ/NRAO)</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Without water, life on Earth could not exist as it does today. Understanding the history of water in the universe is critical to understanding how planets like Earth come to be.</p>
<p>Astronomers typically refer to the journey water takes from its formation as individual molecules in space to its resting place on the surfaces of planets as “the water trail.” The trail starts in the interstellar medium with hydrogen and oxygen gas and ends with oceans and ice caps on planets, with icy moons orbiting gas giants and icy comets and asteroids that orbit stars. The beginnings and ends of this trail are easy to see, but the middle has remained a mystery.</p>
<p><a href="https://www.cv.nrao.edu/%7Ejtobin/">I am an astronomer</a> who studies the formation of stars and planets using observations from radio and infrared telescopes. In a new paper, my colleagues and I describe the <a href="https://www.nature.com/articles/s41586-022-05676-z">first measurements ever made</a> of this previously hidden middle part of the water trail and what these findings mean for the water found on planets like Earth.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/515526/original/file-20230315-18-7eqg1b.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="The progression of a star system from a cloud of dust and gas into a mature star with orbiting planets." src="https://images.theconversation.com/files/515526/original/file-20230315-18-7eqg1b.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/515526/original/file-20230315-18-7eqg1b.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/515526/original/file-20230315-18-7eqg1b.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/515526/original/file-20230315-18-7eqg1b.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/515526/original/file-20230315-18-7eqg1b.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/515526/original/file-20230315-18-7eqg1b.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/515526/original/file-20230315-18-7eqg1b.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Star and planet formation is an intertwined process that starts with a cloud of molecules in space.</span>
<span class="attribution"><a class="source" href="https://www.nrao.edu/pr/2012/clumpcores/">Bill Saxton, NRAO/AUI/NSF</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>How planets are formed</h2>
<p>The formation of stars and planets is intertwined. The so-called “emptiness of space” – or the interstellar medium – in fact contains <a href="https://doi.org/10.1146/annurev.aa.32.090194.001203">large amounts of gaseous hydrogen</a>, smaller amounts of other gasses and <a href="https://doi.org/10.1086/162480">grains of dust</a>. Due to gravity, some pockets of the interstellar medium will become <a href="https://doi.org/10.1086/311687">more dense as particles attract each other</a> and form clouds. As the density of these clouds increases, atoms begin to collide more frequently and <a href="https://doi.org/10.1086/381775">form larger molecules</a>, including water that forms <a href="https://doi.org/10.1080/0144235X.2015.1046679">on dust grains and coats the dust in ice</a>.</p>
<p>Stars begin to form when parts of the collapsing cloud reach a certain density and heat up enough to start fusing hydrogen atoms together. Since only a small fraction of the gas initially collapses into the newborn protostar, the rest of the gas and dust <a href="https://doi.org/10.48550/arXiv.1001.1404">forms a flattened disk of material</a> circling around the spinning, newborn star. Astronomers call this a proto-planetary disk.</p>
<p>As icy dust particles collide with each other inside a proto-planetary disk, <a href="https://doi.org/10.1051/0004-6361/200811158">they begin to clump together</a>. The process continues and eventually forms the familiar objects of space like asteroids, comets, rocky planets like Earth and gas giants like Jupiter or Saturn.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/515633/original/file-20230315-3008-q4peeq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A cloudy filament against a backdrop of stars." src="https://images.theconversation.com/files/515633/original/file-20230315-3008-q4peeq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/515633/original/file-20230315-3008-q4peeq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=679&fit=crop&dpr=1 600w, https://images.theconversation.com/files/515633/original/file-20230315-3008-q4peeq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=679&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/515633/original/file-20230315-3008-q4peeq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=679&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/515633/original/file-20230315-3008-q4peeq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=854&fit=crop&dpr=1 754w, https://images.theconversation.com/files/515633/original/file-20230315-3008-q4peeq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=854&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/515633/original/file-20230315-3008-q4peeq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=854&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Gas and dust can condense into clouds, like the Taurus Molecular Cloud, where collisions between hydrogen and oxygen can form water.</span>
<span class="attribution"><a class="source" href="http://www.eso.org/public/images/eso1209a/">ESO/APEX (MPIfR/ESO/OSO)/A. Hacar et al./Digitized Sky Survey 2</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Two theories for the source of water</h2>
<p>There are two potential pathways that water in our solar system could have taken. The first, called <a href="https://doi.org/10.1051/0004-6361/200810846">chemical inheritance</a>, is when the water molecules originally formed in the interstellar medium are delivered to proto-planetary disks and all the bodies they create without going through any changes. </p>
<p>The second theory is called <a href="https://doi.org/10.1051/0004-6361/201628509">chemical reset</a>. In this process, the heat from the formation of the proto-planetary disk and newborn star breaks apart water molecules, which then reform once the proto-planetary disk cools.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/515531/original/file-20230315-26-gk368.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Models of protium and deuterium." src="https://images.theconversation.com/files/515531/original/file-20230315-26-gk368.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/515531/original/file-20230315-26-gk368.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=448&fit=crop&dpr=1 600w, https://images.theconversation.com/files/515531/original/file-20230315-26-gk368.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=448&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/515531/original/file-20230315-26-gk368.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=448&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/515531/original/file-20230315-26-gk368.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=563&fit=crop&dpr=1 754w, https://images.theconversation.com/files/515531/original/file-20230315-26-gk368.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=563&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/515531/original/file-20230315-26-gk368.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=563&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Normal hydrogen, or protium, does not contain a neutron in its nucleus, while deuterium contains one neutron, making it heavier.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Hydrogen_Deuterium_Tritium_Nuclei_Schmatic-en.svg">Dirk Hünniger/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>To test these theories, astronomers like me look at the ratio between normal water and a special kind of water called semi-heavy water. Water is normally made of two hydrogen atoms and one oxygen atom. Semi-heavy water is made of one oxygen atom, one hydrogen atom and one atom of deuterium – a heavier isotope of hydrogen with an extra neutron in its nucleus. </p>
<p>The ratio of semi-heavy to normal water is a guiding light on the water trail – measuring the ratio can tell astronomers a lot about the source of water. <a href="https://doi.org/10.1051/0004-6361/202039084">Chemical models</a> and <a href="https://doi.org/10.1086/591506">experiments</a> have shown that about 1,000 times more semi-heavy water will be produced in the cold interstellar medium <a href="https://doi.org/10.1126/science.1258055">than in the conditions of a protoplanetary disk</a>. </p>
<p>This difference means that by measuring the ratio of semi-heavy to normal water in a place, astronomers can tell whether that water went through the chemical inheritance or chemical reset pathway.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/515533/original/file-20230315-1689-gn9l6v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A star surrounded by a ring of gas and dust." src="https://images.theconversation.com/files/515533/original/file-20230315-1689-gn9l6v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/515533/original/file-20230315-1689-gn9l6v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/515533/original/file-20230315-1689-gn9l6v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/515533/original/file-20230315-1689-gn9l6v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/515533/original/file-20230315-1689-gn9l6v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/515533/original/file-20230315-1689-gn9l6v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/515533/original/file-20230315-1689-gn9l6v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">V883 Orionis is a young star system with a rare star at its center that makes measuring water in the proto-planetary cloud, shown in the cutaway, possible.</span>
<span class="attribution"><a class="source" href="https://public.nrao.edu/news/water-v883-orionis/">ALMA (ESO/NAOJ/NRAO), B. Saxton (NRAO/AUI/NSF)</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Measuring water during the formation of a planet</h2>
<p>Comets have a ratio of semi-heavy to normal water almost perfectly in line with <a href="https://doi.org/10.2458/azu_uapress_9780816531240-ch037">chemical inheritance</a>, meaning the water hasn’t undergone a major chemical change since it was first created in space. Earth’s ratio sits somewhere in between the inheritance and reset ratio, making it unclear where the water came from.</p>
<p>To truly determine where the water on planets comes from, astronomers needed to find a goldilocks proto-planetary disk – one that is just the right temperature and size to allow observations of water. Doing so has <a href="https://doi.org/10.1051/0004-6361/201935994">proved to be incredibly difficult</a>. It is possible to detect semi-heavy and normal water when water is a gas; unfortunately for astronomers, the vast majority of proto-plantary disks are very cold and <a href="https://doi.org/10.1126/science.1239560">contain mostly ice</a>, and it is nearly <a href="https://doi.org/10.1051/0004-6361:20031277">impossible to measure water ratios</a> from ice at interstellar distances. </p>
<p>A breakthrough came in 2016, when my colleagues and I were studying proto-planetary disks around a rare type of young star called FU Orionis stars. Most young stars consume matter from the proto-planetary disks around them. FU Orionis stars are unique because they consume matter about 100 times faster than typical young stars and, as a result, <a href="https://doi.org/10.1146/annurev-astro-081915-023347">emit hundreds of times more energy</a>. Due to this higher energy output, the proto-planetary disks around FU Orionis stars are heated to much higher temperatures, turning ice into water vapor out to large distances from the star.</p>
<p>Using the <a href="https://public.nrao.edu/telescopes/alma/">Atacama Large Millimeter/submillimeter Array</a>, a powerful radio telescope in northern Chile, <a href="https://ui.adsabs.harvard.edu/abs/2016Natur.535..258C/abstract">we discovered</a> a large, warm proto-planetary disk around the Sunlike young star V883 Ori, about 1,300 light years from Earth in the constellation Orion.</p>
<p>V883 Ori emits 200 times more energy than the Sun, and my colleagues and I recognized that it was an ideal candidate to observe the semi-heavy to normal water ratio. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/515565/original/file-20230315-14-dfl7h6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A radio image of the disk around V883 Ori." src="https://images.theconversation.com/files/515565/original/file-20230315-14-dfl7h6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/515565/original/file-20230315-14-dfl7h6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=672&fit=crop&dpr=1 600w, https://images.theconversation.com/files/515565/original/file-20230315-14-dfl7h6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=672&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/515565/original/file-20230315-14-dfl7h6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=672&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/515565/original/file-20230315-14-dfl7h6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=844&fit=crop&dpr=1 754w, https://images.theconversation.com/files/515565/original/file-20230315-14-dfl7h6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=844&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/515565/original/file-20230315-14-dfl7h6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=844&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The proto-planetary disk around V883 Ori contains gaseous water, shown in the orange layer, allowing astronomers to measure the ratio of semi-heavy to normal water.</span>
<span class="attribution"><a class="source" href="https://public.nrao.edu/news/water-v883-orionis/#PRimage2">ALMA (ESO/NAOJ/NRAO), J. Tobin, B. Saxton (NRAO/AUI/NSF)</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Completing the water trail</h2>
<p>In 2021, the Atacama Large Millimeter/submillimeter Array took measurements of V883 Ori for six hours. The data revealed a <a href="https://doi.org/10.1038/s41586-022-05676-z">strong signature of semi-heavy and normal water</a> coming from V883 Ori’s proto-planetary disk. We measured the ratio of semi-heavy to normal water and found that the ratio was very <a href="https://doi.org/10.1051/0004-6361/202039084">similar to ratios found in comets</a> as well as the ratios found <a href="https://doi.org/10.1051/0004-6361/201322845">in younger protostar systems</a>.</p>
<p>These results fill in the gap of the water trail forging a direct link between water in the interstellar medium, protostars, proto-planetary disks and planets like Earth through the process of inheritance, not chemical reset.</p>
<p>The new results show definitively that a substantial portion of the water on Earth most likely formed billions of years ago, before the Sun had even ignited. Confirming this missing piece of water’s path through the universe offers clues to origins of water on Earth. Scientists have previously suggested that most water on Earth <a href="https://doi.org/10.1051/0004-6361/201935554">came from comets impacting the planet</a>. The fact that Earth has less semi-heavy water than comets and V883 Ori, but more than chemical reset theory would produce, means that water on Earth likely came from more than one source.</p><img src="https://counter.theconversation.com/content/201622/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>John Tobin receives funding from NASA, </span></em></p>Astronomers have long known where water is first formed in the universe and how it ends up on planets, asteroids and comets. A recent discovery has finally answered what happens in between.John Tobin, Scientist, National Radio Astronomy ObservatoryLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1993832023-02-23T13:15:36Z2023-02-23T13:15:36ZNight skies are getting 9.6% brighter every year as light pollution erases stars for everyone<figure><img src="https://images.theconversation.com/files/510410/original/file-20230215-24-phgv5z.jpg?ixlib=rb-1.1.0&rect=747%2C249%2C5060%2C1458&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">All human development, from large cities to small towns, shines light into the night sky. </span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/evobenny/38510489362/">Benny Ang/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/510596/original/file-20230216-18-s7y17h.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/510596/original/file-20230216-18-s7y17h.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/510596/original/file-20230216-18-s7y17h.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=255&fit=crop&dpr=1 600w, https://images.theconversation.com/files/510596/original/file-20230216-18-s7y17h.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=255&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/510596/original/file-20230216-18-s7y17h.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=255&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/510596/original/file-20230216-18-s7y17h.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=321&fit=crop&dpr=1 754w, https://images.theconversation.com/files/510596/original/file-20230216-18-s7y17h.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=321&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/510596/original/file-20230216-18-s7y17h.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=321&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
<span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>For most of human history, the stars blazed in an otherwise dark night sky. But starting around the Industrial Revolution, as artificial light increasingly lit cities and towns at night, the stars began to disappear.</p>
<p>We are <a href="https://scholar.google.com/citations?user=OrRLRQ4AAAAJ&hl=en&oi=ao">two</a> <a href="https://noirlab.edu/science/about/scientists-at-noirlab">astronomers</a> who depend on dark night skies to do our research. For decades, astronomers have been <a href="https://about.ifa.hawaii.edu/facility/mauna-kea-observatories/">building telescopes</a> in the <a href="https://www.smithsonianmag.com/travel/star-trekking-chile-astronomy-180955798/">darkest places</a> on Earth to <a href="https://doi.org/10.1007/s00159-010-0032-2">avoid light pollution</a>. </p>
<p>Today, most people live in cities or suburbs that <a href="https://doi.org/10.1038/457027a">needlessly shine light into the sky at night</a>, dramatically reducing the <a href="https://doi.org/10.1126/sciadv.1600377#body-ref-R3">visibility of stars</a>. Satellite data suggests that light pollution over North America and Europe has remained <a href="https://www.science.org/doi/10.1126/sciadv.1701528">constant or has slightly decreased</a> over the last decade, while <a href="https://www.mdpi.com/2072-4292/9/8/798">increasing in other parts of the world</a>, such as Africa, Asia and South America. However, satellites miss the blue light of LEDs, which are <a href="http://dx.doi.org/10.2760/759859">commonly used for outdoor lighting</a> – resulting in an underestimate of light pollution.</p>
<p>An international citizen science project called <a href="https://globeatnight.org">Globe at Night</a> aims to measure how everyday people’s view of the sky is changing.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/510429/original/file-20230215-15-f11qnb.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A number of panels showing different numbers of stars." src="https://images.theconversation.com/files/510429/original/file-20230215-15-f11qnb.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/510429/original/file-20230215-15-f11qnb.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=540&fit=crop&dpr=1 600w, https://images.theconversation.com/files/510429/original/file-20230215-15-f11qnb.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=540&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/510429/original/file-20230215-15-f11qnb.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=540&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/510429/original/file-20230215-15-f11qnb.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=679&fit=crop&dpr=1 754w, https://images.theconversation.com/files/510429/original/file-20230215-15-f11qnb.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=679&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/510429/original/file-20230215-15-f11qnb.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=679&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Globe at Night survey asks users to select which panel – each representing different levels of light pollution – best matches the sky above them.</span>
<span class="attribution"><a class="source" href="https://globeatnight.org/webapp/">The Globe at Night</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Measuring light pollution over time</h2>
<p>Relying on citizen scientists makes it much easier to take multiple measurements of the night sky over time from many different places. </p>
<p>To provide data to the project, volunteers enter the date and time, their location and local weather conditions into an <a href="https://globeatnight.org/webapp/">online reporting page</a> anytime an hour or more after sunset on certain nights each month. The page then shows eight panels, each displaying a constellation visible at that time of year – like Orion in January and February, for example. The first panel, representing a light-polluted night sky, only shows the few brightest stars. Each panel shows progressively more and fainter stars, representing darker and darker skies. The participant then matches what they see in the sky with one of the panels. </p>
<p>The Globe at Night team launched the report page as an online app in 2011, just at the beginning of widespread adoption of LEDs. In <a href="https://doi.org/10.1126/science.abq7781">the recent paper</a>, the team filtered out data points taken during twilight, when the Moon was out, when it was cloudy or when the data was unreliable for any other reason. This left around 51,000 data points, mostly taken in North America and Europe. </p>
<p>The data shows that the night sky got, on average, <a href="https://doi.org/10.1126/science.abq7781">9.6% brighter every year</a>. For many people, the night sky today is twice as bright as it was eight years ago. The brighter the sky, the fewer stars you can see.</p>
<p>If this trend continues, a <a href="https://eos.org/articles/starry-nights-are-disappearing">child born today</a> in a place where 250 stars are visible now would only be able to see 100 stars on their 18th birthday. </p>
<h2>Causes, impacts and solutions</h2>
<p>The main culprits driving increasing brightness of the night sky are urbanization and the growing use of <a href="http://dx.doi.org/10.2760/759859">LEDs for outdoor lighting</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/510413/original/file-20230215-28-33uihp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two pictures of the constellation Orion with one showing many times more stars." src="https://images.theconversation.com/files/510413/original/file-20230215-28-33uihp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/510413/original/file-20230215-28-33uihp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=440&fit=crop&dpr=1 600w, https://images.theconversation.com/files/510413/original/file-20230215-28-33uihp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=440&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/510413/original/file-20230215-28-33uihp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=440&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/510413/original/file-20230215-28-33uihp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=553&fit=crop&dpr=1 754w, https://images.theconversation.com/files/510413/original/file-20230215-28-33uihp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=553&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/510413/original/file-20230215-28-33uihp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=553&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The more light pollution there is, the fewer stars a person can see when looking at the same part of the night sky. The image on the left depicts the constellation Orion in a dark sky, while the image on the right is taken near the city of Orem, Utah, a city of about 100,000 people.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/79297308@N00/3180280752">jpstanley/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>The loss of dark skies, both from light pollution and also from <a href="https://doi.org/10.1093/mnrasl/slab030">increasing numbers of satellites orbiting Earth</a>, threatens our ability as astronomers to do <a href="https://doi.org/10.1007/s00159-021-00138-3">good science</a>. But everyday people feel this loss too, as the degradation of dark skies is also a loss of human <a href="https://www.darksky.org/light-pollution/night-sky-heritage/">cultural heritage</a>. Starry night skies have inspired artists, writers, musicians and philosophers for thousands of years. For many, a star-filled sky provides an irreplaceable sense of awe.</p>
<p>Light pollution also interferes with the daily cycle of light and dark that <a href="https://ec.europa.eu/research-and-innovation/en/horizon-magazine/light-pollution-altering-plant-and-animal-behaviour">plants and animals</a> use to regulate sleep, nourishment and reproduction. Two-thirds of the world’s key biodiversity areas are <a href="https://www.upi.com/Science_News/2019/02/11/Light-pollution-affects-most-of-the-planets-key-wildlife-areas/1451549899187">affected by light pollution</a>.</p>
<p>Individuals and their communities can make simple changes to <a href="https://www.darksky.org/light-pollution/light-pollution-solutions/">reduce light pollution</a>. The secret is using the right amount of light, in the right place and at the right time. Shielding outdoor light fixtures so they shine downward, using bulbs that emit more yellow-colored light instead of white light and putting lights on timers or motion sensors can all help reduce light pollution.</p>
<p>The next time you are far away from a major city or another source of light pollution, look up at the night sky. A view of the roughly <a href="https://www.theatlantic.com/technology/archive/2013/11/how-many-stars-are-there-in-the-sky/281641/">2,500 stars you can see with the naked eye</a> in a truly dark sky might convince you that dark skies are a resource worth saving.</p><img src="https://counter.theconversation.com/content/199383/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Chris Impey receives funding from the National Science Foundation and Epic Games.</span></em></p><p class="fine-print"><em><span>Connie Walker works for NSF's NOIRLab and the International Astronomical Union. She is a member of the American Astronomical Society's COMPASSE and on the Board of Directors for the International Dark-Sky Association.</span></em></p>With the help of thousands of citizen scientists, a new study measured exactly how much brighter night skies are getting every year.Chris Impey, University Distinguished Professor of Astronomy, University of ArizonaConnie Walker, Scientist, National Optical-Infrared Astronomy Research LaboratoryLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1966452023-02-06T13:28:46Z2023-02-06T13:28:46ZMore lunar missions means more space junk around the Moon – two scientists are building a catalog to track the trash<figure><img src="https://images.theconversation.com/files/508149/original/file-20230203-14522-mzpn5f.jpeg?ixlib=rb-1.1.0&rect=0%2C65%2C1019%2C713&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">There are more than 100 missions to the Moon planned in the coming years, including the next Artemis missions.</span> <span class="attribution"><a class="source" href="https://www.nasa.gov/image-feature/orion-gazes-at-moon-before-return-to-earth">NASA</a></span></figcaption></figure><p>Scientists and government agencies have been worried about the <a href="https://theconversation.com/if-a-satellite-falls-on-your-house-space-law-protects-you-but-there-are-no-legal-penalties-for-leaving-junk-in-orbit-160757">space junk surrounding Earth</a> for decades. But humanity’s starry ambitions are farther reaching than the space just around Earth. Ever since the 1960s with the launch of the Apollo program and the emergence of the space race between the U.S. and Soviet Union, people have been leaving trash around the Moon, too.</p>
<p>Today, experts estimate that there are a few dozen pieces of space junk like spent rocket bodies, defunct satellites and mission-related debris orbiting in cislunar space – the space between Earth and the Moon and the area around the Moon. While this isn’t yet a large amount of junk, astronomers have very little information about where these pieces of space debris are, let alone what they are and how they got there. </p>
<p><a href="https://scholar.google.com/citations?user=XCYhJqcAAAAJ&hl=en&oi=ao">I am a planetary scientist</a> and also run the <a href="http://s4.arizona.edu">Space Safety, Security and Sustainability Center</a> at the University of Arizona. As the focus of space activities turns to the Moon, with each future mission more junk will be left in cislunar space. This junk is an emerging problem that could create hazardous conditions for astronauts and spacecraft in the future. </p>
<p>My colleague <a href="https://s4.arizona.edu/person/roberto-furfaro">Roberto Furfaro</a> and I are hoping to help prevent this problem from getting out of hand. Together, we are using telescopes and existing databases on lunar missions to find, describe and track lunar space debris and <a href="https://news.arizona.edu/story/75m-effort-seeks-prevent-lunar-traffic-jams">build the world’s first catalog</a> of cislunar space objects.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/508136/original/file-20230203-12714-rcs7sf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A lunar lander from Apollo 11 lifting off from the surface of the Moon." src="https://images.theconversation.com/files/508136/original/file-20230203-12714-rcs7sf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/508136/original/file-20230203-12714-rcs7sf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=579&fit=crop&dpr=1 600w, https://images.theconversation.com/files/508136/original/file-20230203-12714-rcs7sf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=579&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/508136/original/file-20230203-12714-rcs7sf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=579&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/508136/original/file-20230203-12714-rcs7sf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=728&fit=crop&dpr=1 754w, https://images.theconversation.com/files/508136/original/file-20230203-12714-rcs7sf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=728&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/508136/original/file-20230203-12714-rcs7sf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=728&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Since the 1960s, missions like the Apollo program missions have been sending robots and people to the Moon and leaving pieces of junk behind.</span>
<span class="attribution"><a class="source" href="https://nssdc.gsfc.nasa.gov/imgcat/html/object_page/a11_h_44_6642.html">NASA</a></span>
</figcaption>
</figure>
<h2>Abandoned and potentially dangerous</h2>
<p>Historically, NASA and the U.S. military have not closely tracked space debris from the <a href="https://moon.nasa.gov/exploration/moon-missions/">many dozens of crewed and robotic missions to the Moon</a>. There is no international agency that has monitored lunar objects, either. This lack of oversight is why scientists don’t know the location or orbit of the vast majority of lunar space debris. And these objects won’t simply go away – in the near total vacuum of space, anything left in orbit around the Moon or in cislunar space will likely remain there for at least decades.</p>
<p>This lack of information about human-made objects orbiting the Moon poses many risks for lunar missions. </p>
<p>First is the risk of collision. Humanity is at the beginning of a new wave of lunar exploration. Over the next 10 years, six countries and several commercial companies have plans for <a href="https://www.jhuapl.edu/NewsStory/221205-apl-cislunar-traffic-management">more than 100 missions</a>. With every mission, the risk of a collision with existing debris increases and so, too, does the total amount of debris as missions leave junk behind. </p>
<p>Crash landings onto the surface of the Moon are also a real risk because the Moon does not have a thick atmosphere that can burn up falling space junk. This was dramatically demonstrated by the impact of a <a href="https://theconversation.com/a-rocket-crashes-into-the-moon-the-accidental-experiment-will-shed-light-on-the-physics-of-impacts-in-space-177977">spent Chinese rocket booster</a> into the far side of the Moon in March 2022. My team and I were the ones to <a href="https://news.engineering.arizona.edu/news/ua-students-confirm-errant-rockets-chinese-origin-track-lunar-collision-course">finally identify that object as being of Chinese origin</a> using telescopes we built to track objects in cislunar space. With both the U.S. and China planning to build lunar bases in the coming years, falling debris could become a real threat to human life and infrastructure on the Moon.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A video taken by NASA’s Juno spacecraft shows just how far away the Moon is from Earth.</span></figcaption>
</figure>
<h2>Hard to track</h2>
<p>If you want to prevent the Moon from becoming a cosmic landfill, you need to be able to track cislunar space junk. But doing so is challenging even on a good day for two main reasons: distance and light.</p>
<p>Cislunar space extends about 2.66 million miles from Earth – far past the distance within which the U.S. government <a href="https://www.jtf-spacedefense.mil/About-Us/Fact-Sheets/Display/Article/3155799/18th-space-defense-squadron/">currently tracks objects in space</a>. But space is not just two-dimensional. The <a href="https://www.afrl.af.mil/Portals/90/Documents/RV/A%20Primer%20on%20Cislunar%20Space_Dist%20A_PA2021-1271.pdf?ver=vs6e0sE4PuJ51QC-15DEfg%3D%3D">three-dimensional volume of cislunar space is massive,</a> and any objects within it are tiny by comparison.</p>
<p>Light presents another challenge. Just like the Moon itself, the brightness of an object in cislunar space depends on how much sunlight the object reflects. During a crescent moon, lunar debris appears dim and low in the evening sky, making it hard to find. During a full moon, the same objects are high in the sky and brighter due to more sunlight hitting them, but they blend in with the <a href="https://www.sciencedirect.com/topics/chemistry/rayleigh-scattering">bright glare that surrounds a full moon</a>. Spotting objects during a full moon is like trying to find a firefly’s faint glow next to a bright search light. Within the lunar glare is the <a href="https://amostech.com/TechnicalPapers/2021/Cislunar-SSA/Furfaro.pdf">Cone of Shame</a>, so named because of the difficulty in tracking objects within it.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/508150/original/file-20230203-7549-e3xoli.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A large, black telescope." src="https://images.theconversation.com/files/508150/original/file-20230203-7549-e3xoli.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/508150/original/file-20230203-7549-e3xoli.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=794&fit=crop&dpr=1 600w, https://images.theconversation.com/files/508150/original/file-20230203-7549-e3xoli.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=794&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/508150/original/file-20230203-7549-e3xoli.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=794&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/508150/original/file-20230203-7549-e3xoli.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=997&fit=crop&dpr=1 754w, https://images.theconversation.com/files/508150/original/file-20230203-7549-e3xoli.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=997&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/508150/original/file-20230203-7549-e3xoli.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=997&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A team of students and professors at the University of Arizona built a telescope to track objects near the Moon.</span>
<span class="attribution"><span class="source">Vishnu Reddy/University of Arizona</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Curating the catalog</h2>
<p>Because of the difficulty and lack of adequate resources to track objects near the Moon, there is no group or organization consistently doing so today. So, in 2020, Furfaro and I took on the challenge to discover, track and<a href="https://news.arizona.edu/story/75m-effort-seeks-prevent-lunar-traffic-jams"> catalog human-made debris in cislunar space</a>. </p>
<p>First, we linked historical observations from various telescopes and databases to each other to identify and confirm what cislunar objects were already known. Then, realizing there were no dedicated telescopes scanning the night sky for cislunar objects, my students at the University of Arizona and I built one. In late 2020, we finished building a 24-inch-diameter (0.6-meter-diameter) telescope, which is at the <a href="https://biosphere2.org/about/about-biosphere-2">Biosphere 2 Observatory</a> near Tucson. </p>
<p>The first object we tracked was Chang’e 5, China’s first lunar sample return mission. The large rocket launched on Nov. 23, 2020, headed toward the Moon. Despite the powerful lunar glare, my students and I were able to track <a href="https://amostech.com/TechnicalPapers/2021/Cislunar-SSA/Furfaro.pdf">Chang’e 5</a> to a distance of 12,354 miles from the Moon, deep into the Cone of Shame. With this success, we started tracking newly launched cislunar payloads and adding them to our nascent catalog. With this success, we started tracking newly launched cislunar payloads so we can calculate and predict their orbits to prevent them from getting lost.</p>
<p>To characterize both old and new space debris, once we figure out where an object is, we use <a href="https://amostech.com/TechnicalPapers/2021/Non-Resolved-Object-Characterization/Reddy.pdf">optical and near-infrared telescopes on Earth</a> to capture the object’s spectral signature – the specific wavelengths of light that bounce off an object’s surface. By doing this, we can figure out what material an object is made out of and identify it. This is how we identified the <a href="https://theconversation.com/a-rocket-crashes-into-the-moon-the-accidental-experiment-will-shed-light-on-the-physics-of-impacts-in-space-177977">mystery rocket booster that crashed into the Moon</a> in 2022. We can also measure changes in the light bouncing off the object over time to determine how fast that object is spinning, which can also help with identification.</p>
<p>Over the last two years, we have become better and better at finding and identifying objects in cislunar space. While at first we were happy to identify the school bus-sized Chang’e 5 spacecraft, now we are able to track CubeSats no bigger than a cereal box – like <a href="https://www.jpl.nasa.gov/images/pia25257-nasas-lunar-flashlight-spotted-from-earth-on-its-way-to-the-moon">NASA’s Lunar Flashlight</a>.</p>
<p>To date, my team has been able to identify a few dozen pieces of debris in cislunar space and are continuing to add to our ever-expanding catalog. The vast majority of the work ahead comprises continued observations and matching objects to known missions to confirm what objects are out there and where they came from.</p>
<p>While there is still a long way to go, these efforts are designed to ultimately form the basis for a catalog that will help lead to safer, more sustainable use of cislunar orbital space as humanity begins its expansion off of the Earth.</p><img src="https://counter.theconversation.com/content/196645/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Vishnu Reddy is employed as a faculty member at The University of Arizona.
He has received grant funding from NASA and the US Air Force/DoD.</span></em></p>With more than 100 lunar missions planned in coming years, space junk near the Moon could become an issue for humanity. No agency tracks lunar space junk, so two astronomers decided to do it themselves.Vishnu Reddy, Professor of Planetary Science, University of ArizonaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1868002022-07-13T00:01:03Z2022-07-13T00:01:03ZJames Webb Space Telescope: An astronomer explains the stunning, newly released first images<figure><img src="https://images.theconversation.com/files/473703/original/file-20220712-12-aekfeq.png?ixlib=rb-1.1.0&rect=0%2C134%2C1880%2C1368&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">This cluster of galaxies, called Stephan's Quintet, is a composite image produced from two cameras aboard the James Webb Space Telescope.</span> <span class="attribution"><a class="source" href="https://webbtelescope.org/contents/media/images/2022/034/01G7DA5ADA2WDSK1JJPQ0PTG4A?news=true">NASA/STScI</a></span></figcaption></figure><p>The James Webb Space Telescope team has <a href="https://www.nasa.gov/webbfirstimages">released the first science-quality images</a> from the new telescope. In them are the oldest galaxies ever seen by human eyes, evidence of water on a planet 1,000 light-years away and incredible details showing the birth and death of stars. Webb’s purpose is to explore origins – of the universe, of galaxies, of stars and of life – and the five images released on July 12, 2022, make good on that promise. </p>
<p>Once the suite of instruments onboard all <a href="https://theconversation.com/the-james-webb-space-telescope-is-finally-ready-to-do-science-and-its-seeing-the-universe-more-clearly-than-even-its-own-engineers-hoped-for-184989">cooled down and were running smoothly</a>, astronomers wasted no time in putting Webb to work. Each of the first images contains enough data to produce major scientific results on their own. </p>
<p>Webb was designed to <a href="https://theconversation.com/the-most-powerful-space-telescope-ever-built-will-look-back-in-time-to-the-dark-ages-of-the-universe-169603">collect light across the entire red to mid-infrared spectrum</a> – wavelengths of light that are blocked by Earth’s atmosphere. And with its giant mirror and sun-shade blocking infrared emitted by the Sun, Earth and Moon, Webb can produce images of a sharpness never before achieved by any other telescope. </p>
<p>The buzz among <a href="https://www.uml.edu/Sciences/physics/faculty/Laycock-Silas.aspx">professional astronomers like me</a> has been electric since members of the Webb team shared tantalizing test images. And the real images are even better than anyone could have hoped for. During the presentation where the first images were released, Webb <a href="https://www.nasa.gov/content/first-images-from-the-james-webb-space-telescope">project scientist Jane Rigby remarked</a> “for Webb there is no blank sky, everywhere it looks it sees distant galaxies.” Most of those galaxies were invisible until now.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/473704/original/file-20220712-12-qk9b76.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photo showing thousands of galaxies in a night sky." src="https://images.theconversation.com/files/473704/original/file-20220712-12-qk9b76.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/473704/original/file-20220712-12-qk9b76.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=612&fit=crop&dpr=1 600w, https://images.theconversation.com/files/473704/original/file-20220712-12-qk9b76.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=612&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/473704/original/file-20220712-12-qk9b76.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=612&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/473704/original/file-20220712-12-qk9b76.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=769&fit=crop&dpr=1 754w, https://images.theconversation.com/files/473704/original/file-20220712-12-qk9b76.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=769&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/473704/original/file-20220712-12-qk9b76.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=769&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This photo shows gravitational lensing and many bright galaxies, but the smaller, fainter, less distinct galaxies in this image are some of the oldest light ever detected by a human-made object.</span>
<span class="attribution"><a class="source" href="https://webbtelescope.org/contents/media/images/2022/035/01G7DCWB7137MYJ05CSH1Q5Z1Z?news=true">NASA/STScI</a></span>
</figcaption>
</figure>
<h2>Ancient galaxies and the early universe</h2>
<p>The first Webb image the world saw is of a galaxy cluster known to astronomers as <a href="https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-delivers-deepest-infrared-image-of-universe-yet">SMACS 0723</a>. It lies in the southern hemisphere sky and is 5.12 billion light-years from Earth. </p>
<p>The detail of the thousands of individual galaxies in the image is stunning. It is like the universe in high definition, and I encourage you to look at the <a href="https://stsci-opo.org/STScI-01G7JJADTH90FR98AKKJFKSS0B.png">full resolution image</a> and zoom in to truly appreciate the details. </p>
<p>The large white galaxies in the middle of the image belong to the cluster and are similar in age to the Sun and Earth. Surrounding and interspersed among the cluster galaxies are more distant galaxies, but stretched into spectacular arcs as if seen through a magnifying glass. And that is exactly what is happening. The background galaxies are much farther from Earth but appear magnified, as their light is bent toward Earth by the gravity of the much closer cluster. </p>
<p>In the background you can see faint red galaxies scattered like rubies across the sky. Those galaxies are even farther away. By measuring precise attributes of their light, astronomers can tell that they formed over 13 billion years ago and even determine the abundance of different elements in these early galaxies. </p>
<p>Webb is not only producing incredibly sharp images, but it is doing so easily when compared to its predecessor, the Hubble Space Telescope, which was launched in 1990. As Rigby quipped, “… the Hubble Extremely Deep Field took two weeks of exposure, Webb went deeper before breakfast.” Once Webb carries out longer observations that allow it to collect more light from faint stars or galaxies, astronomers will be able to see some of the first stars and galaxies that formed right after the Big Bang. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/473706/original/file-20220712-9214-uyqbas.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A chart showing peaks and valleys of light at different wavelengths." src="https://images.theconversation.com/files/473706/original/file-20220712-9214-uyqbas.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/473706/original/file-20220712-9214-uyqbas.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/473706/original/file-20220712-9214-uyqbas.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/473706/original/file-20220712-9214-uyqbas.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/473706/original/file-20220712-9214-uyqbas.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/473706/original/file-20220712-9214-uyqbas.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/473706/original/file-20220712-9214-uyqbas.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The James Webb Space Telescope is sensitive enough to not only detect light that passes though the atmospheres of distant planets, but to measure the strength of this light at different wavelengths – as shown here – which can suggest the presence of water or other molecules in an atmosphere.</span>
<span class="attribution"><a class="source" href="https://webbtelescope.org/contents/media/images/2022/032/01G72VSFW756JW5SXWV1HYMQK4?news=true">NASA/STScI</a></span>
</figcaption>
</figure>
<h2>Understanding planets around other stars</h2>
<p>The second reveal was not of an image but a spectrum – a breakdown of the strength of light at different wavelengths. </p>
<p>Webb pointed its mirror at the <a href="https://theconversation.com/accelerating-exoplanet-discovery-using-chemical-signatures-of-stars-118818">exoplanet</a> WASP 96-B – a giant hot gas planet orbiting a star about 1,000 light-years from Earth – as the planet passed in front of its parent star. During this transit, a portion of the star’s light was filtered through the planet’s atmosphere and left a “chemical fingerprint” in the light’s unique spectrum. The specifics of this fingerprint strongly suggest that there is water vapor, clouds and haze in the atmosphere of WASP 96-B. </p>
<p>As Webb moves on to observe <a href="https://theconversation.com/an-earth-sized-planet-found-in-the-habitable-zone-of-a-nearby-star-129290">smaller planets that could potentially harbor life</a>, astronomers expect to detect the fingerprints of oxygen, nitrogen, ammonia and carbon in the form of methane and other hydrocarbons. The goal is to find biosignatures of life – that is, chemistry that would point toward the atmosphere being modified by living organisms. </p>
<p>The technical challenge of doing this type of observation, called transit spectroscopy, is enormous, and this initial result barely scratches the surface of the scientific content of the spectrum.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/473711/original/file-20220712-31570-vot4hk.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A giant hazy cloud of gas and dust with points of light within." src="https://images.theconversation.com/files/473711/original/file-20220712-31570-vot4hk.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/473711/original/file-20220712-31570-vot4hk.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=348&fit=crop&dpr=1 600w, https://images.theconversation.com/files/473711/original/file-20220712-31570-vot4hk.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=348&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/473711/original/file-20220712-31570-vot4hk.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=348&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/473711/original/file-20220712-31570-vot4hk.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=437&fit=crop&dpr=1 754w, https://images.theconversation.com/files/473711/original/file-20220712-31570-vot4hk.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=437&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/473711/original/file-20220712-31570-vot4hk.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=437&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Fine details seen in this image of the Carina Nebula offer clues to how stars are born.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-reveals-cosmic-cliffs-glittering-landscape-of-star-birth">NASA/STScI</a></span>
</figcaption>
</figure>
<h2>Galactic dances and the lives of stars</h2>
<p>The last three images showed the incredible resolution of Webb’s optics as the telescope explored the birth and death of stars. </p>
<p>Webb’s ability to capture light in the mid-infrared range allows its cameras to cut through dense clouds of dust and gas. This ability helped Webb to capture <a href="https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-reveals-cosmic-cliffs-glittering-landscape-of-star-birth">spectacular details of the Carina Nebula</a> where stars are born.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/473705/original/file-20220712-26-cqe66p.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two side-by-side images of a round cloud of gas around a bright star." src="https://images.theconversation.com/files/473705/original/file-20220712-26-cqe66p.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/473705/original/file-20220712-26-cqe66p.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=278&fit=crop&dpr=1 600w, https://images.theconversation.com/files/473705/original/file-20220712-26-cqe66p.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=278&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/473705/original/file-20220712-26-cqe66p.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=278&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/473705/original/file-20220712-26-cqe66p.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=350&fit=crop&dpr=1 754w, https://images.theconversation.com/files/473705/original/file-20220712-26-cqe66p.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=350&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/473705/original/file-20220712-26-cqe66p.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=350&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Webb telescope can take high resolution images using multiple cameras with each revealing different details, as demonstrated in these side-by-side photos of a dying star.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-captures-dying-star-s-final-performance-in-fine-detail">NASA/STScI</a></span>
</figcaption>
</figure>
<p>Webb is also excellently suited to study the end of a star’s life. As stars get old, they can puff off their outer layers and form nebulas like the stunning <a href="https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-captures-dying-star-s-final-performance-in-fine-detail">Southern Ring Nebula, which was imaged by Webb</a>. The image revealed never-before-seen details of successive waves of matter expelled by the dying central star. While Hubble was unable to see through the expanding cloud of dust and debris, Webb provided the first look at the binary star system that formed the nebula.</p>
<p>The last photo from Webb’s coming out party <a href="https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-sheds-light-on-galaxy-evolution-black-holes">showed Stephan’s Quintet</a>, a group of five galaxies 300 million light-years from Earth, interacting in a cosmic dance. Thanks to the suite of complementary instruments aboard Webb, the telescope can simultaneously pick up details of individual stars in these galaxies, see the cold dust and gas fueling star formation within these galaxies and – most remarkably – block out the stars, gas and dust to see the material swirling around the supermassive black hole at the center of one of the galaxies. </p>
<p>Webb also captured data on the spectra of hundreds of individual star-forming regions in the Quintet, which will take months to analyze and study.</p>
<p>Webb is the result of 25 years of work by thousands of scientists, engineers and administrators belonging to an international collaboration of space agencies, companies, research centers and universities worldwide. John Mather, a project leader for Webb, <a href="https://www.nasa.gov/content/first-images-from-the-james-webb-space-telescope">emotionally described the journey</a>: “This was hard to do. It is difficult to express just how hard this was. There were so many thousands of ways it could have gone wrong.”</p>
<p>But it didn’t go wrong. It all came together, and now humanity’s greatest space telescope is open for business.</p>
<p><em>This story was updated to correct the description of the photo of the Southern Ring Nebula.</em></p><img src="https://counter.theconversation.com/content/186800/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Silas Laycock works at The University of Massachusetts Lowell. He receives funding from NASA and the NSF. He is affiliated with the American Astronomical Society, and the Lowell Center for Space Science and Technology.</span></em></p>NASA released five new images from the James Webb Space Telescope, revealing incredible details of ancient galaxies, stars and the presence of water in the atmosphere of a distant planet.Silas Laycock, Professor of Astronomy, UMass LowellLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1849892022-06-15T12:26:32Z2022-06-15T12:26:32ZThe James Webb Space Telescope is finally ready to do science – and it’s seeing the universe more clearly than even its own engineers hoped for<figure><img src="https://images.theconversation.com/files/468846/original/file-20220614-21-gxm00d.jpg?ixlib=rb-1.1.0&rect=170%2C463%2C4769%2C2962&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The mirror on the James Webb Space Telescope is fully aligned and producing incredibly sharp images, like this test image of a star.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/nasawebbtelescope/51942047253/">NASA/STScI via Flickr</a></span></figcaption></figure><p><em>NASA is scheduled to release the first images taken by the James Webb Space Telescope on July 12, 2022. They’ll mark the beginning of the next era in astronomy as Webb – the largest space telescope ever built – begins collecting scientific data that will help answer questions about the earliest moments of the universe and allow astronomers to study exoplanets in greater detail than ever before. But it has taken nearly eight months of travel, setup, testing and calibration to make sure this most valuable of telescopes is ready for prime time. <a href="https://scholar.google.com/citations?user=WajSxxMAAAAJ&hl=en&oi=ao">Marcia Rieke, an astronomer at the University of Arizona</a> and the scientist in charge of one of Webb’s four cameras, explains what she and her colleagues have been doing to get this telescope up and running.</em> </p>
<h2>1. What’s happened since the telescope launched?</h2>
<p>After the successful launch of the James Webb Space Telescope on Dec. 25, 2021, the team began the long process of moving the telescope into its final orbital position, unfolding the telescope and – as everything cooled – calibrating the cameras and sensors onboard. </p>
<p>The launch went as smoothly as a rocket launch can go. One of the first things my colleagues at NASA noticed was that the telescope had more remaining fuel onboard than predicted to make future adjustments to its orbit. This will allow Webb to <a href="https://blogs.nasa.gov/webb/2021/12/29/nasa-says-webbs-excess-fuel-likely-to-extend-its-lifetime-expectations/">operate for much longer</a> than the mission’s initial 10-year goal.</p>
<p>The first task during Webb’s monthlong journey to its final location in orbit was to unfold the telescope. This went along without any hitches, starting with the <a href="https://www.nasa.gov/press-release/sunshield-successfully-deploys-on-nasa-s-next-flagship-telescope">white-knuckle deployment of the sun shield</a> that helps cool the telescope, followed by the alignment of the mirrors and the turning on of sensors.</p>
<p>Once the sun shield was open, our team began monitoring the temperatures of the <a href="https://theconversation.com/james-webb-space-telescope-an-astronomer-on-the-team-explains-how-to-send-a-giant-telescope-to-space-and-why-167516">four cameras and spectrometers onboard</a>, waiting for them to reach temperatures low enough so that we could start testing each of the <a href="https://blogs.nasa.gov/webb/2022/05/12/seventeen-modes-to-discovery-webbs-final-commissioning-activities/">17 different modes in which the instruments can operate</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/468847/original/file-20220614-12-bdzy11.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A gold-plated complicated piece of technology sitting on a table." src="https://images.theconversation.com/files/468847/original/file-20220614-12-bdzy11.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/468847/original/file-20220614-12-bdzy11.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=396&fit=crop&dpr=1 600w, https://images.theconversation.com/files/468847/original/file-20220614-12-bdzy11.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=396&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/468847/original/file-20220614-12-bdzy11.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=396&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/468847/original/file-20220614-12-bdzy11.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=497&fit=crop&dpr=1 754w, https://images.theconversation.com/files/468847/original/file-20220614-12-bdzy11.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=497&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/468847/original/file-20220614-12-bdzy11.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=497&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The NIRCam on Webb was the first instrument to go online and helped align the 18 mirror segments.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:JWST_Nircam1lwres.jpg#/media/File:JWST_Nircam1lwres.jpg">NASA Goddard Space Center/Wikimedia Commons</a></span>
</figcaption>
</figure>
<h2>2. What did you test first?</h2>
<p>The cameras on Webb cooled just as the engineers predicted, and the first instrument the team turned on was the Near Infrared Camera – or NIRCam. NIRCam is designed to study the <a href="https://www.jwst.nasa.gov/content/observatory/instruments/nircam.html">faint infrared light produced by the oldest stars or galaxies</a> in the universe. But before it could do that, NIRCam had to help align the 18 individual segments of Webb’s mirror.</p>
<p>Once NIRCam cooled to minus 280 F, it was cold enough to start detecting light reflecting off of Webb’s mirror segments and produce the telescope’s first images. The NIRCam team was ecstatic when the first light image arrived. We were in business! </p>
<p>These images showed that the mirror segments were <a href="https://blogs.nasa.gov/webb/2022/02/11/photons-received-webb-sees-its-first-star-18-times/">all pointing at a relatively small area of the sky</a>, and the alignment was much better than the worst-case scenarios we had planned for.</p>
<p>Webb’s Fine Guidance Sensor also went into operation at this time. This sensor helps keep the telescope pointing steadily at a target – much like image stabilization in consumer digital cameras. Using the star HD84800 as a reference point, my colleagues on the NIRCam team helped dial in the alignment of the mirror segments until it was virtually perfect, <a href="https://www.nasa.gov/press-release/nasa-s-webb-reaches-alignment-milestone-optics-working-successfully">far better than the minimum required for a successful mission</a>.</p>
<h2>3. What sensors came alive next?</h2>
<p>As the mirror alignment wrapped up on March 11, the Near Infrared Spectrograph – NIRSpec – and the Near Infrared Imager and Slitless Spectrograph – NIRISS – finished cooling and joined the party.</p>
<p>NIRSpec is designed to measure the <a href="https://jwst.nasa.gov/content/observatory/instruments/nirspec.html">strength of different wavelengths of light</a> coming from a target. This information can reveal the composition and temperature of distant stars and galaxies. NIRSpec does this by looking at its target object through a slit that keeps other light out. </p>
<p>NIRSpec has multiple slits that allow it to <a href="https://jwst-docs.stsci.edu/jwst-near-infrared-spectrograph/nirspec-instrumentation/nirspec-fixed-slits">look at 100 objects at once</a>. Team members began by testing the multiple targets mode, commanding the slits to open and close, and they confirmed that the slits were responding correctly to commands. Future steps will measure exactly where the slits are pointing and check that <a href="https://www.stsci.edu/jwst/instrumentation/instruments#section-8bc155d1-1325-4c34-b2c0-c1bb6524cdbd">multiple targets can be observed simultaneously</a>. </p>
<p>NIRISS is a slitless spectrograph that will also break light into its different wavelengths, but it is better at <a href="https://blogs.nasa.gov/webb/2022/06/03/the-modes-of-webbs-niriss/">observing all the objects in a field, not just ones on slits</a>. It has several modes, including two that are designed specifically for studying exoplanets particularly close to their parent stars.</p>
<p>So far, the instrument checks and calibrations have been proceeding smoothly, and the results show that both NIRSpec and NIRISS will deliver even better data than engineers predicted before launch.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/468848/original/file-20220614-17290-p0op1u.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two images showing a tangled web of stars and dust but the one on the right is much sharper." src="https://images.theconversation.com/files/468848/original/file-20220614-17290-p0op1u.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/468848/original/file-20220614-17290-p0op1u.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=458&fit=crop&dpr=1 600w, https://images.theconversation.com/files/468848/original/file-20220614-17290-p0op1u.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=458&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/468848/original/file-20220614-17290-p0op1u.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=458&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/468848/original/file-20220614-17290-p0op1u.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=575&fit=crop&dpr=1 754w, https://images.theconversation.com/files/468848/original/file-20220614-17290-p0op1u.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=575&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/468848/original/file-20220614-17290-p0op1u.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=575&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The MIRI camera, image on the right, allows astronomers to see through dust clouds with incredible sharpness compared with previous telescopes like the the Spitzer Space Telescope, which produced the image on the left.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/nasawebbtelescope/52061788279/in/album-72177720296737701/">NASA/JPL-Caltech (left), NASA/ESA/CSA/STScI (right)/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>4. What was the last instrument to turn on?</h2>
<p>The final instrument to boot up on Webb was the Mid-Infrared Instrument, or MIRI. MIRI is designed to take photos of distant or newly formed galaxies as well as faint, small objects like asteroids. This sensor detects the longest wavelengths of Webb’s instruments and must be kept at minus 449 F – just 11 degrees F above absolute zero. If it were any warmer, the detectors would pick up only the heat from the instrument itself, not the interesting objects out in space. MIRI has <a href="https://jwst.nasa.gov/content/about/innovations/cryocooler.html">its own cooling system</a>, which needed extra time to become fully operational before the instrument could be turned on.</p>
<p>Radio astronomers have found hints that there are galaxies completely <a href="http://www.sci-news.com/astronomy/alma-dust-obscured-galaxies-early-universe-10094.html">hidden by dust and undetectable by telescopes like Hubble</a> that captures wavelengths of light similar to those visible to the human eye. The extremely cold temperatures allow MIRI to be incredibly sensitive to light in the mid-infrared range which can pass through dust more easily. When this sensitivity is combined with Webb’s large mirror, it allows MIRI to <a href="https://blogs.nasa.gov/webb/2022/05/09/miris-sharper-view-hints-at-new-possibilities-for-science/">penetrate these dust clouds and reveal the stars and structures</a> in such galaxies for the first time. </p>
<h2>5. What’s next for Webb?</h2>
<p>As of June 15, 2022, all of Webb’s instruments are on and have taken their first images. Additionally, four imaging modes, three time series modes and three spectroscopic modes have been tested and certified, leaving just three to go.</p>
<p>On July 12, NASA plans to <a href="https://www.nasa.gov/feature/goddard/2022/first-images-from-nasa-s-webb-space-telescope-coming-soon">release a suite of teaser observations</a> that illustrate Webb’s capabilities. These will show the beauty of Webb imagery and also give astronomers a real taste of the quality of data they will receive.</p>
<p>After July 12, the James Webb Space Telescope will start working full time on its science mission. The detailed schedule for the coming year hasn’t yet been released, but astronomers across the world are eagerly waiting to get the first data back from the most powerful space telescope ever built.</p><img src="https://counter.theconversation.com/content/184989/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Marcia Rieke receives funding from NASA.</span></em></p>It has taken eight months to test and calibrate all of the instruments and modes of the James Webb Space Telescope. A scientist on the team explains what it took to get Webb up and running.Marcia Rieke, Regents Professor of Astronomy, University of ArizonaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1820362022-04-29T12:25:25Z2022-04-29T12:25:25ZBlasting out Earth’s location with the hope of reaching aliens is a controversial idea – two teams of scientists are doing it anyway<figure><img src="https://images.theconversation.com/files/460137/original/file-20220427-22-fkbhja.jpg?ixlib=rb-1.1.0&rect=377%2C0%2C3616%2C1209&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Scientists think there are 300 million habitable planets in the Milky Way, and some may be home to intelligent life.</span> <span class="attribution"><a class="source" href="http://www.eso.org/public/images/milkyway/">Bruno Gilli/ESO</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>If a person is lost in the wilderness, they have two options. They can search for civilization, or they could make themselves easy to spot by building a fire or writing HELP in big letters. For scientists interested in the question of whether intelligent aliens exist, the options are much the same.</p>
<hr>
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<p>For over 70 years, astronomers have been scanning for radio or optical signals from other civilizations in the search for extraterrestrial intelligence, called <a href="https://www.seti.org/">SETI</a>. Most scientists are confident that life exists on many of the <a href="https://www.nasa.gov/feature/ames/kepler-occurrence-rate">300 million potentially habitable worlds</a> in the Milky Way galaxy. Astronomers also think there is a <a href="https://www.scientificamerican.com/article/how-many-aliens-are-in-the-milky-way-astronomers-turn-to-statistics-for-answers/">decent chance some life forms have developed intelligence and technology</a>. But no signals from another civilization have ever been detected, a mystery that is called “<a href="https://earthsky.org/space/meti-workshop-in-paris-fermis-paradox-great-silence/">The Great Silence</a>.” </p>
<p>While SETI has long been a part of mainstream science, <a href="http://meti.org/">METI</a>, or messaging extraterrestrial intelligence, has been less common.</p>
<p>I’m a <a href="https://scholar.google.com/citations?user=OrRLRQ4AAAAJ&hl=en">professor of astronomy</a> who has written extensively about the search for life in the universe. I also serve on the advisory council for a nonprofit research organization that’s <a href="http://meti.org/en/advisors">designing messages to send to extraterrestrial civilizations</a>.</p>
<p>In the coming months, two teams of astronomers are going to send messages into space in an attempt to <a href="https://www.universetoday.com/155061/astronomers-come-up-with-a-new-message-to-let-the-aliens-know-were-here/">communicate with any intelligent aliens</a> who may be out there listening.</p>
<p>These efforts are like building a big bonfire in the woods and hoping someone finds you. But some people question whether it is wise to do this at all.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/460140/original/file-20220427-24-lnf43y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A gold plaque with the shape of a man and a woman and some lines depicting the solar system." src="https://images.theconversation.com/files/460140/original/file-20220427-24-lnf43y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/460140/original/file-20220427-24-lnf43y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=472&fit=crop&dpr=1 600w, https://images.theconversation.com/files/460140/original/file-20220427-24-lnf43y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=472&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/460140/original/file-20220427-24-lnf43y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=472&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/460140/original/file-20220427-24-lnf43y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=593&fit=crop&dpr=1 754w, https://images.theconversation.com/files/460140/original/file-20220427-24-lnf43y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=593&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/460140/original/file-20220427-24-lnf43y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=593&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Pioneer 10 spacecraft carries this plaque, which describes some basic information about humans and the Earth.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Pioneer10-plaque_tilt.jpg#/media/File:Pioneer10-plaque_tilt.jpg">Carl Sagan, Frank Drake, Linda Salzman Sagan, NASA Ames Research Center via WikimediaCommons</a></span>
</figcaption>
</figure>
<h2>The history of METI</h2>
<p>Early attempts to contact life off Earth were quixotic messages in a bottle. </p>
<p>In 1972, NASA launched the Pioneer 10 spacecraft toward Jupiter carrying a <a href="https://www.planetary.org/articles/0120-the-pioneer-plaque-science-as-a-universal-language">plaque with a line drawing of a man and a woman</a> and symbols to show where the craft originated. In 1977, NASA followed this up with the famous <a href="https://voyager.jpl.nasa.gov/golden-record/">Golden Record</a> attached to the <a href="https://theconversation.com/voyager-golden-records-40-years-later-real-audience-was-always-here-on-earth-79886">Voyager 1 spacecraft</a>.</p>
<p>These spacecraft – as well as their twins, Pioneer 11 and Voyager 2 – have now all <a href="https://www.space.com/43158-what-spacecraft-will-enter-interstellar-space-next.html">travelled well past the orbits of the outer planets</a>. But in the immensity of space, the odds that these or any other physical objects will be found are fantastically minuscule. </p>
<p>Electromagnetic radiation is a much more effective beacon.</p>
<p>Astronomers beamed the first radio message designed for alien ears from the <a href="https://www.naic.edu/ao/landing">Arecibo Observatory</a> in Puerto Rico in 1974. The <a href="http://www.naic.edu/challenge/about-message.html">series of 1s and 0s</a> was designed to convey simple information about humanity and biology and was sent toward the globular cluster M13. Since M13 is 25,000 light-years away, you shouldn’t hold your breath for a reply.</p>
<p>In addition to these purposeful attempts at sending a message to aliens, wayward signals from television and radio broadcasts have been leaking into space for nearly a century. This ever-expanding bubble of earthly babble has already reached millions of stars. But there is a big difference between a focused blast of radio waves from a giant telescope and diffuse leakage – the weak <a href="https://www.npr.org/sections/krulwich/2011/08/05/89700174/lucys-laugh-enlivens-the-solar-system">signal from a show like “I Love Lucy”</a> fades below the hum of radiation left over from the Big Bang soon after it leaves the solar system.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/460135/original/file-20220427-17-yuvu1q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A giant spherical dish-shaped telescope on the top of a mountain." src="https://images.theconversation.com/files/460135/original/file-20220427-17-yuvu1q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/460135/original/file-20220427-17-yuvu1q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/460135/original/file-20220427-17-yuvu1q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/460135/original/file-20220427-17-yuvu1q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/460135/original/file-20220427-17-yuvu1q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/460135/original/file-20220427-17-yuvu1q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/460135/original/file-20220427-17-yuvu1q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The new FAST telescope in China is the largest radio telescope ever built and will be used to send a message toward the center of the galaxy.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/march-31-2021-aerial-photo-taken-on-march-31-2021-shows-news-photo/1232035199?adppopup=true">Ou Dongqu/Xinhua via Getty Images</a></span>
</figcaption>
</figure>
<h2>Sending new messages</h2>
<p>Nearly half a century after the Arecibo message, two international teams of astronomers are planning new attempts at alien communication. One is using a giant new radio telescope, and the other is choosing a compelling new target.</p>
<p>One of these new messages will be sent from the <a href="https://fast.bao.ac.cn/">world’s largest radio telescope</a>, in China, sometime in 2023. The telescope, with a 1,640-foot (500-meter) diameter, will beam a series of radio pulses over a broad swath of sky. These on-off pulses are like the 1s and 0s of digital information. </p>
<p>The message is called “<a href="https://arxiv.org/abs/2203.04288">The Beacon in the Galaxy</a>” and includes prime numbers and mathematical operators, the biochemistry of life, human forms, the Earth’s location and a time stamp. The team is sending the message toward a group of millions of stars near the center of the Milky Way galaxy, about 10,000 to 20,000 light-years from Earth. While this maximizes the pool of potential aliens, it means it will be tens of thousands of years before Earth may get a reply.</p>
<p>The other attempt is targeting only a single star, but with the potential for a much quicker reply. On Oct. 4, 2022, a team from the Goonhilly Satellite Earth Station in England will beam a message toward the star <a href="https://www.newscientist.com/article/2315676-group-that-wants-to-contact-aliens-will-transmit-to-trappist-1-system/">TRAPPIST-1</a>. This star has seven planets, three of which <a href="https://theconversation.com/ultracool-dwarf-star-hosts-three-potentially-habitable-earth-sized-planets-just-40-light-years-away-58695">are Earth-like worlds in the so-called “Goldilocks zone</a>” – meaning they could be home to liquid and potentially life, too. TRAPPIST-1 is just 39 light-years away, so it could take as few as 78 years for intelligent life to receive the message and Earth to get the reply.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/460136/original/file-20220427-16-5v9rcq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An image of a dense, bulbous, gas- and star-filled region of space." src="https://images.theconversation.com/files/460136/original/file-20220427-16-5v9rcq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/460136/original/file-20220427-16-5v9rcq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/460136/original/file-20220427-16-5v9rcq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/460136/original/file-20220427-16-5v9rcq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/460136/original/file-20220427-16-5v9rcq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/460136/original/file-20220427-16-5v9rcq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/460136/original/file-20220427-16-5v9rcq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=377&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The center of the Milky Way galaxy may be home to intelligent life, but some researchers think contacting aliens is a bad idea.</span>
<span class="attribution"><a class="source" href="http://photojournal.jpl.nasa.gov/catalog/PIA12348">NASA/JPL-Caltech/ESA/CXC/STScI</a></span>
</figcaption>
</figure>
<h2>Ethical questions</h2>
<p>The prospect of alien contact is ripe with ethical questions, and METI is no exception.</p>
<p>The first is: <a href="https://setiathome.berkeley.edu/meti_statement_0.html">Who speaks for Earth</a>? In the absence of any international consultation with the public, decisions about what message to send and where to send it are in the hands of a <a href="https://www.newyorker.com/books/joshua-rothman/the-man-who-speaks-for-earth">small group of interested scientists</a>. </p>
<p>But there is also a much deeper question. If you are lost in the woods, getting found is obviously a good thing. When it comes to whether humanity should be broadcasting a message to aliens, the answer is much less clear-cut.</p>
<p>[<em>Understand new developments in science, health and technology, each week.</em> <a href="https://memberservices.theconversation.com/newsletters/?nl=science&source=inline-science-understand">Subscribe to The Conversation’s science newsletter</a>.]</p>
<p>Before he died, iconic physicist <a href="https://www.space.com/34184-stephen-hawking-afraid-alien-civilizations.html">Stephen Hawking was outspoken about the danger</a> of contacting aliens with superior technology. He argued that they could be malign and if given Earth’s location, might destroy humanity. <a href="https://www.ibtimes.co.uk/meti-president-doug-vakoch-aliens-are-not-dangerous-we-could-make-contact-by-2035-1543965">Others see no extra risk</a>, since a truly advanced civilization would already know of our existence. And there is interest. Russian-Israeli billionaire Yuri Milner <a href="https://www.nbcnews.com/storyline/the-big-questions/why-these-scientists-fear-contact-space-aliens-n717271">has offered $1 million</a> for the best design of a new message and an effective way to transmit it. </p>
<p>To date, no international regulations govern METI, so the experiments will continue, despite concerns. </p>
<p>For now, intelligent aliens remain in the realm of science fiction. Books like “<a href="https://www.npr.org/2014/11/13/363123510/three-body-problem-asks-a-classic-sci-fi-question-in-chinese">The Three-Body Problem</a>” by Cixin Liu offer somber and thought-provoking perspectives on what the success of METI efforts might look like. It doesn’t end well for humanity in the books. If humans ever do make contact in real life, I hope the aliens come in peace.</p>
<p><em>This story has been updated to clarify where the Pioneer and Voyager spacecraft are in relation to the Solar System.</em></p><img src="https://counter.theconversation.com/content/182036/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Chris Impey receives funding from the National Science Foundation.</span></em></p>This year, two groups of astronomers plan to send messages containing information about humans and the location of Earth toward parts of space they think may be home to intelligent life.Chris Impey, University Distinguished Professor of Astronomy, University of ArizonaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1792432022-03-28T12:37:15Z2022-03-28T12:37:15ZAstronomy’s 10-year wish list: Big money, bigger telescopes and the biggest questions in science<figure><img src="https://images.theconversation.com/files/454218/original/file-20220324-27-noyr0p.jpg?ixlib=rb-1.1.0&rect=2%2C29%2C1464%2C924&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Hubble Space Telescope was born from a previous decadal survey. What leaps forward will come from this one?</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/nasa2explore/9772693411/in/photolist-fTzBgZ-fV7Nk9-fQaif5-fWzu7e-fTBCFF-fV7KZh-fWHXsP-5h3tfy-6ntttp-fWznYG-fWzU9R-fWHXsZ-fTBgaC-6gJpSm-fWHBSs-6nttrR-fWzj7z-fgjn2y-fWzjfk-5hdDA9-5h9hLv-5h9hrv-fWzuwx-6cZGVe-fV84vM-6nttwi-6nxAXS-6d4RFY-fTB8nm-fWxNSU-fWy8JU-fV7KDY-6d4RAA-fWxrAA-6fXHbJ-fV7Na9-fV84oH-fTB85j-6d6CVo-fWy9Tq-fg8qA3-fWyfu7-fWxyLj-6fTwAk-fWxz2N-fV88pZ-6fXH8C-6nLgWt-6fXH2o-6nQraS">NASA Johnson/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p>It takes expensive tools to learn about the universe, but projects like the <a href="https://www.vla.nrao.edu/">Very Large Array for radio astronomy</a> in New Mexico and the <a href="https://www.nasa.gov/mission_pages/chandra/main/index.html">Chandra X-ray Observatory</a>, which orbits Earth, have pushed scientific knowledge forward in ways that would not have been possible without these instruments. Every 10 years, astronomers and astrophysicists outline priorities for the hardware they need in the decadal survey on astronomy and astrophysics. The newest version of the survey was published by the National Academies of Sciences, Engineering and Medicine in late 2021, and debates about funding are in full swing for the next fiscal year.</p>
<p>I’m a professor of astronomy whose <a href="https://scholar.google.com/citations?user=OrRLRQ4AAAAJ&hl=en">research</a> has depended on facilities and equipment built after a recommendation in one of these decadal surveys, and I was involved in <a href="https://www.nap.edu/catalog/12982/panel-reports-new-worlds-new-horizons-in-astronomy-and-astrophysics">the previous survey</a>, published in 2010. </p>
<p>The<a href="https://www.nationalacademies.org/our-work/decadal-survey-on-astronomy-and-astrophysics-2020-astro2020"> most recent wish list</a> is full of fascinating projects, and it will be exciting to see which get funded and what research will come from them.</p>
<h2>A meeting of the minds</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/454196/original/file-20220324-19-l2a6rr.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="The cover of the report showing planets and stars." src="https://images.theconversation.com/files/454196/original/file-20220324-19-l2a6rr.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/454196/original/file-20220324-19-l2a6rr.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=776&fit=crop&dpr=1 600w, https://images.theconversation.com/files/454196/original/file-20220324-19-l2a6rr.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=776&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/454196/original/file-20220324-19-l2a6rr.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=776&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/454196/original/file-20220324-19-l2a6rr.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=975&fit=crop&dpr=1 754w, https://images.theconversation.com/files/454196/original/file-20220324-19-l2a6rr.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=975&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/454196/original/file-20220324-19-l2a6rr.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=975&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The new report sets detailed goals for the next decade and beyond for astronomy and astrophysics research.</span>
<span class="attribution"><a class="source" href="https://www.nap.edu/catalog/26141/pathways-to-discovery-in-astronomy-and-astrophysics-for-the-2020s">National Academies of Science, Engineering and Medicine</a></span>
</figcaption>
</figure>
<p>Every 10 years since the 1960s, U.S. astronomers and astrophysicists have gathered to create a priority list for new facilities and instruments.</p>
<p>The decadal survey of astronomers is influential because it forces everyone to be on the same page and make hard choices. It has to <a href="https://www.planetary.org/articles/the-2020-astrophysics-decadal-survey-guide">temper ambition with realism</a>, but when astronomers and astrophysicists from the many subfields all work together, they come up with ideas that advance the whole field.</p>
<p>The most <a href="https://www.nationalacademies.org/our-work/decadal-survey-on-astronomy-and-astrophysics-2020-astro2020">recent report</a> is titled “Pathways to Discovery in Astronomy and Astrophysics for the 2020s.” It’s directed at Congress and the three federal agencies that fund most astronomical research: NASA, the National Science Foundation and the Department of Energy. Billions of dollars are at stake.</p>
<p>Producing the reports is a massive undertaking, involving 20 people on the main committee and over 1,000 contributing to the final report. The committee reviewed <a href="https://baas.aas.org/astro2020-science">573 white papers</a> all arguing for specific projects and astronomical capabilities. The finished report runs 615 pages, and it’s not light reading.</p>
<p>This approach works. Some of NASA’s most ambitious and fruitful scientific missions – like the Hubble and James Webb space telescopes – were proposed in and funded through decadal surveys. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/454215/original/file-20220324-25-750p9f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An artists representation of an exoplanet." src="https://images.theconversation.com/files/454215/original/file-20220324-25-750p9f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/454215/original/file-20220324-25-750p9f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/454215/original/file-20220324-25-750p9f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/454215/original/file-20220324-25-750p9f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/454215/original/file-20220324-25-750p9f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/454215/original/file-20220324-25-750p9f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/454215/original/file-20220324-25-750p9f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Gaining better knowledge of planets outside the solar system – and searching them for signs of life – is a major goal the research community listed in the report.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Kepler186f-ArtistConcept-20140417.jpg#/media/File:Kepler186f-ArtistConcept-20140417.jpg">NASA Ames/SETI Institute/JPL-Caltech via Wikimedia Commons</a></span>
</figcaption>
</figure>
<h2>Big science</h2>
<p>The committee identified 24 key science questions for the next generation of astronomy. These fall into three major themes that are science at the biggest scale, and the facilities on the wish list are designed to address these themes.</p>
<p>First is the study of Earth-like worlds. Thanks to explosive growth in the <a href="https://exoplanets.nasa.gov/discovery/exoplanet-catalog/">discovery of exoplanets</a>, the number of known planets outside the solar system has been <a href="https://exoplanets.nasa.gov/faq/6/how-many-exoplanets-are-there/">doubling</a> roughly every two years. Among the <a href="https://exoplanets.nasa.gov/news/1702/cosmic-milestone-nasa-confirms-5000-exoplanets/">more than 5,000</a> known exoplanets are several hundred that are <a href="https://dx.doi.org/10.1073%2Fpnas.1319909110">similar to Earth</a> and could potentially support life. A major goal for the next decade is to build new large telescopes on the ground and in space with instruments that can <a href="https://doi.org/10.1073/pnas.1304213111">“sniff” the atmospheres</a> of Earth-like planets to try to detect gases like oxygen that are created by microbes.</p>
<p>Second is to advance <a href="https://astronomy.com/magazine/news/2021/06/the-age-of-multi-messenger--astronomy">multimessenger astronomy</a> – a relatively new field of astrophysics that takes information about <a href="https://theconversation.com/ligo-detects-more-gravitational-waves-from-even-more-ancient-and-distant-black-hole-collisions-78571">gravitational waves</a>, <a href="https://theconversation.com/the-standard-model-of-particle-physics-the-absolutely-amazing-theory-of-almost-everything-94700">elementary particles</a> and <a href="https://theconversation.com/explainer-what-is-the-electromagnetic-spectrum-8046">electromagnetic radiation</a> and combines it all to gain deeper insights into the underlying astrophysics of the universe. In this case, the need is not so much for new scientific tools but for more grants to enable researchers to collaborate and share data. The science goal is to learn more about cosmic explosions and mergers of compact objects like neutron stars and black holes. </p>
<p>The final theme is the study of <a href="https://blog.oup.com/2020/11/supermassive-black-holes-monsters-in-the-early-universe/">cosmic ecosystems</a>, especially the origin and evolution of galaxies and the massive black holes at their centers. By looking at extremely distant galaxies, astronomers can look into the past, since light takes time to reach Earth. So to understand these massive, complicated systems, scientists will need giant optical telescopes to find galaxies far away in the young universe, as well as radio telescopes to peer into their dusty hearts and reveal the black holes. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/454216/original/file-20220324-21-1kjstrt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A telescope in space next to a large shade structure." src="https://images.theconversation.com/files/454216/original/file-20220324-21-1kjstrt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/454216/original/file-20220324-21-1kjstrt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=343&fit=crop&dpr=1 600w, https://images.theconversation.com/files/454216/original/file-20220324-21-1kjstrt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=343&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/454216/original/file-20220324-21-1kjstrt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=343&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/454216/original/file-20220324-21-1kjstrt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=431&fit=crop&dpr=1 754w, https://images.theconversation.com/files/454216/original/file-20220324-21-1kjstrt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=431&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/454216/original/file-20220324-21-1kjstrt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=431&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The report requested a large telescope to study exoplanets, similar to one NASA has developed that would use a shade to block light from a distant star to facilitate the study of planets around that star.</span>
<span class="attribution"><a class="source" href="http://photojournal.jpl.nasa.gov/catalog/PIA20911">NASA/JPL</a></span>
</figcaption>
</figure>
<h2>Astronomy’s wish list</h2>
<p>Here are a few particularly exciting highlights from the hundreds of items on the wish list.</p>
<p>First, the report recommends spending US$1 billion on developing technology with which to build the next generation of “<a href="https://www.space.com/nasa-great-observatories-space-telescope-decadal-survey">great observatories</a>” in space. The flagship of these missions – to be launched in the 2040s with an eye-popping price tag of $11 billion – would be an <a href="https://aerospaceamerica.aiaa.org/decadal-survey-wants-nasa-to-rethink-how-it-designs-space-telescopes/">optical telescope with a massive 20-foot (6-meter) mirror</a>. This mirror would be eight times bigger than Hubble’s and would be designed to study Earth-like planets in other solar systems – and potentially detect life. The report also recommends building <a href="https://www.aip.org/fyi/2021/astro2020-decadal-survey-arrives-priorities-major-facilities">two smaller space telescopes</a> to work at infrared and X-ray wavelengths, each at a cost of $3 billion to $5 billion.</p>
<p>But orbital efforts are not the only aims of the report. The report also asks for funds to build a giant optical telescope on Earth with a diameter of 80 to 100 feet (25 to 30 meters). That’s five to seven times the light-collecting area of today’s largest telescope. <a href="https://www.science.org/content/article/rival-giant-telescopes-join-forces-seek-us-funding">Two proposals</a> are competing to build this telescope, which would cost close to $2 billion.</p>
<p>The report also calls for the National Science Foundation to spend $3 billion on a new array of <a href="https://ngvla.nrao.edu/">263 radio telescopes</a> that would span the entire U.S. This telescope array could produce radio images with 10 times the sensitivity and 20 times the sharpness of any previous facility, allowing scientists to see deeper into the universe and discover previously undetectable objects. Another item on the wish list is a $650 million pair of <a href="https://cmb-s4.org/">microwave telescopes in Chile and Antarctica</a> that would map the afterglow of the Big Bang.</p>
<p>This kind of money is needed to achieve scientific goals of this scope.</p>
<h2>State of the profession</h2>
<p>Science is more than just the pursuit of knowledge. As part of recent decadal surveys, astronomers and astrophysicists have taken the opportunity to gaze inward and judge the state of the profession. This includes looking at diversity and inclusion, workplace climates and the contributions of astronomers to education and outreach.</p>
<p>[<em>Like what you’ve read? Want more?</em> <a href="https://memberservices.theconversation.com/newsletters/?source=inline-likethis">Sign up for The Conversation’s daily newsletter</a>.]</p>
<p>These fields are overwhelmingly white, with people from minority backgrounds making up <a href="https://www.aip.org/statistics/reports/beyond-representation-data-improve-situation-women-and-minorities-physics-and">only 4% of faculty and students</a>. In an appendix to the report, teams <a href="https://www.nationalacademies.org/our-work/astro2020-panel-on--stateof-the-profession-and-societal-impacts">suggested a number of remedies</a> for the lack of diversity and equity. These <a href="https://nap.edu/resource/26141/interactive/">included ideas</a> such as better mentoring to reduce the high attrition rate for minority students, along with funding for bridge programs to help minorities get established early in their careers and to treat harassment and discrimination as forms of <a href="https://doi.org/10.1038/d41586-018-05076-2">scientific misconduct</a>.</p>
<p>If even a small part of the wish list becomes reality, it will not only increase our understanding of the universe, but also – just as importantly – lead to a more diverse and compassionate astronomy and astrophysics community.</p><img src="https://counter.theconversation.com/content/179243/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Chris Impey receives funding from the National Science Foundation. </span></em></p>The astronomy and astrophysics decadal survey for the 2020s lays out plans to search for life on distant planets, understand the formation of galaxies and solve deep mysteries of physics.Chris Impey, University Distinguished Professor of Astronomy, University of ArizonaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1722842022-01-06T13:12:25Z2022-01-06T13:12:25ZReal shooting stars exist, but they aren’t the streaks you see in a clear night sky<figure><img src="https://images.theconversation.com/files/438524/original/file-20211220-13-qw05dm.jpeg?ixlib=rb-1.1.0&rect=1279%2C294%2C970%2C829&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Some stars travel at high speeds through the universe and sometimes leave spectacular clouds of dust and gas in their wake. </span> <span class="attribution"><a class="source" href="https://esahubble.org/images/opo0903a/">NASA, ESA and R. Sahai (NASA's Jet Propulsion Laboratory)</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>“I see thy glory like a shooting star.”</p>
<p>So says the Earl of Salisbury as he ruminates about the future in Shakespeare’s “Richard II.” </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/438527/original/file-20211220-13-pb34p1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A black and white print of many streaks of light in the sky above a small town." src="https://images.theconversation.com/files/438527/original/file-20211220-13-pb34p1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/438527/original/file-20211220-13-pb34p1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=919&fit=crop&dpr=1 600w, https://images.theconversation.com/files/438527/original/file-20211220-13-pb34p1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=919&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/438527/original/file-20211220-13-pb34p1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=919&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/438527/original/file-20211220-13-pb34p1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1154&fit=crop&dpr=1 754w, https://images.theconversation.com/files/438527/original/file-20211220-13-pb34p1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1154&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/438527/original/file-20211220-13-pb34p1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1154&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Shooting stars – such as those produced by the Leonid meteor shower depicted in this print from 1889 – are beautiful, but they have nothing to do with real stars.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Leonids#/media/File:Leonids-1833.jpg">Adolf Vollmy/WikimediaCommons</a></span>
</figcaption>
</figure>
<p>During the English Renaissance, people believed shooting stars were luminaries falling from the heavens and <a href="https://doi.org/10.2307/776821">harbingers of calamity</a>. But by the end of the 19th century, <a href="https://doi.org/10.1016/0083-6656(82)90010-1">scientists had established</a> the truth to be far more mundane. What today are commonly called <a href="https://theconversation.com/curious-kids-what-makes-a-shooting-star-fall-111068">shooting or falling stars</a> are simply small pieces of rock or dust that quickly burn up upon entering Earth’s atmosphere. </p>
<p>But nature has a surprise for you – shooting stars really do exist.</p>
<p><a href="https://sites.google.com/a/cfa.harvard.edu/idanginsburg/home">I am an astrophysicist</a> who studies <a href="http://www.scholarpedia.org/article/Celestial_mechanics">celestial mechanics</a> – how objects like stars, planets and galaxies move. </p>
<p>From 2005 to 2014, a monumental <a href="https://doi.org/10.1088/0004-637X/787/1/89">observing program</a> incorporating the <a href="https://www.sdss.org/">Sloan Digital Sky Survey</a> and telescopes at the <a href="https://www.cfa.harvard.edu/facilities-technology/cfa-facilities/fred-lawrence-whipple-observatory-mt-hopkins-az">Fred Lawrence Whipple Observatory</a> confirmed a new class of stars that move with such incredible speed that they can escape the gravity of their home galaxies. </p>
<p>Astronomers are just beginning to understand these real-life shooting stars – called <a href="https://doi.org/10.1146/annurev-astro-082214-122230">hypervelocity stars</a> – that zoom through the cosmos at millions of miles per hour. </p>
<h2>Spinning stars and slingshots</h2>
<p>The story of hypervelocity stars begins in 1988, when Jack Gilbert Hills, a theoretician at <a href="https://www.lanl.gov/">Los Alamos National Labs</a>, had an inspired idea: What would happen if a binary star system – that is, two stars that are gravitationally bound to each other and orbit a common center of mass – traveled near the massive black hole at the center of the Milky Way? <a href="https://doi.org/10.1038/331687a0">Hills calculated</a> that the <a href="https://spacemath.gsfc.nasa.gov/blackh/4Page33.pdf">tidal force</a> of the black hole could rend the binary system in two. </p>
<p>Imagine two ice skaters holding hands and spinning around until they all of a sudden let go. The two skaters will fly away from each other. Similarly, when two stars in a binary system are wrenched apart by a close encounter with a black hole, they will fly apart. In such an encounter one star might gain enough energy to be slingshotted out of the galaxy entirely. </p>
<p>Astronomers now know that this is how hypervelocity stars are born. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/438529/original/file-20211220-13-1fiwrso.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A bluish white star leaving the Milky Way galaxy." src="https://images.theconversation.com/files/438529/original/file-20211220-13-1fiwrso.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/438529/original/file-20211220-13-1fiwrso.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=480&fit=crop&dpr=1 600w, https://images.theconversation.com/files/438529/original/file-20211220-13-1fiwrso.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=480&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/438529/original/file-20211220-13-1fiwrso.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=480&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/438529/original/file-20211220-13-1fiwrso.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=603&fit=crop&dpr=1 754w, https://images.theconversation.com/files/438529/original/file-20211220-13-1fiwrso.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=603&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/438529/original/file-20211220-13-1fiwrso.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=603&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A hypervelocity star, HE 0437-5439, was thrown from the center of the Milky Way and is on a one-way trip out of the galaxy.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/mission_pages/hubble/science/expelled-star.html">NASA, ESA and G. Bacon (STScI)</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Theory, observations and simulations</h2>
<p>After the publication of Hills’ prescient paper, the astronomy community considered hypervelocity stars an intriguing possibility, albeit one without observational evidence. That changed in 2005. </p>
<p>While observing stars in the <a href="https://theconversation.com/dark-matter-and-the-milky-way-more-little-than-large-32792">Milky Way’s halo</a>, a team of researchers using the <a href="https://www.mmto.org/">MMT Observatory</a> in Arizona came across something most unexpected. They observed a star escaping the Milky Way at nearly 2 million mph (3.2 million kph). This was <a href="https://doi.org/10.1086/429378">HVS1</a>, the first known hypervelocity star. </p>
<p>Observations tell part of the story, but to help answer other questions – such as what happens to the companion after it separates from the hypervelocity star – my adviser and I turned to computer simulations. Our models predict that the other star in the former pair is often <a href="https://doi.org/10.1111/j.1365-2966.2006.10091.x">left orbiting the black hole</a> in much the same fashion as the Earth orbits the Sun.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/438530/original/file-20211220-15-14excla.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Many blue circular lines against the backdrop of space." src="https://images.theconversation.com/files/438530/original/file-20211220-15-14excla.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/438530/original/file-20211220-15-14excla.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=366&fit=crop&dpr=1 600w, https://images.theconversation.com/files/438530/original/file-20211220-15-14excla.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=366&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/438530/original/file-20211220-15-14excla.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=366&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/438530/original/file-20211220-15-14excla.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=460&fit=crop&dpr=1 754w, https://images.theconversation.com/files/438530/original/file-20211220-15-14excla.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=460&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/438530/original/file-20211220-15-14excla.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=460&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Simulations use the laws of physics to calculate the orbits and trajectories of stars, including hypervelocity stars.</span>
<span class="attribution"><a class="source" href="https://www.eso.org/public/images/eso1825d/">ESO/L. Calçada/spaceengine.org</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Another exciting result from these modeling efforts was the discovery that sometimes the <a href="https://doi.org/10.1111/j.1365-2966.2007.11461.x">two stars can crash into each other</a>. When this happens, the stars may coalesce into one very massive star.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/438531/original/file-20211220-23-ylozwp.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A dark planet against the backdrop of the Milky Way." src="https://images.theconversation.com/files/438531/original/file-20211220-23-ylozwp.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/438531/original/file-20211220-23-ylozwp.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=785&fit=crop&dpr=1 600w, https://images.theconversation.com/files/438531/original/file-20211220-23-ylozwp.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=785&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/438531/original/file-20211220-23-ylozwp.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=785&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/438531/original/file-20211220-23-ylozwp.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=986&fit=crop&dpr=1 754w, https://images.theconversation.com/files/438531/original/file-20211220-23-ylozwp.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=986&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/438531/original/file-20211220-23-ylozwp.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=986&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Planets might also be flung out of the galaxy at stupefying speeds.</span>
<span class="attribution"><a class="source" href="https://insider.si.edu/2012/03/planet-starship-runaway-planets-zoom-at-a-fraction-of-light-speed/">David A. Aguilar/CfA</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>If you were wondering what might befall a planet orbiting one of these stars, we modeled that too. In a <a href="https://doi.org/10.1111/j.1365-2966.2012.20930.x">short paper from 2012</a>, my colleagues and I showed that the black hole in the center of our galaxy can blast planets out of the Milky Way at nearly 5% the speed of light.</p>
<p>As of today, no hypervelocity planets have been detected, but <a href="https://doi.org/10.1093/mnras/stw3213">they very well might be out there</a>, waiting for some happy astronomers to chance upon them.</p>
<h2>Not all fast stars leave the galaxy</h2>
<p>Utilizing data from the <a href="https://sci.esa.int/web/gaia">Gaia spacecraft</a>, launched in 2013, my colleagues and I discovered that some of the stars that the astronomy community had previously considered “hypervelocity stars” are in fact <a href="https://doi.org/10.1093/mnras/sty1601">likely bound to the Milky Way galaxy</a>. </p>
<p>While this result may sound disappointing, it actually reveals two critical points. First, there are different mechanisms to accelerate stars to high speeds. Today astronomers know of <a href="https://doi.org/10.1063/PT.3.3199">thousands of speedy stars</a>. However, just because a star is moving fast does not necessarily make it a hypervelocity star unbound from the Milky Way. Second, true hypervelocity stars that are escaping the Milky Way may be rarer than previously thought. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/438532/original/file-20211220-15-t4nakp.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A circular spacecraft in space." src="https://images.theconversation.com/files/438532/original/file-20211220-15-t4nakp.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/438532/original/file-20211220-15-t4nakp.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/438532/original/file-20211220-15-t4nakp.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/438532/original/file-20211220-15-t4nakp.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/438532/original/file-20211220-15-t4nakp.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/438532/original/file-20211220-15-t4nakp.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/438532/original/file-20211220-15-t4nakp.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Data from both ground- and space-based telescopes like Gaia help astronomers learn more about all types of high-velocity stars, including hypervelocity stars.</span>
<span class="attribution"><a class="source" href="https://solarsystem.nasa.gov/missions/gaia/in-depth/">ESA</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>The future is bright and fast</h2>
<p>I find it beautiful that true shooting stars exist. It’s equally amazing that studying their trajectories and velocities can help answer some of the foremost questions in science today. </p>
<p>For instance, hypervelocity stars could offer clues to the <a href="https://doi.org/10.1086/496958">nature and distribution of dark matter</a> in the universe. Hypervelocity stars may also be the key to answering whether there is <a href="https://theconversation.com/supermassive-black-hole-at-the-center-of-our-galaxy-may-have-a-friend-128295">more than one black hole</a> at the center of the galaxy. </p>
<p>My students are using NASA’s <a href="https://tess.mit.edu/">Transiting Exoplanet Survey Satellite</a> to search for planets around these blisteringly fast stars. The discovery of even one planet around a hypervelocity star will forever change ideas of planetary formation and survivability. </p>
<p>These stars are speedy, but slowly they are shedding light on nature’s secrets. While you may not be able to see a real shooting star with your own eyes, you certainly can make a wish upon one.</p>
<p>[<em>The Conversation’s science, health and technology editors pick their favorite stories.</em> <a href="https://memberservices.theconversation.com/newsletters/?nl=science&source=inline-science-favorite">Weekly on Wednesdays</a>.]</p><img src="https://counter.theconversation.com/content/172284/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Much of the research on hypervelocity stars conducted by Idan Ginsburg and discussed in this article was made possible from various grants and institutions, all of which are properly acknowledged in the relevant published journal articles and available online. </span></em></p>Hypervelocity stars were discovered only 15 years ago and are the closest things in existence to real shooting stars. They travel at millions of miles per hour, so fast that they can escape from galaxies.Idan Ginsburg, Academic Faculty in Physics & Astronomy, Georgia State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1695622021-11-04T16:05:35Z2021-11-04T16:05:35ZYour smile’s cosmic history: we discovered the origin of fluoride in early galaxies<figure><img src="https://images.theconversation.com/files/430101/original/file-20211103-25-10jnbn2.jpg?ixlib=rb-1.1.0&rect=0%2C74%2C958%2C834&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Flouride is created by Wolf–Rayet stars, here seen in the Milky Way by the Hubble Space Telescope. </span> <span class="attribution"><span class="source">Nasa/Judy Schmidt</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Look at the ingredients on a tube of toothpaste and you will probably read something like “contains sodium fluoride”. Fluoride, as you probably know, is important for healthy teeth. <a href="https://www.nature.com/articles/news040119-8">It strengthens enamel</a>, the hard, protective layer around a tooth, and so helps prevent cavities. </p>
<p>You may not think too deeply about toothpaste. But like all things on Earth, from the majestic to the mundane, fluoride - and the story of a smile - has a cosmic origin. Now, my colleagues and I have <a href="https://www.nature.com/articles/s41550-021-01515-9">published a paper in Nature Astronomy</a> that sheds some light on it.</p>
<p>Virtually all natural elements were formed long ago in the history of the universe. Hydrogen is the oldest element: it formed very shortly after the big bang, about 14 billion years ago. Within a few minutes of the big bang, the light elements <a href="https://w.astro.berkeley.edu/%7Emwhite/darkmatter/bbn.html">helium, deuterium and lithium</a> were also formed in a process called <a href="https://w.astro.berkeley.edu/%7Emwhite/darkmatter/bbn.html">big bang nucleosynthesis</a>. Since then, nearly every other element has been forged in processes associated with the <a href="https://theconversation.com/piercing-the-mystery-of-the-cosmic-origins-of-gold-88880">life and death of stars</a>. But those stars were not always around. </p>
<figure class="align-center ">
<img alt="Image of toothpaste." src="https://images.theconversation.com/files/430041/original/file-20211103-25-f9f941.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/430041/original/file-20211103-25-f9f941.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/430041/original/file-20211103-25-f9f941.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/430041/original/file-20211103-25-f9f941.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/430041/original/file-20211103-25-f9f941.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/430041/original/file-20211103-25-f9f941.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/430041/original/file-20211103-25-f9f941.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Do you consider the cosmic origins of your toothpaste when brushing your teeth?</span>
<span class="attribution"><span class="source">Pixabay</span></span>
</figcaption>
</figure>
<p>We still don’t know exactly when the first stars ignited in the universe, but it probably didn’t happen for about <a href="https://theconversation.com/after-our-universes-cosmic-dawn-what-happened-to-all-its-original-hydrogen-65527">100 million years or so after the big bang</a>. Before this, the universe was filled with a fog of hydrogen, mingled with the mysterious, invisible substance astronomers call dark matter. This fog was not smooth, but rippled - slightly denser in some places. It was these regions that started to contract, or “collapse”, due to gravity, to form the first galaxies. Where the gas got dense enough, stars ignited and lit up the universe.</p>
<p>The following few billion years was a time of rapid growth: the rate of star formation in the universe rose sharply until it reached a peak, 8 to 10 billion years ago. Ever since that “cosmic noon”, the overall rate of star formation in the universe has been in decline. That’s why astronomers are so interested in the early phases of the history of the cosmos: what happened then shaped what we see around us today. </p>
<p>While we have quite a lot of information about how the growth of galaxies “ramped up” in terms of their star formation, we have relatively little insight into their chemical evolution at the earliest times. This is important because, as stars live and die, the elements they produce become dispersed throughout a galaxy and beyond. Many years later, some of those elements can form new planets like ours. </p>
<h2>Rapid evolution</h2>
<p>We observed a distant galaxy called NGP-190387 with the <a href="https://www.almaobservatory.org/en/home/">Atacama Large Millimetre/sub-millimetre Array</a> (Alma) - a telescope that detects light with a wavelength of around one millimetre. This allows us to see the light emitted by cold dust and gas in distant galaxies. The data revealed something unexpected: a dip in the light at a wavelength of exactly 1.32 millimetres. This corresponds exactly to the wavelength at which the molecule hydrogen fluoride (HF), comprising a hydrogen atom and fluorine atom, absorbs light (taking into account a shift in wavelength that happens due to the universe’s expansion). The deficit of light implies the presence of clouds of hydrogen fluoride gas in the galaxy. This light has taken over 12 billion years to reach us, and we see the galaxy as it was when the universe was 1.4 billion years old.</p>
<p>This is exciting, because it provides information about how galaxies first became enriched with chemical elements shortly after they first formed. We can see that even at this early time, NGP-190387 had a high abundance of fluorine. Although we have observed other elements in distant galaxies, such as carbon, nitrogen and oxygen, this is the first time fluorine has been detected in a star-forming galaxy at such a distance. The greater the variety of elements we can observe in early galaxies, the better our understanding of the process of chemical enrichment at that time.</p>
<p>We know that fluorine can be produced in different ways: for example, in star explosions called supernovas and in certain <a href="https://en.wikipedia.org/wiki/Asymptotic_giant_branch">“asymptotic giant branch”</a> stars - red supergiant stars nearing the end of their life, having burned most of the hydrogen and helium in their cores and now swollen in size. </p>
<p>Models of how elements form in stars and in supernovae can tell us how much fluorine we should expect from these sources. And we found that the abundance of fluorine was too high in NGP-190387 to be explained by supernovas and asymptotic giant branch stars alone. An extra source was needed, and this is probably another type of star called a <a href="https://astronomy.swin.edu.au/cosmos/w/wolf-rayet+star">Wolf-Rayet</a>. Wolf-Rayet stars are quite rare – there are only a few hundred catalogued in the Milky Way, for example. But they are extreme. </p>
<figure class="align-center ">
<img alt="The Hubble Ultra Deep Field" src="https://images.theconversation.com/files/430034/original/file-20211103-27-o51gsc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/430034/original/file-20211103-27-o51gsc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/430034/original/file-20211103-27-o51gsc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/430034/original/file-20211103-27-o51gsc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/430034/original/file-20211103-27-o51gsc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/430034/original/file-20211103-27-o51gsc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/430034/original/file-20211103-27-o51gsc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Ancient galaxies seen by the Hubble Space Telescpope.</span>
<span class="attribution"><span class="source">NASA/ESA</span></span>
</figcaption>
</figure>
<p>Wolf-Rayet stars are a phase in the lifecycle of very massive stars – with more than ten times the mass of our Sun. Approaching the end of their short life, these stars burn helium in their cores, and are millions of times more luminous than the Sun. Unusually, Wolf-Rayet stars have lost their envelope of hydrogen via powerful winds, leaving the helium core exposed. They will eventually explode in dramatic core-collapse supernova explosions. When we added the amount of fluorine expected from Wolf-Rayet stars to our model, we could finally account for the dip in light from NGP-190387. </p>
<p>This adds to a growing body of evidence that shows that the growth of galaxies was surprisingly fast-paced in the early universe: a frenzy of star formation and chemical enrichment. Those processes lay the foundations for the universe we see around us today, and this work provides new insight into the detailed astrophysics at play, over 12 billion years ago. </p>
<p>But perhaps the main take away is that it shows that the story of your smile is a tale as old as time.</p><img src="https://counter.theconversation.com/content/169562/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>James Geach receives funding from The Royal Society and the Science and Technology Facilities Council. </span></em></p>Tracing the cosmic origin of toothpaste, scientists got a glimpse into the surprising chemistry of early galaxies.James Geach, Professor of Astrophysics and Royal Society University Research Fellow, University of HertfordshireLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1698052021-11-01T12:26:16Z2021-11-01T12:26:16ZA small telescope past Saturn could solve some mysteries of the universe better than giant telescopes near Earth<figure><img src="https://images.theconversation.com/files/429193/original/file-20211028-27-1f4qlx4.png?ixlib=rb-1.1.0&rect=0%2C186%2C2592%2C1593&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A telescope in the outer solar system would be able to do unique science that is impossible closer to the Sun.</span> <span class="attribution"><span class="source">Michael Zemcov</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Dozens of space-based telescopes operate near Earth and provide incredible images of the universe. But imagine a telescope far away in the outer solar system, 10 or even 100 times farther from the Sun than Earth. The ability to look back at our solar system or peer into the darkness of the distant cosmos would make this a uniquely powerful scientific tool.</p>
<p><a href="https://www.rit.edu/directory/mbzsps-michael-zemcov">I’m an astrophysicist</a> who studies the formation of structure in the universe. Since the 1960s, scientists like me have been considering the important scientific questions we might be able to answer with a telescope placed in the outer solar system. </p>
<p>So what would such a mission look like? And what science could be done?</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/429160/original/file-20211028-25-3re5m6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram showing the Sun and all planets in a line." src="https://images.theconversation.com/files/429160/original/file-20211028-25-3re5m6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/429160/original/file-20211028-25-3re5m6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=227&fit=crop&dpr=1 600w, https://images.theconversation.com/files/429160/original/file-20211028-25-3re5m6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=227&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/429160/original/file-20211028-25-3re5m6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=227&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/429160/original/file-20211028-25-3re5m6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=286&fit=crop&dpr=1 754w, https://images.theconversation.com/files/429160/original/file-20211028-25-3re5m6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=286&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/429160/original/file-20211028-25-3re5m6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=286&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Where a telescope is located matters nearly as much as its power. In many cases, the farther from the Sun, the better.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Solar-System-blank.jpg#/media/File:Solar-System-blank.jpg">Beinahegut/WikimediaCommons</a></span>
</figcaption>
</figure>
<h2>A tiny telescope far from home</h2>
<p>The scientific strength of a telescope far from Earth would come primarily from its location, not its size. Plans for a telescope in the outer solar system would put it somewhere beyond the orbit of Saturn, roughly a billion or more miles from Earth. </p>
<p>We’d need only send a very small telescope – with a lens roughly the size of a small plate – to achieve some truly unique astrophysical insights. Such a telescope could be built to weigh less than 20 pounds (9 kilograms) and could be piggybacked on virtually any <a href="https://interstellarprobe.jhuapl.edu">mission to Saturn or beyond</a>. </p>
<p>Though small and simple compared with telescopes like <a href="https://hubblesite.org">Hubble</a> or <a href="https://www.jwst.nasa.gov/content/webbLaunch/index.html">James Webb</a>, such an instrument operating away from the bright light of the Sun could <a href="https://arxiv.org/pdf/1903.05729.pdf">make measurements</a> that are difficult or <a href="https://arxiv.org/pdf/1802.09536.pdf">outright impossible from a vantage point near the Earth</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/429192/original/file-20211028-13-1wgvq9a.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A picture and graphic showing a disc of dust around a central star." src="https://images.theconversation.com/files/429192/original/file-20211028-13-1wgvq9a.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/429192/original/file-20211028-13-1wgvq9a.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=302&fit=crop&dpr=1 600w, https://images.theconversation.com/files/429192/original/file-20211028-13-1wgvq9a.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=302&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/429192/original/file-20211028-13-1wgvq9a.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=302&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/429192/original/file-20211028-13-1wgvq9a.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=379&fit=crop&dpr=1 754w, https://images.theconversation.com/files/429192/original/file-20211028-13-1wgvq9a.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=379&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/429192/original/file-20211028-13-1wgvq9a.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=379&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Sun has a disc of dust and gas surrounding it, much like the pinkish haze seen in this image and graphical representation of a nearby red dwarf star and its dust cloud.</span>
<span class="attribution"><a class="source" href="https://hubblesite.org/contents/media/images/2013/20/3181-Image.html?news=true">NASA/ESA/J. Debes</a></span>
</figcaption>
</figure>
<h2>Outside looking in</h2>
<p>Unfortunately for astronomers, getting a selfie of the solar system is a challenge. But being able to see the solar system from an outside vantage point would reveal a lot of information, in particular about the shape, distribution and composition of the dust cloud that surrounds the Sun. </p>
<p>Imagine a street lamp on a foggy evening – by standing far away from the lamp, the swirling mists are visible in a way that someone <a href="https://doi.org/10.3847/25c2cfeb.2f064292">standing under the streetlight could never see</a>.</p>
<p>For years astrophysicists have been able to take images of and study the dust discs in solar systems <a href="https://roman.gsfc.nasa.gov/science/Astro2020/ChenChristineH.pdf?version=1&modificationDate=1628623860142&api=v2">around other stars in the Milky Way</a>. But these stars are very far away, and there are <a href="https://www.science.org/content/article/cosmic-conundrum-disks-gas-and-dust-supposedly-form-planets-don-t-seem-have-goods">limits to what astronomers can learn about them</a>. Using observations looking back toward the Sun, astronomers could compare the shape, features and composition of these distant dust clouds with detailed data on Earth’s own solar system. This data would fill gaps in knowledge about solar dust clouds and make it possible to understand the history of production, migration and destruction of dust in other solar systems that there is no hope of traveling to in person.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/429164/original/file-20211028-20-129axtv.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A picture of thousands of galaxies." src="https://images.theconversation.com/files/429164/original/file-20211028-20-129axtv.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/429164/original/file-20211028-20-129axtv.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/429164/original/file-20211028-20-129axtv.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/429164/original/file-20211028-20-129axtv.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/429164/original/file-20211028-20-129axtv.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/429164/original/file-20211028-20-129axtv.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/429164/original/file-20211028-20-129axtv.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The universe is full of galaxies – as seen in this image called the Hubble Ultra Deep Field – and measuring the cumulative light from these is hard to do from Earth.</span>
<span class="attribution"><a class="source" href="https://svs.gsfc.nasa.gov/30946">NASA/JPL</a></span>
</figcaption>
</figure>
<h2>Deep darkness of space</h2>
<p>Another benefit of placing a telescope far from the Sun is the lack of reflected light. The disc of dust in the plane of the planets reflects the Sun’s light back at Earth. This creates a haze that is between <a href="https://ned.ipac.caltech.edu/level5/March17/Cooray/Cooray1.html#1.4">100 and 1,000 times brighter than light from other galaxies</a> and obscures views of the cosmos from near Earth. Sending a telescope outside of this dust cloud would place it in a much darker region of space making it easier to measure the light coming from outside the solar system.</p>
<p>Once there, the telescope could measure the brightness of the ambient light of the universe over a wide range of wavelengths. This could provide insights into how <a href="https://ned.ipac.caltech.edu/level5/Madau2/Mad_contents.html">matter condensed into the first stars and galaxies</a>. It would also enable researchers to test models of the universe by comparing the predicted sum of light from all galaxies with a precise measurement. Discrepancies could point to problems with models of structure formation in the universe or perhaps to <a href="https://royalsocietypublishing.org/doi/10.1098/rsos.150555">exotic new physics</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/429166/original/file-20211028-5568-22i40f.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A blue horseshoe of light surrounding an orange galaxy." src="https://images.theconversation.com/files/429166/original/file-20211028-5568-22i40f.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/429166/original/file-20211028-5568-22i40f.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=396&fit=crop&dpr=1 600w, https://images.theconversation.com/files/429166/original/file-20211028-5568-22i40f.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=396&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/429166/original/file-20211028-5568-22i40f.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=396&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/429166/original/file-20211028-5568-22i40f.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=498&fit=crop&dpr=1 754w, https://images.theconversation.com/files/429166/original/file-20211028-5568-22i40f.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=498&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/429166/original/file-20211028-5568-22i40f.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=498&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">From far enough away, it would be possible to use the Sun as a giant lens, similar to the gravitational lensing seen here as light from a distant blue galaxy is bent around a nearer orange galaxy seen in the center.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Gravitational_lens#/media/File:A_Horseshoe_Einstein_Ring_from_Hubble.JPG">ESA/Hubble/NASA</a></span>
</figcaption>
</figure>
<h2>Into the unknown</h2>
<p>Finally, increasing a telescope’s distance from the Sun would also allow astronomers to do unique science that takes advantage of an <a href="https://hubblesite.org/contents/articles/gravitational-lensing">effect called gravitational lensing</a>, in which a massive object distorts the path light takes as it moves past an object.</p>
<p>One use of gravitational lensing is to <a href="https://theconversation.com/rogue-planets-hunting-the-galaxys-most-mysterious-worlds-149588">search for and weigh rogue planets</a> – planets that roam interstellar space after being ejected from their home solar systems. Since rogue planets don’t emit light on their own, astrophysicists can look for their <a href="https://www.universetoday.com/138141/gravitational-microlensing-method/">effect on the light from background stars</a>. To differentiate between the distance of the lensing object and its mass requires observations from a second location far from Earth.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/429162/original/file-20211028-13882-66luob.gif?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An image showing how a planet will bend the light from a distant star." src="https://images.theconversation.com/files/429162/original/file-20211028-13882-66luob.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/429162/original/file-20211028-13882-66luob.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/429162/original/file-20211028-13882-66luob.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/429162/original/file-20211028-13882-66luob.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/429162/original/file-20211028-13882-66luob.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/429162/original/file-20211028-13882-66luob.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/429162/original/file-20211028-13882-66luob.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Gravitational lensing caused by a planet passing in front of a distant star will bend light from that star, and that can also be used to detect dark planets that have been ejected from solar systems.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Gravitational_lens.gif#/media/File:Gravitational_lens.gif">NASA Ames/JPL-Caltech/T. Pyle via WikimediaCommons</a></span>
</figcaption>
</figure>
<p>In 2011, scientists used a camera on the EPOXI mission to the asteroid belt to discover and weigh a <a href="https://doi.org/10.1088/0004-637X/741/1/22">Neptune-sized object floating free among stars in the Milky Way galaxy</a>. Only a few rogue planets have been found, but astronomers suspect they are very common and could hold clues to the <a href="https://www.abc.net.au/news/2021-07-07/free-floating-planets-nasa-kepler-space-telescope/100273040">formation of solar systems and prevalence of planets around stars</a>.</p>
<p>But perhaps the most interesting use for a telescope in the outer solar system would be the potential to use the <a href="https://www.planetary.org/space-images/solar-gravity-lens-telescope">gravitational field of the Sun itself as a giant lens</a>. This kind of measurement may allow astrophysicists to actually map planets in other star systems. Perhaps one day we will be able to name continents on an Earth-like planet around a distant star.</p>
<p>[<em>Get the best of The Conversation, every weekend.</em> <a href="https://theconversation.com/us/newsletters/weekly-highlights-61?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=weeklybest">Sign up for our weekly newsletter</a>.]</p>
<h2>Coming soon?</h2>
<p>Since Pioneer 10 became the first human-made object to cross Jupiter’s orbit in 1973, there have been only a handful of astrophysical studies done from beyond the orbit of Earth. Missions to the outer solar system are rare, but many teams of scientists are doing <a href="https://www.universetoday.com/138141/gravitational-microlensing-method/">studies to show how an extrasolar telescope project would work</a> and what could be learned from one. </p>
<p>Every 10 years or so, leaders in the astrophysics and astronomy fields gather to set goals for the following decade. That plan for the 2020s is scheduled to be released on Nov. 4, 2021. In it, I expect to see discussions about the next telescope that could revolutionize astronomy. Taking a telescope to the outer solar system, while ambitious, is well within the technological ability of NASA or other space agencies. I hope that one day soon a tiny telescope out on a lonely mission in dark reaches of the solar system will provide us incredible insights into the universe.</p><img src="https://counter.theconversation.com/content/169805/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Zemcov receives funding from the National Aeronautics and Space Administration and the National Science Foundation.</span></em></p>Such a mission could be developed soon, allowing astrophysicists to take selfies of the solar system and use the Sun’s gravity as a lens to peer deep into space.Michael Zemcov, Associate Professor of Physics, Rochester Institute of TechnologyLicensed as Creative Commons – attribution, no derivatives.