tag:theconversation.com,2011:/fr/topics/space-telescopes-16408/articlesSpace telescopes – The Conversation2023-07-12T12:39:24Ztag: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>
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<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>
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<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>
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<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>
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<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>
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<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>
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<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>
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<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>
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<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>
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<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>
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<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>
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<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>
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<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>
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<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>
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<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/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/1947392022-12-22T19:08:04Z2022-12-22T19:08:04Z10 times this year the Webb telescope blew us away with new images of our stunning universe<figure><img src="https://images.theconversation.com/files/501223/original/file-20221215-25-lu4eme.jpg?ixlib=rb-1.1.0&rect=0%2C21%2C3583%2C2042&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Carina star-forming region imaged by the JWST.</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</a></span></figcaption></figure><p>It is no exaggeration to say the James Webb Space Telescope (JWST) represents a new era for modern astronomy.</p>
<p><a href="https://theconversation.com/nasas-james-webb-space-telescope-has-reached-its-destination-1-5-million-km-from-earth-heres-what-happens-next-175327">Launched on December 25 last year</a> and fully operational since July, the telescope offers glimpses of the universe that were inaccessible to us before. Like the Hubble Space Telescope, the JWST is in space, so it can take pictures with stunning detail free from the distortions of Earth’s atmosphere.</p>
<p>However, while Hubble is in orbit around Earth at an altitude of 540km, the JWST is <em>1.5 million</em> kilometres distant, far beyond the Moon. From this position, away from the interference of our planet’s reflected heat, it can collect light from across the universe far into the infrared portion of the electromagnetic spectrum.</p>
<p>This ability, when combined with the JWST’s larger mirror, state-of-the-art detectors, and many other technological advances, allows astronomers to look back to the universe’s earliest epochs.</p>
<p>As the universe expands, it stretches the wavelength of light travelling towards us, making more distant objects appear redder. At great enough distances, the light from a galaxy is shifted entirely out of the visible part of the electromagnetic spectrum to the infrared. The JWST is able to probe such sources of light right back to the earliest times, nearly 14 billion years ago.</p>
<p>The Hubble telescope continues to be a great scientific instrument and can see at optical wavelengths where the JWST cannot. But the Webb telescope can see much further into the infrared with greater sensitivity and sharpness.</p>
<p>Let’s have a look at ten images that have demonstrated the staggering power of this new window to the universe.</p>
<h2>1. Mirror alignment complete</h2>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/501219/original/file-20221215-24-vfv1aq.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A bright six-pointed orange star with text above it stating it's a telescope alignment evaluation image. Inset in the top right corner shows a red blob with two points" src="https://images.theconversation.com/files/501219/original/file-20221215-24-vfv1aq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/501219/original/file-20221215-24-vfv1aq.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=380&fit=crop&dpr=1 600w, https://images.theconversation.com/files/501219/original/file-20221215-24-vfv1aq.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=380&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/501219/original/file-20221215-24-vfv1aq.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=380&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/501219/original/file-20221215-24-vfv1aq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=477&fit=crop&dpr=1 754w, https://images.theconversation.com/files/501219/original/file-20221215-24-vfv1aq.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=477&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/501219/original/file-20221215-24-vfv1aq.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=477&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Left: The first publicly released alignment image from the JWST. Astronomers jumped on this image to compare it to previous images of the same part of sky like that on the right from the Dark Energy Camera on Earth.</span>
<span class="attribution"><span class="source">NASA/STScI/LegacySurvey/C. Jacobs</span></span>
</figcaption>
</figure>
<p>Despite years of testing on the ground, an observatory as complex as the JWST required extensive configuration and testing once deployed in the cold and dark of space.</p>
<p>One of the biggest tasks was getting <a href="https://theconversation.com/the-james-webb-space-telescope-has-taken-its-first-aligned-image-of-a-star-heres-how-it-was-done-178315">the 18 hexagonal mirror segments</a> unfolded and aligned to within a fraction of a wavelength of light. In March, <a href="https://www.nasa.gov/press-release/nasa-s-webb-reaches-alignment-milestone-optics-working-successfully/">NASA released the first image</a> (centred on a star) from the fully aligned mirror. Although it was just a calibration image, astronomers immediately compared it to existing images of that patch of sky – with considerable excitement.</p>
<h2>2. Spitzer vs MIRI</h2>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/499165/original/file-20221206-20-qp5q7u.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two orange images showing a series of bright dots - the left one is much fuzzier than the right one" src="https://images.theconversation.com/files/499165/original/file-20221206-20-qp5q7u.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/499165/original/file-20221206-20-qp5q7u.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=458&fit=crop&dpr=1 600w, https://images.theconversation.com/files/499165/original/file-20221206-20-qp5q7u.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=458&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/499165/original/file-20221206-20-qp5q7u.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=458&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/499165/original/file-20221206-20-qp5q7u.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=575&fit=crop&dpr=1 754w, https://images.theconversation.com/files/499165/original/file-20221206-20-qp5q7u.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=575&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/499165/original/file-20221206-20-qp5q7u.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">This image shows a portion of the ‘Pillars of Creation’ in the infrared (see below); on the left taken with the Spitzer Space Telescope, and JWST on the right. The contrast in depth and resolution is dramatic.</span>
<span class="attribution"><span class="source">NASA/JPL-Caltech (left), NASA/ESA/CSA/STScI (right)</span></span>
</figcaption>
</figure>
<p>This early image, taken while all the cameras were being focused, clearly demonstrates the step change in data quality that JWST brings over its predecessors.</p>
<p>On the left is an image from the Spitzer telescope, a space-based infrared observatory with an 85cm mirror; the right, the same field from JWST’s mid-infrared <a href="https://webb.nasa.gov/content/observatory/instruments/miri.html">MIRI camera</a> and 6.5m mirror. The resolution and ability to detect much fainter sources is on show here, with hundreds of galaxies visible that were lost in the noise of the Spitzer image. This is what a bigger mirror situated out in the deepest, coldest dark can do.</p>
<h2>3. The first galaxy cluster image</h2>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/499268/original/file-20221206-18-h6t99q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two images of hundreds of dots of light on a dark background, with more visible on the right hand side" src="https://images.theconversation.com/files/499268/original/file-20221206-18-h6t99q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/499268/original/file-20221206-18-h6t99q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=308&fit=crop&dpr=1 600w, https://images.theconversation.com/files/499268/original/file-20221206-18-h6t99q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=308&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/499268/original/file-20221206-18-h6t99q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=308&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/499268/original/file-20221206-18-h6t99q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=386&fit=crop&dpr=1 754w, https://images.theconversation.com/files/499268/original/file-20221206-18-h6t99q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=386&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/499268/original/file-20221206-18-h6t99q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=386&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">SMACS 0723 galaxy cluster – from Hubble on the left, and JWST on the right. Hundreds more galaxies are visible in JWST’s infrared image.</span>
<span class="attribution"><span class="source">NASA/STSci</span></span>
</figcaption>
</figure>
<p>The galaxy cluster with the prosaic name of SMACS J0723.3–7327 was a good choice for the first colour images <a href="https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-delivers-deepest-infrared-image-of-universe-yet">released to the public</a> from the JWST.</p>
<p>The field is crowded with galaxies of all shapes and colours. The combined mass of this enormous galaxy cluster, over 4 billion light years away, bends space in such a way that light from distant sources in the background is stretched and magnified, an effect known as <a href="https://hubblesite.org/contents/articles/gravitational-lensing">gravitational lensing</a>.</p>
<p>These distorted background galaxies can be clearly seen as lines and arcs throughout this image. The field is already spectacular in Hubble images (left), but the JWST near-infrared image (right) reveals a wealth of extra detail, including hundreds of distant galaxies too faint or too red to be detected by its predecessor.</p>
<h2>4. Stephan’s Quintet</h2>
<figure class="align-center ">
<img alt="Side-by-side images of four large, luminous circles with thousands of stars in the background and within; the left side has more brightness and sharpness" src="https://images.theconversation.com/files/501816/original/file-20221219-26-k4lphv.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/501816/original/file-20221219-26-k4lphv.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/501816/original/file-20221219-26-k4lphv.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/501816/original/file-20221219-26-k4lphv.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/501816/original/file-20221219-26-k4lphv.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/501816/original/file-20221219-26-k4lphv.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/501816/original/file-20221219-26-k4lphv.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">
<figcaption>
<span class="caption">Hubble (l) and JWST (r) images of the group of galaxies known as ‘Stephan’s Quintet’. The inset shows a zoom-in on a distant background galaxy.</span>
<span class="attribution"><span class="source">NASA/STScI</span></span>
</figcaption>
</figure>
<p>These images depict a spectacular group of galaxies known as Stephan’s Quintet, a group that has <a href="https://www.galactic-hunter.com/post/hcg-92-stephan-s-quintet">long been of interest to astronomers</a> studying the way colliding galaxies interact with one another gravitationally.</p>
<p>On the left we see the Hubble view, and the right <a href="https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-sheds-light-on-galaxy-evolution-black-holes">the JWST mid-infrared view</a>. The inset shows the power of the new telescope, with a zoom in on a small background galaxy. In the Hubble image we see some bright star-forming regions, but only with the JWST does the full structure of this and surrounding galaxies reveal itself.</p>
<h2>5. The Pillars of Creation</h2>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/499170/original/file-20221206-21-drey7v.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two side-by-side images of finger-like protrusions on a multicoloured starry background, wth more detail visible on the right" src="https://images.theconversation.com/files/499170/original/file-20221206-21-drey7v.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/499170/original/file-20221206-21-drey7v.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=290&fit=crop&dpr=1 600w, https://images.theconversation.com/files/499170/original/file-20221206-21-drey7v.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=290&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/499170/original/file-20221206-21-drey7v.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=290&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/499170/original/file-20221206-21-drey7v.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=364&fit=crop&dpr=1 754w, https://images.theconversation.com/files/499170/original/file-20221206-21-drey7v.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=364&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/499170/original/file-20221206-21-drey7v.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=364&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 ‘Pillars of Creation’, a star-forming region of our galaxy, as captured by Hubble (left) and JWST (right).</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/feature/goddard/2022/nasa-s-webb-takes-star-filled-portrait-of-pillars-of-creation">NASA, ESA, CSA, STScI; Joseph DePasquale (STScI), Anton M. Koekemoer (STScI), Alyssa Pagan (STScI)</a></span>
</figcaption>
</figure>
<p>The so-called Pillars of Creation is one of the most famous images in all of astronomy, <a href="https://hubblesite.org/contents/media/images/3862-Image">taken by Hubble in 1995</a>. It demonstrated the extraordinary reach of a space-based telescope.</p>
<p>It depicts a star-forming region in the Eagle Nebula, where interstellar gas and dust provide the backdrop to a stellar nursery teeming with new stars. The image on the right, taken with the <a href="https://webb.nasa.gov/content/observatory/instruments/nircam.html">JWST’s near-infrared camera</a> (NIRCam), demonstrates a further advantage of infrared astronomy: the ability to peer through the shroud of dust and see what lies within and behind. </p>
<h2>6. The ‘Hourglass’ Protostar</h2>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/499203/original/file-20221206-14-wz1k2y.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An orange-and-blue hourglass shape on a dark background, with a blurrier blue image of the same shape in the upper corner" src="https://images.theconversation.com/files/499203/original/file-20221206-14-wz1k2y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/499203/original/file-20221206-14-wz1k2y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=612&fit=crop&dpr=1 600w, https://images.theconversation.com/files/499203/original/file-20221206-14-wz1k2y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=612&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/499203/original/file-20221206-14-wz1k2y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=612&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/499203/original/file-20221206-14-wz1k2y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=769&fit=crop&dpr=1 754w, https://images.theconversation.com/files/499203/original/file-20221206-14-wz1k2y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=769&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/499203/original/file-20221206-14-wz1k2y.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">The ‘hourglass protostar’, a star still in the process of accreting enough gas to begin fusing hydrogen. Inset: A much lower resolution view from Spitzer.</span>
<span class="attribution"><span class="source">NASA/STScI/JPL-Caltech/A. Tobin</span></span>
</figcaption>
</figure>
<p>This image depicts another act of galactic creation within the Milky Way. This hourglass-shaped structure is a cloud of dust and gas surrounding a star in the act of formation – a protostar called L1527.</p>
<p>Only visible in the infrared, an “accretion disk” of material falling in (the black band in the centre) will eventually enable the protostar to gather enough mass to start fusing hydrogen, and a new star will be born.</p>
<p>In the meantime, light from the still-forming star illuminates the gas above and below the disk, making the hourglass shape. Our previous view of this came from Spitzer; the amount of detail is once again an enormous leap ahead.</p>
<h2>7. Jupiter in infrared</h2>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/499258/original/file-20221206-2958-ashu5x.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A turqoise and blue banded sphere with bright orange patches of light at both poles" src="https://images.theconversation.com/files/499258/original/file-20221206-2958-ashu5x.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/499258/original/file-20221206-2958-ashu5x.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=569&fit=crop&dpr=1 600w, https://images.theconversation.com/files/499258/original/file-20221206-2958-ashu5x.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=569&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/499258/original/file-20221206-2958-ashu5x.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=569&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/499258/original/file-20221206-2958-ashu5x.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=715&fit=crop&dpr=1 754w, https://images.theconversation.com/files/499258/original/file-20221206-2958-ashu5x.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=715&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/499258/original/file-20221206-2958-ashu5x.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=715&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An infrared view of Jupiter from the JWST. Note the auroral glow at the poles; this is caused by the interaction of charged particles from the sun with Jupiter’s magnetic field.</span>
<span class="attribution"><span class="source">NASA/STScI</span></span>
</figcaption>
</figure>
<p>The Webb telescope’s mission includes imaging the most distant galaxies from the beginning of the universe, but it can look a little closer to home as well.</p>
<p>Although JWST cannot look at Earth or the inner Solar System planets – as it must always face away from the Sun – it can look outward at the more distant parts of our Solar System. This near-infrared image of Jupiter is a beautiful example, as we gaze deep into the structure of the gas giant’s clouds and storms. The glow of auroras at both the northern and southern poles is haunting.</p>
<p>This image was extremely difficult to achieve due to the fast motion of Jupiter across the sky relative to the stars and because of its fast rotation. The success proved the Webb telescope’s ability to track difficult astronomical targets extremely well.</p>
<h2>8. The Phantom Galaxy</h2>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/499257/original/file-20221206-2849-7pej0e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Three similar images of spiral galaxy in different colours, with the middle one providing the most detail" src="https://images.theconversation.com/files/499257/original/file-20221206-2849-7pej0e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/499257/original/file-20221206-2849-7pej0e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/499257/original/file-20221206-2849-7pej0e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/499257/original/file-20221206-2849-7pej0e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/499257/original/file-20221206-2849-7pej0e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/499257/original/file-20221206-2849-7pej0e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/499257/original/file-20221206-2849-7pej0e.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">Hubble visible light (l), JWST infrared (r) and combined (middle) images of the ‘Phantom Galaxy’ M74. The ability to combine visible light information about stars with infrared images of gas and dust allow us to probe such galaxies in exquisite detail.</span>
<span class="attribution"><span class="source">ESA/NASA</span></span>
</figcaption>
</figure>
<p>These images of the so-called <a href="https://esawebb.org/images/potm2208a/">Phantom Galaxy or M74</a> reveal the power of JWST not only as the latest and greatest of astronomical instruments, but as a valuable complement to other great tools. The middle panel here combines visible light from Hubble with infrared from Webb, allowing us to see how starlight (via Hubble) and gas and dust (via JWST) together shape this remarkable galaxy.</p>
<p>Much JWST science is designed to be combined with Hubble’s optical views and other imaging to leverage this principle.</p>
<h2>9. A super-distant galaxy</h2>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/501222/original/file-20221215-24-ap036o.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Side by side images of a black background with many small galaxies of various shapes glowing faintly" src="https://images.theconversation.com/files/501222/original/file-20221215-24-ap036o.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/501222/original/file-20221215-24-ap036o.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=311&fit=crop&dpr=1 600w, https://images.theconversation.com/files/501222/original/file-20221215-24-ap036o.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=311&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/501222/original/file-20221215-24-ap036o.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=311&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/501222/original/file-20221215-24-ap036o.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=391&fit=crop&dpr=1 754w, https://images.theconversation.com/files/501222/original/file-20221215-24-ap036o.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=391&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/501222/original/file-20221215-24-ap036o.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=391&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 ‘zoom in’ on a galaxy from one of the universe’s earliest epochs, when the universe was only about 300 million years old (the small red source visible in the centre of the right panel). Galaxies at this distance are impossible to detect in visible light as their emitted radiation has been ‘redshifted’ far into the infrared.</span>
<span class="attribution"><span class="source">NASA/STScI/C. Jacobs</span></span>
</figcaption>
</figure>
<p>Although this galaxy – the small, red blob in the right image – is not among the most spectacularly picturesque our universe has to offer, it is just as interesting scientifically.</p>
<p>This snapshot is from when the universe was a mere 350 million years old, making this among the very first galaxies ever to have formed. Understanding the details of how such galaxies grow and merge to create galaxies like our own Milky Way 13 billion years later is a key question, and one with many remaining mysteries, making discoveries like this highly sought after.</p>
<p>It is also a view only the JWST can achieve. Astronomers did not know quite what to expect; an image of this galaxy taken with Hubble would appear blank, as the light of the galaxy is stretched far into the infrared by the expansion of the universe. </p>
<h2>10. This giant mosaic of Abell 2744</h2>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/499261/original/file-20221206-12-pevvt.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An irregularly shaped image of hundreds of glowing dots on a dark background" src="https://images.theconversation.com/files/499261/original/file-20221206-12-pevvt.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/499261/original/file-20221206-12-pevvt.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=422&fit=crop&dpr=1 600w, https://images.theconversation.com/files/499261/original/file-20221206-12-pevvt.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=422&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/499261/original/file-20221206-12-pevvt.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=422&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/499261/original/file-20221206-12-pevvt.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=530&fit=crop&dpr=1 754w, https://images.theconversation.com/files/499261/original/file-20221206-12-pevvt.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=530&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/499261/original/file-20221206-12-pevvt.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=530&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An image of the galaxy cluster Abell 2744 created by combining many different JWST exposures. In this tiny part of the sky (a fraction of a full Moon) almost every one of the thousands of objects shown is a distant galaxy.</span>
<span class="attribution"><span class="source">Lukas Furtak (Ben-Gurion University of the Negev) from images from the GLASS/UNCOVER teams</span></span>
</figcaption>
</figure>
<p>This image (<a href="https://images.theconversation.com/files/499261/original/file-20221206-12-pevvt.jpeg">click here for full view</a>) is a mosaic (many individual images stitched together) centred on the giant Abell 2744 galaxy cluster, colloquially known as “Pandora’s Cluster”. The sheer number and variety of sources that the JWST can detect is mind boggling; with the exception of a handful of foreground stars, every spot of light <em>represents an entire galaxy</em>.</p>
<p>In a patch of dark sky no larger than a fraction of the full Moon there are umpteen thousands of galaxies, really bringing home the sheer scale of the universe we inhabit. Professional and amateur astronomers alike can spend hours scouring this image for oddities and mysteries.</p>
<p>Over the coming years, JWST’s ability to look so deep and far back into the universe will allow us to answer many questions about how we came to be. Just as exciting are the discoveries and questions we can not yet foresee. When you peel back the veil of time as only this new telescope can, these unknown unknowns are certain to be fascinating.</p>
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<strong>
Read more:
<a href="https://theconversation.com/how-the-james-webb-space-telescope-has-revealed-a-surprisingly-bright-complex-and-element-filled-early-universe-podcast-196649">How the James Webb Space Telescope has revealed a surprisingly bright, complex and element-filled early universe – podcast</a>
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<img src="https://counter.theconversation.com/content/194739/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Colin Jacobs' work is funded by the Australian Research Council grant FL180100060. He is a member of the Australian Greens.</span></em></p><p class="fine-print"><em><span>Karl Glazebrook receives funding for JWST research from the Australian Research Council through Laureate Fellowship FL180100060.</span></em></p>A year on since the historic launch of the most powerful infrared telescope in human history, we admire and explore some of the best images it delivered in 2022.Colin Jacobs, Postdoctoral Researcher in Astrophysics, Swinburne University of TechnologyKarl Glazebrook, ARC Laureate Fellow & Distinguished Professor, Centre for Astrophysics & Supercomputing, Swinburne University of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1867382022-07-13T06:25:20Z2022-07-13T06:25:20ZTwo experts break down the James Webb Space Telescope’s first images, and explain what we’ve already learnt<figure><img src="https://images.theconversation.com/files/473807/original/file-20220713-24-63h22t.jpg?ixlib=rb-1.1.0&rect=209%2C63%2C5852%2C3917&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">NASA/JWST</span></span></figcaption></figure><p>Today we saw the release of the <a href="https://www.nasa.gov/webbfirstimages">first batch of images</a> taken by the James Webb Space Telescope. This is something we have both been waiting on for nearly 25 years. Back in those days, we were analysing the <a href="https://theconversation.com/hubble-webb-and-the-search-for-first-light-galaxies-5116">first Hubble images</a> of the distant universe, and the details they revealed were shocking compared to anything we’d seen in ground-based images. </p>
<p>It seems the bar has been raised once again, and Webb is set to herald a new age for astronomy and space research. Its large mirror helps it produce images that are two to three times sharper than Hubble’s, and which go much deeper into space (which means it can see fainter sources). </p>
<p>Webb can also see far redder infrared wavelengths, opening up a new view on the universe. This is especially important to study the early universe due to “<a href="https://astronomy.swin.edu.au/cosmos/c/cosmological+redshift">cosmological redshift</a>”, a process which refers to the stretching of light (with the expansion of the universe) as it travels across cosmic space.</p>
<p>It’s also useful for studying fascinating sources such as planets going around nearby stars, and the regions where stars form.</p>
<p>We’ve written before about the tremendous technical challenges involved in the construction of Webb and its journey into orbit. Now, with the long-awaited first images in our hands, let’s take a look at what they show.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/nasas-james-webb-space-telescope-has-reached-its-destination-1-5-million-km-from-earth-heres-what-happens-next-175327">NASA's James Webb Space Telescope has reached its destination, 1.5 million km from Earth. Here's what happens next</a>
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<h2>Intense clarity</h2>
<p>In a sneak peak, US President Joe Biden presented the very first image of Webb’s “deep field”. This is the massive galaxy cluster SMACS-0723 that contains thousands of galaxies clustered around a central super-bright galaxy squatting at the centre. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/473788/original/file-20220713-12-smix23.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/473788/original/file-20220713-12-smix23.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/473788/original/file-20220713-12-smix23.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=612&fit=crop&dpr=1 600w, https://images.theconversation.com/files/473788/original/file-20220713-12-smix23.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=612&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/473788/original/file-20220713-12-smix23.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=612&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/473788/original/file-20220713-12-smix23.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=769&fit=crop&dpr=1 754w, https://images.theconversation.com/files/473788/original/file-20220713-12-smix23.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=769&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/473788/original/file-20220713-12-smix23.jpeg?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">The giant southern cluster SMACS 0723 was captured by Webb.</span>
<span class="attribution"><span class="source">NASA, ESA, CSA, and STScI</span></span>
</figcaption>
</figure>
<p>You’ll immediately notice the many elongated arcs, representing background galaxies which have been <a href="https://esahubble.org/wordbank/gravitational-lensing/">“gravitationally lensed”</a> as a result of the cluster’s mass. In other words, the huge forces of gravity at play have resulted in the light from the galaxies becoming distorted (stretched) and amplified, providing a highly enhanced image of the distant universe.</p>
<p>The clarity is astonishing, especially in terms of the structure of the lensed images. Here’s a zoomed-in look at one tiny region, compared with an image of similar exposure time from Hubble:</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/473797/original/file-20220713-16-1j48rf.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/473797/original/file-20220713-16-1j48rf.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/473797/original/file-20220713-16-1j48rf.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=196&fit=crop&dpr=1 600w, https://images.theconversation.com/files/473797/original/file-20220713-16-1j48rf.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=196&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/473797/original/file-20220713-16-1j48rf.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=196&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/473797/original/file-20220713-16-1j48rf.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=247&fit=crop&dpr=1 754w, https://images.theconversation.com/files/473797/original/file-20220713-16-1j48rf.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=247&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/473797/original/file-20220713-16-1j48rf.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=247&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 comparison of Webb (left) and Hubble (right) in their view of the same region. This is a zoomed-in area of the Webb deep field.</span>
<span class="attribution"><span class="source">Adapted from images by NASA, ESA, CSA, and STScI</span></span>
</figcaption>
</figure>
<p>The enlarged images above portray a region in the deep field containing a spiral galaxy astronomers have affectionately been calling “The Slug”. It’s located several times further than the SMACS-0723 cluster.</p>
<p>But our eyes were drawn more to the very thin arc just above (marked with arrows). This little sliver demonstrates Webb’s power. This arc was barely detected by Hubble, but Webb sees the “beads on a string” clearly. They are likely individual star clusters in the extremely distant, tiny galaxy. </p>
<p>We can see similarly amazing details <a href="https://twitter.com/karlglazebrook/status/1546827643370508289">all over the deep field</a>. For point-like objects, Webb is expected to be beyond 100 times more sensitive than Hubble, and this definitely demonstrates that. </p>
<p>The field is also scattered with some faint red objects, which are already attracting attention by experts. Some of these could potentially be the most distant galaxies, where the light has taken the longest to reach us. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1546838181248929794"}"></div></p>
<h2>Revealing hidden elements</h2>
<p>Webb is also capable of extremely sensitive infrared spectroscopy, where light is broken down in wavelengths to reveal the composition of an object. </p>
<p>While Hubble is very poor at this, Webb manages to do this nicely – shown below by the spectrum of the massive planet WASP 96b. Located some 1120 light-years away, this planet weighs in at about half the mass of Jupiter.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/473790/original/file-20220713-22-bno765.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/473790/original/file-20220713-22-bno765.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/473790/original/file-20220713-22-bno765.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=404&fit=crop&dpr=1 600w, https://images.theconversation.com/files/473790/original/file-20220713-22-bno765.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=404&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/473790/original/file-20220713-22-bno765.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=404&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/473790/original/file-20220713-22-bno765.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=507&fit=crop&dpr=1 754w, https://images.theconversation.com/files/473790/original/file-20220713-22-bno765.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=507&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/473790/original/file-20220713-22-bno765.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=507&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Webb captured the spectrum of exoplanet WASP-96b, a hot gas giant.</span>
<span class="attribution"><span class="source"> NASA, ESA, CSA, and STScI</span></span>
</figcaption>
</figure>
<p>The dips in the spectrum reveal the presence of water vapour in the planet’s atmosphere. Now, WASP 69b is unlikely to harbour life because of its proximity to its parent star. Yet this demonstration is very exciting since the same method can be applied to the 5,000 or so other known exoplanets.</p>
<p>With spectroscopy, we’ll eventually be able to detect potential signatures of life such as ozone and methane.</p>
<h2>Seeing dust and gas</h2>
<p>The third image is of the Southern Ring Nebula, about 2,000 light-years away in the Milky Way. This image shows off Webb’s mid-infrared capability (which is again well beyond Hubble’s range).</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/473791/original/file-20220713-12-i1b7wc.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/473791/original/file-20220713-12-i1b7wc.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/473791/original/file-20220713-12-i1b7wc.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=278&fit=crop&dpr=1 600w, https://images.theconversation.com/files/473791/original/file-20220713-12-i1b7wc.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=278&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/473791/original/file-20220713-12-i1b7wc.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=278&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/473791/original/file-20220713-12-i1b7wc.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=350&fit=crop&dpr=1 754w, https://images.theconversation.com/files/473791/original/file-20220713-12-i1b7wc.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=350&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/473791/original/file-20220713-12-i1b7wc.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 Southern Ring planetary nebula, with a near-infrared image on the left and a mid-infrared one on the right.</span>
<span class="attribution"><span class="source">NASA, ESA, CSA, and STScI</span></span>
</figcaption>
</figure>
<p>It’s a classic example of a “planetary nebula” (a misnomer since no planet is involved) in which the central star has transformed into a tiny white dwarf by blowing off its outer layer. This happens at a speed of about 15 kilometres per second, sending out rings of gas and dust. </p>
<p>The brightest star in the centre is actually a companion star, and the white dwarf is the fainter partner which can only be seen in the mid-infrared since it’s obscured by dust. The mid-infared also highlights the dust being formed in the expanding gas.</p>
<p>The fourth image below shows us Webb’s view of nearby galaxies. Here we see a famous galaxy group called Stefan’s Quintet, located about 290 million light-years away. The five galaxies are in close proximity. Four are interacting with each other and triggering abundant star formation. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/473792/original/file-20220713-14-lfmu98.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/473792/original/file-20220713-14-lfmu98.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/473792/original/file-20220713-14-lfmu98.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=575&fit=crop&dpr=1 600w, https://images.theconversation.com/files/473792/original/file-20220713-14-lfmu98.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=575&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/473792/original/file-20220713-14-lfmu98.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=575&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/473792/original/file-20220713-14-lfmu98.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=723&fit=crop&dpr=1 754w, https://images.theconversation.com/files/473792/original/file-20220713-14-lfmu98.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=723&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/473792/original/file-20220713-14-lfmu98.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=723&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Stephan’s Quintet is a compact group of interacting galaxies.</span>
<span class="attribution"><span class="source">NASA, ESA, CSA, and STScI</span></span>
</figcaption>
</figure>
<p>The red streaks and clumps show the location of new star formation via the associated dust. The detail of the dust distribution and the tug-of-war taking place between the galaxies leaps out from the image. And the mid-infrared reveals light from a supermassive black hole in the centre of the top galaxy. </p>
<p>What also stands out is the vast sea of distant galaxies in the background. We expect to see this in every Webb image, even when Webb points to sources within the Milky Way. That’s because infrared light passes through dust. Webb’s infrared-detecting capabilities are so sensitive it will see right through objects within our galaxy.</p>
<p>This means distant background galaxies will be photo-bombing every Webb image. See if you can spot them in the Southern Ring and Carina images.</p>
<p>And finally, we have Webb’s homage to Hubble’s famous <a href="https://www.nasa.gov/image-feature/the-pillars-of-creation">Pillars of Creation</a> image.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/473793/original/file-20220713-18-smix23.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/473793/original/file-20220713-18-smix23.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/473793/original/file-20220713-18-smix23.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=348&fit=crop&dpr=1 600w, https://images.theconversation.com/files/473793/original/file-20220713-18-smix23.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=348&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/473793/original/file-20220713-18-smix23.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=348&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/473793/original/file-20220713-18-smix23.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=437&fit=crop&dpr=1 754w, https://images.theconversation.com/files/473793/original/file-20220713-18-smix23.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=437&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/473793/original/file-20220713-18-smix23.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">The Carina Nebula, a cosmic nursery cocooned in gas and dust.</span>
<span class="attribution"><span class="source">NASA, ESA, CSA, and STScI</span></span>
</figcaption>
</figure>
<p>This infrared view shows the Carina Nebula, a stellar nursery of gas and dust 7,600 light-years away where new stars are forming and destroying their birth cloud. </p>
<p>The image is extremely complex, and the intricate swirls of dust, gas and young stars are jaw-dropping. It will probably take astronomers many years of hard work to figure out exactly what’s going on here. </p>
<p>Just this handful of preview images, a few days work for Webb, have given astronomers tremendous amounts of new data that will drive years of research. And that’s just the beginning.</p><img src="https://counter.theconversation.com/content/186738/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Karl Glazebrook receives funding from the Australian Research Council for research with the James Webb Space Telescope.</span></em></p><p class="fine-print"><em><span>Simon Driver 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>Through direct comparison with images from Hubble, you can start to see the exquisite detail and clarity Webb provides.Karl Glazebrook, ARC Laureate Fellow & Distinguished Professor, Centre for Astrophysics & Supercomputing, Swinburne University of TechnologySimon Driver, Professor of Astrophysics at the International Centre for Radio Astronomy Research, The University of Western AustraliaLicensed 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/1831392022-05-17T15:29:21Z2022-05-17T15:29:21ZAfrican scientists and technology could drive future black hole discoveries<figure><img src="https://images.theconversation.com/files/463262/original/file-20220516-11-yif57t.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Milky Way above a single MeerKAT antenna in the Northern Cape Province of South Africa. Inset: EHT image of the Milky Way black hole. </span> <span class="attribution"><span class="source">SARAO, EHT</span></span></figcaption></figure><p>Astronomers <a href="https://eventhorizontelescope.org/blog/astronomers-reveal-first-image-black-hole-heart-our-galaxy">have revealed</a> the first image of the black hole at the centre of our galaxy, the Milky Way. The image was produced by the Event Horizon Telescope (EHT) Collaboration, an international team made up of over 300 scientists on five continents – including Africa.</p>
<p>Black holes were predicted by Albert Einstein’s <a href="https://www.space.com/17661-theory-general-relativity.html">General Theory of Relativity</a> over a century ago. They are regions of space so dense that nothing, including light, can escape. Their boundary is known as the event horizon, which marks the point of no return. That’s just one of the reasons these objects are hidden from our eyes. The other is that they are exceedingly small, when placed in their cosmic context. If our Milky Way galaxy were the size of a soccer field, its black hole event horizon would be a million times smaller than a pin prick at centrefield.</p>
<p>How, then, can one photograph them? Our team did so by capturing light from the hot swirling gas in the immediate vicinity of the black hole. This light, with a wavelength of 1 millimetre, is recorded by a global network of antennas that form a single, Earth-sized virtual telescope. </p>
<p>The light looks rather like a ring, a characteristic signature that is the direct consequence of two key processes. First, the black hole is so dense that it bends the path of light near it. Second, it captures light that strays too close to the event horizon. The combined effect produces a so-called black hole shadow - a brightened ring surrounding a distinct deficit of light centred on the black hole. In the case of our Milky Way black hole, this ring has the apparent size of a doughnut on the moon, requiring an extraordinary engineering effort to bring it into focus. </p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/how-we-captured-first-image-of-the-supermassive-black-hole-at-centre-of-the-milky-way-183010">How we captured first image of the supermassive black hole at centre of the Milky Way</a>
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</p>
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<p>The unveiling of an image of our black hole, <a href="https://theconversation.com/say-hello-to-sagittarius-a-the-black-hole-at-the-center-of-the-milky-way-galaxy-183008">Sagittarius A*</a>, is not just a massive moment for science. It could also be an important catalyst for diversifying African astrophysics research using existing strengths. We were the only two of more than 300 EHT team members based on the African continent. The continent doesn’t host any EHT telescopes – we were brought on board because of expertise we’ve developed in preparation for the world’s largest radio telescope, the <a href="https://www.skatelescope.org/">Square Kilometre Array</a> (SKA), to be co-hosted by South Africa and Australia.</p>
<h2>Why the image is important</h2>
<p>This is not the first time a black hole image has captured people’s attention. We were also members of the team that captured the <a href="https://www.nationalgeographic.com/science/article/first-picture-black-hole-revealed-m87-event-horizon-telescope-astrophysics">first ever image of a black hole in 2019</a> (this one is at the centre of a different galaxy, Messier 87, which is 55 million light years away). <a href="https://www.capjournal.org/issues/26/26_11.pdf">It has been estimated</a> that more than 4.5 billion people saw that image. Sagittarius A* has also dominated headlines and captured people’s imaginations.</p>
<p>But there’s more to this result than just an incredible image. A plethora of rich scientific results has been described in <a href="https://iopscience.iop.org/journal/2041-8205/page/Focus_on_First_Sgr_A_Results">ten publications</a> by the team. Here are three of our primary highlights.</p>
<p>First, the image is a remarkable validation of Einstein’s General Theory of Relativity. The EHT has now imaged two black holes with masses that differ by a factor of over 1000. Despite the dramatic difference in mass, the measured size and shape are consistent with theoretical predictions.</p>
<p>Second, we have now imaged black holes with very different environments. A wealth of prior research over the past two or three decades shows strong empirical evidence that galaxies and their black holes co-evolve over cosmic time, despite their completely disparate sizes. By zooming into the event horizon of black holes in giant galaxies like M87, as well as more typical galaxies like our own Milky Way, we learn more about how this seemingly implausible relationship between the black hole and its host galaxy plays out. </p>
<p>Third, the image provides us with new insights on the central black hole in our own galactic home. It is the nearest such beast to Earth, so it provides a unique laboratory to understand this interplay – not unlike scrutinising a tree in your own garden to better understand the forests on the distant horizon. </p>
<h2>Southern Africa’s geographic advantage</h2>
<p>We are proud to be part of the team that produced the first black hole images. In future, we believe South Africa, and the African continent more broadly (including <a href="https://www.ru.nl/astrophysics/radboud-radio-lab/projects/africa-millimetre-telescope-amt/">a joint Dutch-Namibian initiative</a>), could play a critical role in making the first black hole movies. </p>
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<p>
<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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</em>
</p>
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<p>As has been the case with the country’s key role in paleoanthropology, there are contributions to global astronomy that can only be made from South African soil. Sagittarius A* lies in the southern sky, passing directly above South Africa. That is a major reason why this image of the Milky Way’s centre, taken by the MeerKAT (a precursor to the SKA) is the best there is. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/463268/original/file-20220516-25-mk91ce.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/463268/original/file-20220516-25-mk91ce.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/463268/original/file-20220516-25-mk91ce.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=393&fit=crop&dpr=1 600w, https://images.theconversation.com/files/463268/original/file-20220516-25-mk91ce.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=393&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/463268/original/file-20220516-25-mk91ce.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=393&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/463268/original/file-20220516-25-mk91ce.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=494&fit=crop&dpr=1 754w, https://images.theconversation.com/files/463268/original/file-20220516-25-mk91ce.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=494&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/463268/original/file-20220516-25-mk91ce.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=494&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 MeerKAT Galactic Centre image (top). Predicted snapshot imaging performance (bottom middle), based on a simulated black hole movie (bottom left), using an African-enhanced EHT array (bottom right).</span>
<span class="attribution"><span class="source">Heywood et al. (2022) / SARAO, M. Johnson (Harvard & Smithsonian)</span></span>
</figcaption>
</figure>
<p>South Africa also has well-established infrastructure at its astronomical sites, which are protected by legislation. And it has world-class engineers at the forefront of their craft. This makes for low-cost, high-performance telescopes delivered on time and to budget. </p>
<p>New technology is also on our side: a cutting-edge simultaneous multi-frequency receiver design, pioneered by our Korean colleagues, means that EHT sites no longer need to be the most pristine, high-altitude locations on Earth.</p>
<p>All the elements are in place for a dramatic increase in the number of young Africans who participate in this new era of black hole imaging and precision tests of gravity. In the coming years, we hope to be writing about findings that couldn’t have been made without technology on South African soil, as well as African scientists leading high-impact, high-visibility EHT science in synergy with our multi-wavelength astronomy and high-energy astrophysics programmes.</p><img src="https://counter.theconversation.com/content/183139/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Roger Deane receives research funding from the South African Radio Astronomy Observatory, which is a facility of the National Research Foundation (NRF), an agency of the Department of Science and Innovation (DSI) of South Africa. </span></em></p><p class="fine-print"><em><span>Iniyan Natarajan receives research funding from the South African Radio Astronomy Observatory, which is a facility of the National Research Foundation (NRF), an agency of the Department of Science and Innovation (DSI) of South Africa.</span></em></p>Sagittarius A* lies in the southern sky, passing directly above South Africa.Roger Deane, Director: Wits Centre for Astrophysics; SKA Chair in Radio Astronomy, University of the WitwatersrandIniyan Natarajan, Postdoctoral Research Fellow, Wits Centre for Astrophysics, University of the WitwatersrandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1783152022-03-17T04:15:21Z2022-03-17T04:15:21ZThe James Webb Space Telescope has taken its first aligned image of a star. Here’s how it was done<figure><img src="https://images.theconversation.com/files/452681/original/file-20220317-8345-4q9ile.png?ixlib=rb-1.1.0&rect=203%2C415%2C5225%2C3011&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">NASA</span></span></figcaption></figure><p>In a huge milestone, the James Webb Space Telescope (JWST) has finally <a href="https://www.nasa.gov/press-release/nasa-s-webb-reaches-alignment-milestone-optics-working-successfully">been aligned</a> to produce the first unified image of a single star.</p>
<p>Most <a href="https://spaceplace.nasa.gov/telescopes/en/">traditional telescopes</a> these days (like one you might have in your backyard) have a single primary mirror that collects distant light from stars. But the JWST has 18 mirrors! These had to be aligned extremely precisely to capture the image NASA released today. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/452628/original/file-20220316-8637-1fgidb5.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/452628/original/file-20220316-8637-1fgidb5.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/452628/original/file-20220316-8637-1fgidb5.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/452628/original/file-20220316-8637-1fgidb5.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/452628/original/file-20220316-8637-1fgidb5.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/452628/original/file-20220316-8637-1fgidb5.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/452628/original/file-20220316-8637-1fgidb5.gif?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">This gif shows the several intermediary images of stars used for the crucial JWST mirror alignment process.</span>
<span class="attribution"><span class="source">NASA/Twitter</span></span>
</figcaption>
</figure>
<h2>The challenge with JWST</h2>
<p>The JWST is the largest telescope humans have ever sent into space. It’s so big that none of our rockets can carry it when fully extended. As such, it was designed to be neatly folded to fit inside the cargo hold atop an <a href="https://www.arianespace.com/wp-content/uploads/2020/06/Arianespace_Brochure_Ariane5_Sept2019.pdf">Ariane 5 launch vehicle</a>. </p>
<p>The telescope uses segmented mirror technology. This technology has been in use for a few decades now, by some of the largest optical telescopes in the world, including the <a href="https://www.keckobservatory.org">Keck Observatory</a> in Hawaii (which has two 10m-diameter mirrors, each made of 36 hexagonal segments). </p>
<p>The main challenge with the JWST was being able to unfold it to its fully extended form in space, under extreme conditions of heat and cold, and with no human assistance. </p>
<p>This process began in January. Once the mirror segments were unfolded, they had to be aligned so all 18 combined to form a single 6.5m-diameter curved mirror.</p>
<p>The JWST has now completed this <a href="https://blogs.nasa.gov/webb/2022/02/03/photons-incoming-webb-team-begins-aligning-the-telescope/">alignment process</a>, giving us the first unified image. The image was taken using the <a href="https://jwst-docs.stsci.edu/jwst-near-infrared-camera">near infrared camera (NIRCam)</a>, one of the telescope’s <a href="https://www.stsci.edu/jwst/instrumentation/instruments">four key science instruments</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/452683/original/file-20220317-8368-1ec7r1m.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Close-up view of the NIRCam instrument" src="https://images.theconversation.com/files/452683/original/file-20220317-8368-1ec7r1m.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/452683/original/file-20220317-8368-1ec7r1m.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=429&fit=crop&dpr=1 600w, https://images.theconversation.com/files/452683/original/file-20220317-8368-1ec7r1m.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=429&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/452683/original/file-20220317-8368-1ec7r1m.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=429&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/452683/original/file-20220317-8368-1ec7r1m.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=539&fit=crop&dpr=1 754w, https://images.theconversation.com/files/452683/original/file-20220317-8368-1ec7r1m.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=539&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/452683/original/file-20220317-8368-1ec7r1m.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=539&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 is the optical system that captures images on the James Webb Space Telescope.</span>
<span class="attribution"><span class="source">NASA</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>But how was this done?</h2>
<p>There are seven <a href="https://www.flickr.com/photos/nasawebbtelescope/13291045605/">small motors</a> fixed behind each of the JWST’s 18 slightly curved hexagonal mirrors. Their purpose is to move and reshape the curvature of each segment so that all 18 can act as a single large mirror. </p>
<p>Six of these motors are grouped in pairs, equally distanced and located around each mirror segment. These are used to move the mirror.</p>
<p>The seventh motor is at the centre and is connected to the mirror’s six corners with struts. This motor can adjust the tension of the struts to optimise the curvature of that mirror segment.</p>
<p>The motors can move the mirrors very precisely, to within about 1/10,000th of the diameter of a human hair. This precision (to within a fraction of a wavelength of light) is important for obtaining high quality images from the telescope.</p>
<p>NASA scientists used a mathematical analysis called “<a href="https://ui.adsabs.harvard.edu/abs/2006SPIE.6265E..11D/abstract">phase retrieval</a>” to study how the movement of each individual segment changed the sharpness of the final image. </p>
<p>Once they had this information, there were two crucial tasks to complete before the segments could function as a single, monolithic mirror: coarse alignment and fine alignment. </p>
<h2>Coarse and fine alignment</h2>
<p>In coarse alignment, the mirror segments were moved vertically (up and down) until they aligned to form one giant mirror. However, there were still minute alignment errors that needed to be corrected to obtain the best possible image. </p>
<p>This is where the fine alignment happens. In this process, rather than moving the mirror segments, the small optics inside NIRCam are moved instead. </p>
<p>When the telescope is pointed at a star, the light from the star first hits the primary mirror, in which the individual segments are now aligned reasonably well.</p>
<p>The light then continues its path through the secondary and tertiary mirrors inside the telescope and enters the NIRCam instrument. During the fine alignment, the optics inside NIRCam are very carefully adjusted until the star is completely in focus. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/452690/original/file-20220317-8303-olr076.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/452690/original/file-20220317-8303-olr076.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/452690/original/file-20220317-8303-olr076.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=382&fit=crop&dpr=1 600w, https://images.theconversation.com/files/452690/original/file-20220317-8303-olr076.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=382&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/452690/original/file-20220317-8303-olr076.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=382&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/452690/original/file-20220317-8303-olr076.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=480&fit=crop&dpr=1 754w, https://images.theconversation.com/files/452690/original/file-20220317-8303-olr076.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=480&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/452690/original/file-20220317-8303-olr076.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=480&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">There are four different types of mirrors on the Webb telescope: primary mirror segments, the secondary mirror, tertiary mirror and the fine steering mirror.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/nasawebbtelescope/5890960025/in/album-72157658888594928/">NASA/Ball Aerospace/Tinsley</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>The coarse and fine alignment steps are both repeated until the sharpest image can be obtained. The image released by NASA this week shows how a star looks when these steps are completed. </p>
<p>Prior to this, NASA released a “stacked” image (likely of the same star) back in February. </p>
<p>For this, each of the individual mirror segments were fine-tuned to create <a href="https://blogs.nasa.gov/webb/wp-content/uploads/sites/326/2022/02/SegmentAlignment.gif">18 sharp images of the star</a>, but each from a slightly different vantage point. The 18 images were then stacked to produce the image below. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/452402/original/file-20220316-15-1x1dxvw.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Stacked image of a star taken by the James Webb Space Telescope" src="https://images.theconversation.com/files/452402/original/file-20220316-15-1x1dxvw.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/452402/original/file-20220316-15-1x1dxvw.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/452402/original/file-20220316-15-1x1dxvw.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/452402/original/file-20220316-15-1x1dxvw.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/452402/original/file-20220316-15-1x1dxvw.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/452402/original/file-20220316-15-1x1dxvw.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/452402/original/file-20220316-15-1x1dxvw.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">NASA scientists stacked the 18 individual images captured by the primary mirror segments to create a stacked image.</span>
<span class="attribution"><a class="source" href="https://blogs.nasa.gov/webb/wp-content/uploads/sites/326/2022/02/PostImageStacking.jpeg">NASA</a></span>
</figcaption>
</figure>
<h2>The next steps</h2>
<p>While the successful testing of the NIRCam is a breakthrough for the JWST, there are many more steps to be completed before it can fulfil its potential. </p>
<p>Next NASA will look at how the other instruments perform with images of stars, and do further fine tuning to the optics in those instruments. After this, the instrument commissioning phase will start. Apart from NIRCam, there are three other instruments on board the JWST: <a href="https://jwst-docs.stsci.edu/jwst-near-infrared-spectrograph">NIRSpec</a>, <a href="https://jwst-docs.stsci.edu/jwst-near-infrared-imager-and-slitless-spectrograph">NIRISS</a>, and <a href="https://jwst-docs.stsci.edu/jwst-mid-infrared-instrument">MIRI</a>. </p>
<p>While NIRCam will primarily provide images of the Universe over the near-infrared part of the electromagnetic spectrum, NIRSpec can split that light to study different signatures (variations in the properties of the incoming light).</p>
<p>NIRISS will provide similar functionality to NIRCam, while MIRI will look at the Universe at much higher wavelengths (reaching the mid infrared range).</p>
<p>All the instruments will be brought to their working temperatures and tested. Some initial steps have already begun and all indications so far are good. Many of the steps also have redundancies built into them, which means if a system should fail, there will be another way to achieve the same objective.</p>
<p>You can keep up to date with the JWST’s activities <a href="https://www.jwst.nasa.gov/content/webbLaunch/whereIsWebb.html">online</a>.</p>
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Read more:
<a href="https://theconversation.com/nasas-james-webb-space-telescope-has-reached-its-destination-1-5-million-km-from-earth-heres-what-happens-next-175327">NASA's James Webb Space Telescope has reached its destination, 1.5 million km from Earth. Here's what happens next</a>
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<img src="https://counter.theconversation.com/content/178315/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Themiya Nanayakkara is affiliated with the James Webb Australian Data Centre hosted at the Swinburne University of Technology. </span></em></p>The telescopes primary mirror segments are now working together to provide a single, sharp image.Themiya Nanayakkara, Chief Astronomer at the James Webb Australian Data Centre, Swinburne University of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1527772021-01-12T15:07:36Z2021-01-12T15:07:36ZSouth African astronomy has a long, rich history of discovery – and a promising future<figure><img src="https://images.theconversation.com/files/377956/original/file-20210111-23-12bfk2d.jpg?ixlib=rb-1.1.0&rect=4%2C492%2C2748%2C1655&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Southern African Large Telescope has been a key part of South Africa's astronomical contributions.</span> <span class="attribution"><span class="source">SAAO</span></span></figcaption></figure><p>The <a href="https://www.saao.ac.za/">South African Astronomical Observatory</a> in Cape Town is the oldest permanent observatory in the southern hemisphere: it turned 200 in 2020. </p>
<p>This observatory is a fundamental part of South Africa’s long history of astronomical research, which began when French academic <a href="https://academic.oup.com/astrogeo/article/43/2/2.25/281196">Nicolas-Louis de La Caille</a> visited Cape Town from 1751 to 1753. He undertook a careful examination of every square degree of the southern sky. This resulted in the first comprehensive sky survey ever made, in either hemisphere.</p>
<p>The Royal Observatory, Cape Town of Good Hope (today the South African Astronomical Observatory) was established in 1820. It became – and remained for 150 years – the most important source of star positions in the southern hemisphere sky. This was in terms of both accuracy and the number of measurements made. In the years that followed its foundation, the observatory’s laborious work led to important scientific discoveries. </p>
<p>Cape astronomers were responsible for, among other things, the first measurement of the distance to a star; the first photographic sky survey and the accurate measurement of the distance to the sun. They were at the forefront of developments in stellar spectroscopy. This is the detailed analysis of a star’s light to find out its composition and movement towards or away from the sun. They also determined the shape of the earth in the southern hemisphere and conducted the first accurate country-wide survey measurements of southern Africa. </p>
<h2>Measuring stellar distances</h2>
<p>In 1543 the mathematician and astronomer <a href="https://plato.stanford.edu/entries/copernicus/">Nicolaus Copernicus</a> asserted that the earth orbits the sun. This meant that people should be able to observe the apparent shift in the position of the nearest stars from different points in the earth’s orbit. But that had not been observed in the centuries that followed. The reason was, of course, that even the nearest stars are incredibly far away and the effect being looked for is very small. </p>
<p>When the Royal Observatory was founded in 1820, it was equipped with the most accurate star position measuring devices available. Eleven years later Thomas Henderson used those devices to make the first believable measurements of this effect, known as “<a href="https://www.space.com/30417-parallax.html">parallax</a>”. By observing the angular “movement” of Alpha Centauri – still the second-closest star known to us – and knowing also the size of the earth’s orbit, this gave the distance to the star by simple trigonometry. </p>
<p>A different technology, photography, would lead to more important astronomical discoveries at the Cape. All observatories in the 19th century made precise observations of star positions one by one and published catalogues of these. In 1882 the head of the Royal Observatory, David Gill, was surprised to receive a letter from a Mr Simpson, an amateur photographer in Aberdeen, a town elsewhere in the Cape. </p>
<p>Simpson had managed to photograph a bright comet that had just appeared. His photographic plates were sensitive enough to register stars in the background. This led to a “lightbulb” moment for Gill: he realised that the positions of stars could now be recorded in quantity on a permanent medium, more reliably than any visual observer could ever hope to do. </p>
<p>So he set up a special photographic telescope using the largest lens that he could find and set about making the first photographic star catalogue. This was called the <a href="http://adsabs.harvard.edu/full/1896AnCap...3....1G">Cape Photographic Durchmusterung</a> after its much more laboriously compiled northern hemisphere equivalent, put together in Bonn, Germany. </p>
<p>But it wasn’t just Cape Town that hosted an important astronomical site.</p>
<p>In 1903, the <a href="https://www.saasta.ac.za/johannesburg-observatory/">Johannesburg Observatory</a> was established. It achieved its greatest success in 1915 when its director, Robert Innes, discovered a very faint star near Alpha Centauri. </p>
<p>On various grounds he claimed it to be the nearest star to Earth; it took many years of investigation before this could be verified. The new discovery was named “Proxima Centauri”, meaning the nearest in the constellation Centaurus. Not only was it the nearest star but at that time of discovery it was the least luminous star ever discovered. Other dimmer stars have been found since, but Proxima still retains its nearest star status and its distance has been thoroughly verified from space satellites. </p>
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Read more:
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<h2>Doubling the size of the Universe</h2>
<p>In 1948 the private Radcliffe Foundation in the United Kingdom set up in Pretoria what was for a time the largest telescope in the southern hemisphere and joint fourth largest in the world. This is a title currently held by the <a href="https://www.salt.ac.za/">Southern African Large Telescope</a>. </p>
<p>Early on in the Radcliffe’s existence the then director, David Thackeray, and his colleague Adriaan Wesselink discovered in our neighbouring galaxy, the Large Magellanic Cloud, a number of RR Lyrae variable stars that astronomers using smaller telescopes could not detect. These are stars that change their brightness in a well-defined manner over a cycle of a few days and whose average “wattage” is completely predictable.</p>
<p>By measuring the Magellanic Cloud stars’ average apparent brightnesses and comparing them to other RR Lyrae stars at known distances they determined that the cosmic distance scale originally published two decades before by Edwin Hubble and others was underestimated by about a factor of two. In effect, they doubled the size of the Universe. This result was announced to great acclaim at the triennial meeting of the <a href="http://adsabs.harvard.edu/full/1952JRASC..46..217D">International Astronomical Union in 1952</a>. </p>
<h2>More to come</h2>
<p>Today South African astronomy remains at the forefront of many initiatives and discoveries. It has become a leader in the field of radio astronomy with the MeerKAT telescope near Carnarvon and will within a decade be the host of an international project, the <a href="https://www.skatelescope.org/">Square Kilometre Array</a>.</p>
<p><em>This article is adapted from <a href="https://www.nrf.ac.za/sites/default/files/documents/04%20NRF%20SMM%20V3%20Issue3%20Highlights%20of%20Astronomy%20in%20South%20Africa%20Before%201972.pdf">a piece</a> that initially appeared in the South African National Research Foundation’s Science Matters Magazine.</em></p><img src="https://counter.theconversation.com/content/152777/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ian Glass 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>Cape astronomers were responsible for, among other things, the first measurement of the distance to a star; the first photographic sky survey and the accurate measurement of the distance to the sun.Ian Glass, Associate Research Astronomer, South African Astronomical ObservatoryLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1513742020-12-16T03:42:56Z2020-12-16T03:42:56ZThe best gift in the galaxy: an astronomer’s guide to buying a home telescope<figure><img src="https://images.theconversation.com/files/375266/original/file-20201215-23-1s0sicj.jpg?ixlib=rb-1.1.0&rect=94%2C114%2C4398%2C2411&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Since time immemorial, humans have been fascinated by the night sky.</p>
<p>Our relationship with it was forever changed in the early 1600s, when <a href="https://www.loc.gov/collections/finding-our-place-in-the-cosmos-with-carl-sagan/articles-and-essays/modeling-the-cosmos/galileo-and-the-telescope">Galileo Galilei</a> raised a small hand-held telescope to the sky and became the first person to see Jupiter’s moons and Saturn’s rings.</p>
<p>Optical telescopes today range from pocket telescopes just a few inches long, to the colossal <a href="https://www.tmt.org/">Thirty Meter Telescope</a> being built in Hawaii (which will weigh more than 1,400 tonnes).</p>
<p>There are even bigger arrays of telescopes that observe in radio wavelengths, such as the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope.</p>
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Read more:
<a href="https://theconversation.com/weve-mapped-a-million-previously-undiscovered-galaxies-beyond-the-milky-way-take-the-virtual-tour-here-148442">We've mapped a million previously undiscovered galaxies beyond the Milky Way. Take the virtual tour here.</a>
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<p>These large telescopes used for research don’t have a typical “eyepiece”. Rather, they use highly specialised computer-connected sensors that record signals from the sky.</p>
<p>The good news, however, is there are plenty of telescopes in more manageable sizes which you can use at home to observe moons, gas giant rings and maybe even deep sky objects such as nebulae or the Andromeda galaxy.</p>
<p>But before buying a home telescope, there are some points to consider. Who will be using it (other than you)? What do you want to observe? And just as important, how much are you willing to spend? </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/375273/original/file-20201215-13-4ibrm1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Andromeda Galaxy" src="https://images.theconversation.com/files/375273/original/file-20201215-13-4ibrm1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/375273/original/file-20201215-13-4ibrm1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=387&fit=crop&dpr=1 600w, https://images.theconversation.com/files/375273/original/file-20201215-13-4ibrm1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=387&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/375273/original/file-20201215-13-4ibrm1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=387&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/375273/original/file-20201215-13-4ibrm1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=487&fit=crop&dpr=1 754w, https://images.theconversation.com/files/375273/original/file-20201215-13-4ibrm1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=487&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/375273/original/file-20201215-13-4ibrm1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=487&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">About 2.5 million light-years away from Earth, the Andromeda galaxy is the closest major galaxy to our own, the Milky Way.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Reflectors and refractors</h2>
<p>Optical telescopes are designed to capture light emitted by stars and reflected by planets and moons. You can think of them as light-collecting buckets. The bigger they are, the more light they’ll catch. </p>
<p>This light then has to be focused to form an image. There are two types of optical telescopes available on the market today: reflectors and refractors. Reflectors use mirrors to bend incoming light; refractors use lenses.</p>
<p>Of the two options, reflectors are relatively cheaper. A few hundred dollars will buy you an instrument much larger than the refractor Galileo used. But bigger also means heavier and harder to transport. </p>
<p>Refractors are smaller, easier to transport and produce sharp images — but they’re more expensive, with a 100mm diameter telescope costing about A$500. </p>
<p>The larger the primary glass lens (where the light enters) of a refractor, the longer the whole telescope must be to focus the light rays. At the same time, the larger a lens, the harder it is to make. So there’s a limit to how big refractors can be. </p>
<p>Although refractors and reflectors are the two classic telescope designs, today there are many types of hybrid telescopes that combine elements of both. </p>
<h2>The best choice for beginners</h2>
<p>Dobsonian reflector telescopes are often recommended as a great first telescope for budding astronomers. They can be set up in as little as 20 minutes.</p>
<p>Dobsonians have very simple mounts called “Altitude-Azimuthal” mounts, which are moved by hand to a target of choice. They move in the up-and-down (altitude) and left-to-right (azimuthal) directions.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/373014/original/file-20201204-15-km97v1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/373014/original/file-20201204-15-km97v1.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=264&fit=crop&dpr=1 600w, https://images.theconversation.com/files/373014/original/file-20201204-15-km97v1.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=264&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/373014/original/file-20201204-15-km97v1.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=264&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/373014/original/file-20201204-15-km97v1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=332&fit=crop&dpr=1 754w, https://images.theconversation.com/files/373014/original/file-20201204-15-km97v1.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=332&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/373014/original/file-20201204-15-km97v1.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">
<figcaption>
<span class="caption">This diagram represents the insides of a Dobsonian reflector telescope. Light enters from the left, is reflected off a large mirror at the base of the telescope and then again reflected off a second mirror where it’s focused into the eye piece (the red X).</span>
<span class="attribution"><span class="source">Wikimedia Commons</span></span>
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<p>To get the most from your telescope, you’ll need accessories. You’d probably want some different-sized eyepieces to change the telescope’s magnification. Also, anti-glare and anti-light pollution filters are highly recommended if you live in a residential area.</p>
<p>The simplicity of Dobsonians makes them great for observing our Moon and other planets in the Solar system. A good size to start with is a 6" (150mm) Dobsonian. On average, this will set you back about A$500. </p>
<h2>Astrophotography</h2>
<p>At-home astrophotography can be done with either type of optical telescope but requires more specialised equipment. For deep-sky photos, the more you spend, the better your results will be. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/375276/original/file-20201216-17-1mfjnze.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A SkyWatcher f/5 newtonian telescope with an Equatorial GoTo mount." src="https://images.theconversation.com/files/375276/original/file-20201216-17-1mfjnze.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/375276/original/file-20201216-17-1mfjnze.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=903&fit=crop&dpr=1 600w, https://images.theconversation.com/files/375276/original/file-20201216-17-1mfjnze.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=903&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/375276/original/file-20201216-17-1mfjnze.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=903&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/375276/original/file-20201216-17-1mfjnze.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1135&fit=crop&dpr=1 754w, https://images.theconversation.com/files/375276/original/file-20201216-17-1mfjnze.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1135&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/375276/original/file-20201216-17-1mfjnze.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1135&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 telescope is attached to a GoTo equatorial mount. These can automatically point a telescope at an astronomical object the user selects. Both axes are driven by a motor.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/jonsbaglo/6033989802/">Flickr/Jon Baglo</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
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</figure>
<p>You’ll need a telescope with very good optics and a computerised “<a href="https://skywatcheraustralia.com.au/product-category/mounts/eq-mounts/eq-goto-mounts/">GoTo</a>” equatorial mount. </p>
<p>These motor-powered mounts take into account Earth’s rotation and can automatically point you to a selected object. This feature is very popular, so most major brands sell telescopes with it built in.</p>
<p>You’ll also need an external power source and accessories including a DSLR camera, camera adaptor, timer shutters and filters (depending on the type of astrophotography you want to do). Once you’re set up, your camera can capture the night sky.</p>
<p>There are many <a href="https://expertphotography.com/post-processing-astrophotography-all-you-need-to-know/">processing techniques</a> you can use after to help you get incredible compositions, as well as dedicated <a href="http://www.iceinspace.com.au/forum/index.php">online forums</a> for advice.</p>
<h2>Cosmic contributions by the public</h2>
<p>Amateur astronomers do much more than just take beautiful photos. They also help professionals. Over the decades, citizen scientists have discovered a plethora of comets and asteroids.</p>
<p>Now they’re helping with larger projects, too. One example is <a href="https://www.zooniverse.org/projects/zookeeper/galaxy-zoo/">Galaxy Zoo</a>, a crowdsourced project that asks volunteers to sort thousands of galaxies into different groups based on appearance. </p>
<p>There have been more than 60 scientific papers published as a result of these volunteering efforts. In 2017, some viewers of the ABC’s <a href="https://iview.abc.net.au/show/stargazing-live?gclid=CjwKCAiAt9z-BRBCEiwA_bWv-PdhbQOq3YQrorg6PIP6SscEaP8PqEkY_IHkPtK1Ye6pH7vk31AnXBoCv2YQAvD_BwE&gclsrc=aw.ds">Stargazing Live</a> program discovered a five-planet system orbiting a star. It became the subject of a <a href="https://arxiv.org/pdf/1801.03874.pdf">paper</a> on which they were credited as authors.</p>
<p>For anyone considering astronomy as a hobby, a good start would be to visit your local astronomical society. There are now <a href="https://astronomy.org.au/amateur/amateur-societies/australia/">more than 30</a> across Australia. </p>
<p>Society members are passionate about astronomy, often own a wide range of equipment and hold regular meetings for people with all levels of experience.</p>
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<img src="https://counter.theconversation.com/content/151374/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>There’s an extensive range of telescopes, mounts and accessories on the market, and trying to pick from it might have you seeing stars. Here’s what the experts suggest.Rebecca Allen, Swinburne Space Office Project Coordinator | Manager Swinburne Astronomy Productions, Swinburne University of TechnologyMohsen Shamohammadi, PhD researcher at the Center for Astrophysics and Supercomputing, Swinburne University of TechnologyRyan James Turner, PhD Candidate in Astrophysics, Swinburne University of TechnologyVivek Gupta, PhD Candidate in Astrophysics, Swinburne University of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1382052020-05-12T19:47:10Z2020-05-12T19:47:10ZExperts solve the mystery of a giant X-shaped galaxy, with a monster black hole as its engine<p>A team of US and South African researchers has <a href="https://arxiv.org/abs/2005.02723">published</a> highly detailed images of the largest X-shaped “radio galaxy” ever discovered – PKS 2014-55.</p>
<p>Notably, they’ve helped resolve ongoing confusion about the galaxy’s unusual shape.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/334265/original/file-20200512-175224-f1dbkn.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/334265/original/file-20200512-175224-f1dbkn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/334265/original/file-20200512-175224-f1dbkn.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=732&fit=crop&dpr=1 600w, https://images.theconversation.com/files/334265/original/file-20200512-175224-f1dbkn.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=732&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/334265/original/file-20200512-175224-f1dbkn.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=732&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/334265/original/file-20200512-175224-f1dbkn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=920&fit=crop&dpr=1 754w, https://images.theconversation.com/files/334265/original/file-20200512-175224-f1dbkn.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=920&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/334265/original/file-20200512-175224-f1dbkn.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=920&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 MeerKAT image of the giant X-shaped radio galaxy PKS 2014-55.</span>
<span class="attribution"><span class="source">Courtesy of SARAO and Bill Cotton et al/Author provided (no reuse)</span></span>
</figcaption>
</figure>
<p>The <a href="https://www.sarao.ac.za/media-releases/south-africas-meerkat-solves-mystery-of-x-galaxies/">spectacular new images</a> were taken using the 64-antenna <a href="https://www.sarao.ac.za/science-engineering/meerkat/about-meerkat/">MeerKAT</a> telescope in South Africa, by an international research team led by Bill Cotton of the US National Radio Astronomy Observatory. </p>
<h2>Zooming in on a cosmic giant</h2>
<p>Our research team also took detailed images of galaxy PKS 2014-55 last year, as part of the <a href="https://en.wikipedia.org/wiki/Evolutionary_Map_of_the_Universe">Evolutionary Map of the Universe project</a> led
by astrophysicist <a href="https://www.atnf.csiro.au/people/Ray.Norris/">Ray Norris</a>. We used CSIRO’s <a href="https://www.csiro.au/en/Research/Astronomy/ASKAP-and-the-Square-Kilometre-Array/SKA">Australian Square Kilometre Array Pathfinder</a> (ASKAP) telescope in Western Australia, which just completed its first set of pilot astronomical surveys. </p>
<p>Thanks to its innovative “radio cameras”, ASKAP can rapidly map very large areas of the sky to catalogue millions of objects emitting radio waves, from nearby supernova remnants to distant galaxies.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/334287/original/file-20200512-175219-s8xxo0.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/334287/original/file-20200512-175219-s8xxo0.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=782&fit=crop&dpr=1 600w, https://images.theconversation.com/files/334287/original/file-20200512-175219-s8xxo0.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=782&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/334287/original/file-20200512-175219-s8xxo0.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=782&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/334287/original/file-20200512-175219-s8xxo0.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=983&fit=crop&dpr=1 754w, https://images.theconversation.com/files/334287/original/file-20200512-175219-s8xxo0.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=983&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/334287/original/file-20200512-175219-s8xxo0.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=983&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Our ASKAP image of the giant X-shaped radio galaxy PKS 2014-55.</span>
<span class="attribution"><span class="source">CSIRO and the EMU team/Author provided (no reuse).</span></span>
</figcaption>
</figure>
<p>The prominent X-shape of PKS 2014-55 is made up of two pairs of <a href="https://blog.galaxyzoo.org/2014/02/03/the-curious-lives-of-radio-galaxies-part-one/">giant lobes</a> consisting of hot jets of electrons. These jets spurt outwards from a <a href="https://astronomy.swin.edu.au/cosmos/S/Supermassive+Black+Hole">supermassive black hole</a> at the galaxy’s heart.</p>
<p>The lobes emit electromagnetic radiation in the form of radio waves, which can only be detected by radio telescopes like <a href="https://www.csiro.au/en/Research/Facilities/ATNF/ASKAP">ASKAP</a>. Humans can’t see radio waves. But if we could, from Earth PKS 2014-55 would look about the same size as the Moon.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-the-universe-looks-like-when-viewed-with-radio-eyes-66381">What the universe looks like when viewed with radio eyes</a>
</strong>
</em>
</p>
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<h2>What makes a radio galaxy?</h2>
<p>Typically, <a href="https://en.wikipedia.org/wiki/Radio_galaxy">radio galaxies</a> have only one pair of lobes. One is a “jet” and the other a “counter-jet”. </p>
<p>These jets expand into the surrounding space at nearly the speed of light. They initially move in a straight line, but twist and bend into many marvellous shapes as they encounter their surroundings. </p>
<p>Centaurus A, seen below, is an example of a giant elliptical galaxy with two prominent radio lobes. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/334245/original/file-20200512-66657-3w0228.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/334245/original/file-20200512-66657-3w0228.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/334245/original/file-20200512-66657-3w0228.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=375&fit=crop&dpr=1 600w, https://images.theconversation.com/files/334245/original/file-20200512-66657-3w0228.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=375&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/334245/original/file-20200512-66657-3w0228.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=375&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/334245/original/file-20200512-66657-3w0228.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=471&fit=crop&dpr=1 754w, https://images.theconversation.com/files/334245/original/file-20200512-66657-3w0228.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=471&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/334245/original/file-20200512-66657-3w0228.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">This is an artist’s impression of the famous Centaurus A galaxy, which has two prominent radio lobes emerging from its central black hole.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/gsfc/18199018792/in/photolist-tJbJf5-2dNEVuC-29htjhd-EEHmKy-rzqGTD-95Yds7-VWRqoY-9KgqiH-qLsNuo-2hREZpf-2i9UMm7-U7eWMd-2h9dNaZ-2hcZa9a-2gGzwWB-2g2YXPm-26Twqde-2iyBv3a-D2Jexx-2dYDFz5-HbrkoD-2iKYoeb-2ecFGiW-S9bNa5-2hn6G22-2i2DXQD-2icZgrT-2f7Tk25-YW3jMi-dyhNrD-tv7Viw-2ioaJLK-2cPDMFH-2iw39Y4-Nf1txG-wTUY9C-2hmvcEb-25jHWii-2hSYj8B-dxh7au-2iRWf2C-2iw2z2v-YW3DJX-PNyWWK-fue4yp-6JLH7w-2hUxAFv-7Hb1Zt-6Zfmp7-9KgqhX">NASA Goddard Space Flight Center/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Galaxy PKS 2014-55’s <a href="https://blog.galaxyzoo.org/2014/02/04/the-curious-lives-of-radio-galaxies-part-two/">giant X-shape</a>, with two pairs of lobes emerging at very different angles, is highly unusual. </p>
<h2>What makes the lobes?</h2>
<p>To understand why having two pairs of lobes is unusual, we first need to understand what creates the lobes.</p>
<p>Nearly all big galaxies have a supermassive black hole at their centre. </p>
<p>In an active galaxy, powerful jets of charged particles can emerge from the area around the supermassive black hole. Astronomers believe these are emitted from near the poles of the black hole, which is why there are two of them, and they usually point in opposite directions.</p>
<p>When the black hole’s activity stops, the jets stop growing and the material in them flows back towards the centre. Thus, what we see as one lobe of a radio galaxy is made up of both a jet spurting out, and the backflow material.</p>
<h2>A mystery solved</h2>
<p>In the past, there were two major theories for why PKS 2014-55 has two pairs of lobes. </p>
<p>The first suggested there were actually <em>two</em> massive active black holes at the galaxy’s centre, each emitting two <a href="https://blog.galaxyzoo.org/2014/01/22/how-do-black-holes-form-jets/">powerful jets</a>. </p>
<p>The second theory suggested the supermassive black hole had undergone a <a href="https://en.wikipedia.org/wiki/Spin-flip">spin flip</a>. This is when a rotating black hole’s spin axis has a sudden change in orientation, resulting in a second pair of jets at a different angle from the first pair.</p>
<p>But the recent observations from the South African MeerKAT telescope strongly suggest a third possibility: that the two larger lobes are the fast-moving particles zooming out from the black hole, while the two smaller lobes are the backflow looping around to fall back in.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/334263/original/file-20200512-175262-bogw1y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/334263/original/file-20200512-175262-bogw1y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/334263/original/file-20200512-175262-bogw1y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=335&fit=crop&dpr=1 600w, https://images.theconversation.com/files/334263/original/file-20200512-175262-bogw1y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=335&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/334263/original/file-20200512-175262-bogw1y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=335&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/334263/original/file-20200512-175262-bogw1y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=420&fit=crop&dpr=1 754w, https://images.theconversation.com/files/334263/original/file-20200512-175262-bogw1y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=420&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/334263/original/file-20200512-175262-bogw1y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=420&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 South African Radio Astronomy Observatory’s MeerKAT telescope array consists of 64 radio dishes (pictured). Computers combine signals from these antennas to synthesise a telescope eight kilometres in diameter.</span>
<span class="attribution"><span class="source">SARAO/Author provided (no reuse)</span></span>
</figcaption>
</figure>
<p>The MeerKAT team achieved high-resolution images ten times more sensitive than our ASKAP pilot observations conducted here in Australia last year. </p>
<h2>A cosmic wonder</h2>
<p>Using <a href="https://www.csiro.au/en/Research/Facilities/ATNF/ASKAP">CSIRO’s ASKAP</a> telescope, our team observed the “purple butterfly” of PKS 2014-55 to be an enormous cosmic structure. It spans at least five million light years – about 20 times the size of our own Milky Way galaxy. </p>
<p>PKS 2014-55 is located on the outskirts of a massive cluster of galaxies known as Abell 3667. It was discovered more than 60 years ago using the <a href="https://www.atnf.csiro.au/news/newsletter/jun02/Flowering_of_Fleurs.htm">Mills Cross Telescope</a> at CSIRO’s old <a href="https://www.environment.nsw.gov.au/heritageapp/ViewHeritageItemDetails.aspx?id=2260832">Fleurs field station</a> in New South Wales. </p>
<p>The galaxy was first seen by <a href="https://www.atnf.csiro.au/people/rekers/">Ron Ekers</a> using the <a href="https://www.cambridge.org/core/journals/publications-of-the-astronomical-society-of-australia/article/parkes-interferometer/9EB4F096050C7F3A8020E3770444C1E7">Parkes Interferometer</a> in 1969.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-brain-transplant-for-one-of-australias-top-telescopes-129138">A brain transplant for one of Australia's top telescopes</a>
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</em>
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<h2>ASKAP</h2>
<p>The ASKAP telescope we used to capture PKS 2014-55 is an array of 36 radio dishes laid out in a pattern six kilometres in diameter. Together, the dishes make up a large radio telescope that uses Earth’s rotation to produce sharp images of astronomical sources near and far. </p>
<p>Each dish is 12m wide and <a href="https://www.csiro.au/en/Research/Astronomy/ASKAP-and-the-Square-Kilometre-Array/PAFs">equipped</a> with new technologies developed by CSIRO and industry partners. ASKAP is a fast survey machine, taking radio images over very wide areas of the sky. Several surveys of the entire sky are expected to start next year.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/333671/original/file-20200508-49546-110hle4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/333671/original/file-20200508-49546-110hle4.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=298&fit=crop&dpr=1 600w, https://images.theconversation.com/files/333671/original/file-20200508-49546-110hle4.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=298&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/333671/original/file-20200508-49546-110hle4.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=298&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/333671/original/file-20200508-49546-110hle4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=375&fit=crop&dpr=1 754w, https://images.theconversation.com/files/333671/original/file-20200508-49546-110hle4.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=375&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/333671/original/file-20200508-49546-110hle4.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=375&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Australian Square Kilometre Array (ASKAP) radio telescope, located in the Murchison Shire in Western Australia.</span>
</figcaption>
</figure>
<hr>
<p><em>We acknowledge the Wajarri Yamatji as the traditional owners of the Murchison Radio-astronomy Observatory site.</em></p><img src="https://counter.theconversation.com/content/138205/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Baerbel Koribalski 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>Like a cosmic butterfly in the sky, radio galaxy PKS 2014-55 was observed by CSIRO researchers with the Australian SKA Pathfinder telescope.Baerbel Koribalski, Senior research scientist, CSIROLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1307942020-01-30T03:36:39Z2020-01-30T03:36:39ZTwo satellites just avoided a head-on smash. How close did they come to disaster?<figure><img src="https://images.theconversation.com/files/312729/original/file-20200130-41532-ve90i6.jpg?ixlib=rb-1.1.0&rect=8%2C0%2C799%2C622&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The now defunct Infrared Astronomical Telescope was one of the satellites involved in the near-collision.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:IRAS_in_orbit.jpg">NASA/JPL</a></span></figcaption></figure><p>It appears we have missed another close call between two satellites – but how close did we really come to a catastrophic event in space?</p>
<p>It all began with a <a href="https://twitter.com/LeoLabs_Space/status/1221908248305061889">series of tweets from LeoLabs</a>, a company that uses radar to track satellites and debris in space. It predicted that two obsolete satellites orbiting Earth had a 1 in 100 chance of an almost direct head-on collision at 9:39am AEST on 30 January, with potentially devastating consequences. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1221908248305061889"}"></div></p>
<p>LeoLabs estimated that the satellites could pass within 15-30m of one another. Neither satellite could be controlled or moved. All we could do was watch whatever unfolded above us.</p>
<p>Collisions in space can be disastrous and can send high-speed debris in all directions. This endangers other satellites, future launches, and especially crewed space missions. </p>
<p>As a point of reference, NASA often moves the International Space Station when the risk of collision is just 1 in 100,000. Last year the European Space Agency moved one of its satellites when the likelihood of collision with a SpaceX satellite was estimated at 1 in 50,000. However, this increased to 1 in 1,000 when the US Air Force, which maintains perhaps the most comprehensive catalogue of satellites, provided more detailed information.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/you-me-and-debris-australia-should-help-clear-space-junk-9919">You, me and debris: Australia should help clear 'space junk'</a>
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</em>
</p>
<hr>
<p>Following LeoLabs’ warning, other organisations such as the Aerospace Corporation began to provide similarly worrying predictions. In contrast, calculations based on publicly available data were far more optimistic. Neither the US Air Force nor NASA issued any warning. </p>
<p>This was notable, as the United States had a role in the launch of both satellites involved in the near-miss. The first is the <a href="https://www.jpl.nasa.gov/missions/infrared-astronomical-satellite-iras/">Infrared Astronomical Satellite (IRAS)</a>, a large space telescope weighing around a tonne and launched in 1983. It successfully completed its mission later that year and has floated dormant ever since. </p>
<p>The second satellite has a slightly more intriguing story. Known as <a href="https://www.n2yo.com/satellite/?s=2828">GGSE-4</a>, it is a formerly secret government satellite launched in 1967. It was part of a much larger project to capture radar emissions from the Soviet Union. This particular satellite also contained an experiment to explore ways to stabilise satellites using gravity. </p>
<p>Weighing in at 83kg, it is much smaller than IRAS, but it has a very unusual and unfortunate shape. It has an 18m protruding arm with a weight on the end, thus making it a much larger target. </p>
<p>Almost 24 hours later, <a href="https://twitter.com/LeoLabs_Space/status/1222304111527374853">LeoLabs tweeted again</a>. It downgraded the chance of a collision to 1 in 1,000, and revised the predicted passing distance between the satellites to 13-87m. Although still closer than usual, this was a decidedly smaller risk. But less than 15 hours after that, the company <a href="https://twitter.com/LeoLabs_Space/status/1222547865567887361">tweeted yet again</a>, raising the probability of collision back to 1 in 100, and then to a very alarming 1 in 20 after learning about the shape of GGSE-4. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1222547865567887361"}"></div></p>
<p>The good news is that the two satellites appear to have missed one another. Although there were a handful of eyewitness accounts of the IRAS satellite appearing to pass unharmed through the predicted point of impact, it can still take a few hours for scientists to confirm that a collision did not take place. LeoLabs has <a href="https://twitter.com/LeoLabs_Space/status/1222702184711757825">since confirmed</a> it has not detected any new space debris. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1222702184711757825"}"></div></p>
<p>But why did the predictions change so dramatically and so often? What happened?</p>
<h2>Tricky situation</h2>
<p>The real problem is that we don’t really know precisely where these satellites are. That requires us to be extremely conservative, especially given the cost and importance of most active satellites, and the dramatic consequences of high-speed collisions.</p>
<p>The tracking of objects in space is often called <a href="https://www.unsw.adfa.edu.au/space-research/research-themes/space-situational-awareness">Space Situational Awareness</a>, and it is a very difficult task. One of the best methods is radar, which is expensive to build and operate. Visual observation with telescopes is much cheaper but comes with other complications, such as weather and lots of moving parts that can break down. </p>
<p>Another difficulty is that our models for predicting satellites’ orbits don’t work well in lower orbits, where drag from Earth’s atmosphere can become a factor.</p>
<p>There is yet another problem. Whereas it is in the best interest of commercial satellites for everyone to know exactly where they are, this is not the case for military and spy satellites. Defence organisations do not share the full list of objects they are tracking. </p>
<p>This potential collision involved an ancient spy satellite from 1967. It is at least one that we can see. Given the difficulty of just tracking the satellites that we know about, how will we avoid satellites that are trying their hardest not to be seen?</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/trash-or-treasure-a-lot-of-space-debris-is-junk-but-some-is-precious-heritage-82832">Trash or treasure? A lot of space debris is junk, but some is precious heritage</a>
</strong>
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</p>
<hr>
<p>In fact, much research has gone into building stealth satellites that are invisible from Earth. Even commercial industry is considering making satellites that are harder to see, partly in response to astronomers’ own concerns about objects blotting out their view of the heavens. SpaceX is considering building “dark satellites” the reflect less light into telescopes on Earth, which will only make them harder to track.</p>
<h2>What should we do?</h2>
<p>The solution starts with developing better ways to track satellites and space debris. Removing the junk is an important next step, but we can only do that if we know exactly where it is. </p>
<p>Western Sydney University is developing <a href="https://www.westernsydney.edu.au/icns/astrosite">biology-inspired cameras</a> that can see satellites during the day, allowing them to work when other telescopes cannot. These sensors can also see satellites when they move in front of bright objects like the Moon.</p>
<p>There is also no clear international space law or policy, but a strong need for one. Unfortunately, such laws will be impossible to enforce if we cannot do a better job of figuring out what is happening in orbit around our planet.</p><img src="https://counter.theconversation.com/content/130794/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gregory Cohen receives funding for space applications of neuormorphic imaging from the Royal Australian Air Force (RAAF), the United States Air Force Office of Scientific Research (AFOSR), and the Defense Innovation Hub (DIH).</span></em></p>Two defunct satellites passed within metres of one another, prompting renewed focus on the dangers of space debris. But with many satellites treated as military secrets, how do we track the hazards?Gregory Cohen, Associate Professor, Western Sydney UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1289982019-12-18T18:58:08Z2019-12-18T18:58:08Z‘The size, the grandeur, the peacefulness of being in the dark’: what it’s like to study space at Siding Spring Observatory<figure><img src="https://images.theconversation.com/files/307307/original/file-20191217-123992-12tnqvo.jpg?ixlib=rb-1.1.0&rect=8%2C17%2C5739%2C3025&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Today we hear about some of the fascinating space research underway at Siding Spring Observatory – and how, despite gruelling hours and endless paperwork, astronomers retain their sense of wonder for the night sky.</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>How did our galaxy form? How do galaxies evolve over time? Where did the Sun’s lost siblings end up?</p>
<p>Three hours north-east of Parkes lies a remote astronomical research facility, unpolluted by city lights, where researchers are collecting vast amounts of data in an effort to unlock some of the biggest questions about our Universe. </p>
<p>Siding Spring Observatory, or SSO, is one of Australia’s top sites for astronomical research. You’ve probably heard of the Parkes telescope, made famous by the movie The Dish, but SSO is also a key character in Australia’s space research story.</p>
<p>In this episode, astrophysics student and Conversation intern Cameron Furlong goes to SSO to check out the huge Anglo Australian Telescope (AAT), the largest optical telescope in Australia.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/307308/original/file-20191217-124022-j2z8ws.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/307308/original/file-20191217-124022-j2z8ws.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/307308/original/file-20191217-124022-j2z8ws.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/307308/original/file-20191217-124022-j2z8ws.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/307308/original/file-20191217-124022-j2z8ws.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/307308/original/file-20191217-124022-j2z8ws.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/307308/original/file-20191217-124022-j2z8ws.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/307308/original/file-20191217-124022-j2z8ws.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Siding Spring Observatory, north east of Parkes.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/darkness-is-disappearing-and-thats-bad-news-for-astronomy-51989">Darkness is disappearing and that's bad news for astronomy</a>
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</em>
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<p>And we hear about Huntsman, a new specialised telescope that uses off-the-shelf Canon camera lenses – a bit like those you see sports photographers using at the cricket or the footy – to study very faint regions of space around other galaxies.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/307298/original/file-20191216-124016-b2k0ag.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/307298/original/file-20191216-124016-b2k0ag.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/307298/original/file-20191216-124016-b2k0ag.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/307298/original/file-20191216-124016-b2k0ag.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/307298/original/file-20191216-124016-b2k0ag.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/307298/original/file-20191216-124016-b2k0ag.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/307298/original/file-20191216-124016-b2k0ag.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/307298/original/file-20191216-124016-b2k0ag.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>
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<span class="caption">Students use telescopes to observe the night sky near Coonabarabran, not far from SSO.</span>
<span class="attribution"><span class="source">Cameron Furlong</span></span>
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<p>Listen in to hear more about some of the most fascinating space research underway in Australia – and how, despite gruelling hours and endless paperwork, astronomers retain their sense of wonder for the night sky. </p>
<p>“For me, it means remembering how small I am in this enormous Universe. I think it’s very easy to forget, when you go about your daily life,” said Richard McDermid, an ARC Future Fellow and astronomer at Macquarie University.</p>
<p>“It’s nice to get back into it to a dark place and having a clear sky. And then you get to remember all the interesting and fascinating things, the size, the grandeur and the peacefulness of being in the dark.”</p>
<h2>New to podcasts?</h2>
<p>Podcasts are often best enjoyed using a podcast app. All iPhones come with the Apple Podcasts app already installed, or you may want to listen and subscribe on another app such as Pocket Casts (click <a href="https://pca.st/VTv7">here</a> to listen to Trust Me, I’m An Expert on Pocket Casts).</p>
<p>You can also hear us on Stitcher, Spotify or any of the apps below. Just pick a service from one of those listed below and click on the icon to find Trust Me, I’m An Expert.</p>
<p><a href="https://itunes.apple.com/au/podcast/trust-me-im-an-expert/id1290047736?mt=2&ign-mpt=uo%3D8"><img src="https://images.theconversation.com/files/233721/original/file-20180827-75984-1gfuvlr.png" alt="Listen on Apple Podcasts" width="268" height="68"></a> <a href="https://www.google.com/podcasts?feed=aHR0cHM6Ly90aGVjb252ZXJzYXRpb24uY29tL2F1L3BvZGNhc3RzL3RydXN0LW1lLXBvZGNhc3QucnNz"><img src="https://images.theconversation.com/files/233720/original/file-20180827-75978-3mdxcf.png" alt="" width="268" height="68"></a></p>
<p><a href="https://www.stitcher.com/podcast/the-conversation/trust-me-im-an-expert"><img src="https://images.theconversation.com/files/233716/original/file-20180827-75981-pdp50i.png" alt="Stitcher" width="300" height="88"></a> <a href="https://tunein.com/podcasts/News--Politics-Podcasts/Trust-Me-Im-An-Expert-p1035757/"><img src="https://images.theconversation.com/files/233723/original/file-20180827-75984-f0y2gb.png" alt="Listen on TuneIn" width="318" height="125"></a></p>
<p><a href="https://radiopublic.com/trust-me-im-an-expert-Wa3E5A"><img class="alignnone size-medium wp-image-152" src="https://images.theconversation.com/files/233717/original/file-20180827-75990-86y5tg.png?ixlib=rb-1.1.0&q=45&auto=format&w=268&fit=clip" alt="Listen on RadioPublic" width="268" height="87"></a> <a href="https://open.spotify.com/show/7myc7drbLJVaRitAMXLB7V"><img src="https://images.theconversation.com/files/237984/original/file-20180925-149976-1ks72uy.png?ixlib=rb-1.1.0&q=45&auto=format&w=268&fit=clip" width="268" height="82"></a> </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/trust-me-im-an-expert-what-science-says-about-how-to-lose-weight-and-whether-you-really-need-to-122635">Trust Me, I'm An Expert: what science says about how to lose weight and whether you really need to</a>
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</em>
</p>
<hr>
<p><strong>Additional audio</strong></p>
<p><em>Kindergarten by Unkle Ho, from <a href="https://www.elefanttraks.com/">Elefant Traks.</a></em></p>
<p><em><a href="https://freemusicarchive.org/music/Podington_Bear/Textural/Lucky_Stars_1189">Lucky Stars</a> by Podington Bear from Free Music Archive.</em></p>
<p><em><a href="https://freemusicarchive.org/music/Blue_Dot_Sessions/20190309173200900/Slimheart">Slimheart by Blue Dot Sessions</a> from Free Music Archive.</em></p>
<p><em><a href="https://freemusicarchive.org/music/Kai_Engel">Illumination</a> by Kai Engel from Free Music Archive.</em></p>
<p><em><a href="https://freemusicarchive.org/music/Xylo-Ziko/Phase_2">Phase 2 by Xylo-Ziko</a> from Free Music Archive.</em></p>
<p><em><a href="https://freemusicarchive.org/music/Kri_Tik">Extra Dimensions by Kri Tik</a> from Free Music Archive.</em></p>
<p><em><a href="https://freemusicarchive.org/music/Meydan">Pure Water by Meydän</a>, from Free Music Archive.</em></p>
<h2>Images</h2>
<p><em>Shutterstock</em></p>
<p><em>Cameron Furlong</em></p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/antibiotic-resistant-superbugs-kill-32-plane-loads-of-people-a-week-we-can-all-help-fight-back-125813">Antibiotic resistant superbugs kill 32 plane-loads of people a week. We can all help fight back</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/128998/count.gif" alt="The Conversation" width="1" height="1" />
Three hours north-east of Parkes lies a remote astronomical research facility, unpolluted by city lights, where researchers are trying to unlock some of the biggest questions about our Universe.Sunanda Creagh, Senior EditorCameron Furlong, Editorial InternLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1151672019-04-10T16:05:17Z2019-04-10T16:05:17ZFirst black hole photo confirms Einstein’s theory of relativity<figure><img src="https://images.theconversation.com/files/268630/original/file-20190410-2905-t29uaz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Finally dragged out of the shadows.</span> <span class="attribution"><a class="source" href="https://eventhorizontelescope.org">Event Horizon Telescope Collaboration / </a></span></figcaption></figure><p>Black holes are long-time superstars of science fiction. But their Hollywood fame is a little strange given that no-one has ever actually seen one – at least, until now. If you needed to see to believe, then thank the <a href="https://eventhorizontelescope.org">Event Horizon Telescope</a> (EHT), which has just produced the first ever direct image of a black hole. This amazing feat required global collaboration to turn the Earth into one giant telescope and image an object thousands of trillions of kilometres away.</p>
<p>As stunning and ground-breaking as it is, the EHT project is not just about taking on a challenge. It’s an unprecedented test of whether Einstein’s <a href="https://theconversation.com/explainer-einsteins-theory-of-general-relativity-3481">ideas</a> about the very nature of space and time hold up in extreme circumstances, and looks closer than ever before at the role of black holes in the universe. </p>
<p>To cut a long story short: Einstein was right.</p>
<h2>Capturing the uncapturable</h2>
<p>A black hole is a region of space whose mass is so large and dense that not even light can escape its gravitational attraction. Against the black backdrop of the inky beyond, capturing one is a near impossible task. But thanks to Stephen Hawking’s groundbreaking work, we know that the colossal masses <a href="https://theconversation.com/black-holes-arent-totally-black-and-other-insights-from-stephen-hawkings-groundbreaking-work-93458">are not just black abysses</a>. Not only are they able to emit huge jets of plasma, but their immense gravity pulls in streams of matter into its core.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1116287990928687105"}"></div></p>
<p>When matter approaches a black hole’s event horizon – the point at which not even light can escape – it forms an orbiting disk. Matter in this disk will convert some of its energy to friction as it rubs against other particles of matter. This warms up the disk, just as we warm our hands on a cold day by rubbing them together. The closer the matter, the greater the friction. Matter closer to the event horizon glows brilliantly bright with the heat of hundreds of Suns. It is this light that the EHT detected, along with the “silhouette” of the black hole. </p>
<p>Producing the image and analysing such data is an amazingly hard task. As an astronomer who studies <a href="https://ui.adsabs.harvard.edu/abs/2018MNRAS.475.4223G/abstract">black holes in far away galaxies</a>, I cannot usually even image a single star in those galaxies clearly, let alone see the black hole at their centres.</p>
<p>The EHT team decided to target two of the closest supermassive black holes to us – both in the large elliptical shaped galaxy, M87, and in Sagittarius A*, at the centre of our Milky Way. </p>
<p>To give a sense of how hard this task is, while the Milky Way’s black hole has a mass of 4.1 million Suns and a diameter of 60 million kilometres, it is 250,614,750,218,665,392 kilometres away from Earth – thats the equivalent of travelling from London to New York 45 trillion times. As <a href="https://www.youtube.com/watch?v=hMsNd1W_lmE">noted by the EHT team</a>, it is like being in New York and trying to count the dimples on a golf ball in Los Angeles, or imaging an orange on the moon. </p>
<p>To photograph something so impossibly far away, the team needed a telescope as big as the Earth itself. In the absence of such a gargantuan machine, the EHT team connected together telescopes from around the planet, and combined their data. To capture an accurate image at such a distance, the telescopes needed to be stable, and their readings completely synchronised.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/hMsNd1W_lmE?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">How the researchers captured the first image of a black hole.</span></figcaption>
</figure>
<p>To accomplish this challenging feat, the team used atomic clocks so accurate that they lose just one second per hundred million years. The 5,000 terabytes of data collected was so large that it had to be stored on hundreds of hard drives and physically delivered to a supercomputer, which corrected the time differences in the data and produced the image above.</p>
<h2>General Relativity vindicated</h2>
<p>With a sense of excitement, I watched the live stream showing the image of the black hole from the centre of M87 for the first time.</p>
<p>The most important initial take-home is that Einstein was right. <a href="https://theconversation.com/gravitational-waves-discovered-top-scientists-respond-53956">Again</a>. His general theory of relativity has passed two serious tests from the universe’s most extreme conditions in the last few years. Here, Einstein’s theory predicted the observations from M87 with unerring accuracy, and is seemingly the correct description of the nature of space, time, and gravity.</p>
<p>The measurements of the speeds of matter around the centre of the black hole are consistent with being near the speed of light. From the image, the EHT scientists determined that the M87 black hole is 6.5 billion times the mass of the Sun and 40 billion km across – that’s larger than Neptune’s 200-year orbit of the sun. </p>
<p>The Milky Way’s black hole was too challenging to image accurately this time round due to rapid variability in light output. Hopefully, more telescopes will be added to the EHT’s array soon, to get ever clearer images of these fascinating objects. I have no doubt that in the near future we will be able to gaze upon the dark heart of our very own galaxy.</p>
<p><em>This piece has been updated to include a picture of Katie Bouman, a computer scientist who developed the algorithm that made the black hole photo possible.</em></p><img src="https://counter.theconversation.com/content/115167/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kevin Pimbblet receives funding from STFC. </span></em></p>Scientists turned Earth into one giant telescope to capture the uncapturable.Kevin Pimbblet, Senior Lecturer in Physics, University of HullLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/970442018-08-21T10:32:47Z2018-08-21T10:32:47ZSwift’s telescope reveals birth, deaths and collisions of stars through 1 million snapshots in UV<figure><img src="https://images.theconversation.com/files/221208/original/file-20180531-69481-kmpc6s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Technicians prepare Swift's UVOT for vibration testing on Aug. 1, 2002, more than two years before launch, in the High Bay Clean Room at NASA's Goddard Space Flight Center in Greenbelt, Md.
</span> <span class="attribution"><a class="source" href="https://www.nasa.gov/mission_pages/swift/bursts/swift-images.html">NASA's Goddard Space Flight Center </a></span></figcaption></figure><p>Imagine if the color camera had never been invented and all our images were in black and white. The world would still look beautiful, but incomplete. For thousands of years, that was how humans saw the universe. On Earth, we can only see part of the light that stars emit.</p>
<p>Much of what we can’t see – in the infrared, the ultraviolet, the X-ray and the gamma ray wavelengths – is blocked by the Earth’s atmosphere. For the most part, this is a good thing. The atmosphere traps infrared light keeping the Earth warm at night and blocks high-energy ultraviolet light, X-rays and gamma rays, keeping us safe from deadly cosmic radiation, while letting in visible portions of the spectrum of light. For astronomers, however, this has a drawback: We look at the universe with one eye shut, unable to receive all of the information the universe is sending to us.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/221252/original/file-20180531-69514-1avj865.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/221252/original/file-20180531-69514-1avj865.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=225&fit=crop&dpr=1 600w, https://images.theconversation.com/files/221252/original/file-20180531-69514-1avj865.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=225&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/221252/original/file-20180531-69514-1avj865.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=225&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/221252/original/file-20180531-69514-1avj865.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=282&fit=crop&dpr=1 754w, https://images.theconversation.com/files/221252/original/file-20180531-69514-1avj865.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=282&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/221252/original/file-20180531-69514-1avj865.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=282&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Visible light is just a tiny part of the electromagnetic spectrum.</span>
<span class="attribution"><a class="source" href="https://imagine.gsfc.nasa.gov/Images/science/EM_spectrum_compare_level1_lg.jpg">NASA</a></span>
</figcaption>
</figure>
<p>Launched on November 20, 2004, and orbiting an altitude of 340 miles, NASA’s <a href="https://swift.gsfc.nasa.gov">Neil Gehrels Swift Observatory</a> has three telescopes that monitor the universe using wavelengths of light that are blocked by Earth’s atmosphere. These included the X-Ray Telescope, the gamma-ray-sensitive Burst-Alert Telescope and the Ultraviolet Optical Telescope (UVOT). The UVOT recently delivered its 1 millionth image – data that astrophysicists like me use to gain insights into everything from the origins of the universe to the chemical composition of nearby comets.</p>
<h2>Watching the birth of black holes</h2>
<p>Swift’s primary mission is to study the afterglow of gamma ray bursts (GRBs) – which document the birth of black holes. Black holes are forged in the most violent explosions in the universe – the explosion of a massive star or the merging of two neutron stars (the shriveled husks left over from past stellar explosions). These explosions are so powerful – producing tens to hundreds of billions of times more energy than the sun – that even though they occur billions of light years away from Earth, they can still be detected by instruments like Swift. In fact, the first GRBs were detected by the <a href="https://heasarc.gsfc.nasa.gov/docs/heasarc/missions/vela5a.html">Vela satellites</a>, which were built to detect the explosions of nuclear weapons. </p>
<p>Over nearly 14 years, Swift has studied over a thousand GRBs. In doing so, it has revealed what powers them and given us glimpses into the furthest reaches of the cosmos, to the time when the first stars were being formed after the Big Bang.</p>
<p>However, one of the things you learn working on a space telescope mission is that if you build it, they will come. The mission provides capabilities to the community of astrophysicists – simultaneous X-ray/UV imaging and a rapid response to requests to observe and photograph specific sections of the sky – which are only available to Swift. We can focus our telescopes on an object of interest within hours of a “Target of Opportunity” request through our website, something no other mission can do. UVOT also fills an important niche by observing larger areas of the sky than can be observed with the more powerful UV instruments aboard the <a href="https://www.nasa.gov/mission_pages/hubble/main/index.html">Hubble Space Telescope</a>. These capabilities have proved a boon to the community and enabled study all sorts of objects and phenomenon beyond GRBs. </p>
<h2>Swift’s ultraviolet-aided discoveries</h2>
<p>Nearby galaxies are full of activity with new stars being formed. Swift is able to capture panoramic ultraviolet images that highlight the youngest, most massive stars in these galaxies. This gives us insight into what the universe has been doing over the last few hundred million years. My research team’s work has focused on nearby galaxies – like Andromeda and the Magellanic Clouds – to reveal what processes drive their past and ongoing star formation.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/221218/original/file-20180531-69514-1ojaoax.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/221218/original/file-20180531-69514-1ojaoax.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=298&fit=crop&dpr=1 600w, https://images.theconversation.com/files/221218/original/file-20180531-69514-1ojaoax.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=298&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/221218/original/file-20180531-69514-1ojaoax.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=298&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/221218/original/file-20180531-69514-1ojaoax.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=374&fit=crop&dpr=1 754w, https://images.theconversation.com/files/221218/original/file-20180531-69514-1ojaoax.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=374&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/221218/original/file-20180531-69514-1ojaoax.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=374&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">On the left is an image of the nearby galaxy NGC 3623 taken with UV. On the right is an optical image. Note how the galaxies spiral arms — where new stars are being born — stand out in the ultraviolet wavelengths emitted by these hot objects.</span>
<span class="attribution"><span class="source">NASA/Swift/L.McCauley, PSU</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>With UVOT, we get a much better view of supernova explosions. These can occur when a white dwarf, the remnant of a star like the sun, explodes, or during the final death throes of a massive star, more than eight times the mass of the sun. These events generate enormous amounts of ultraviolet light, and Swift has a unique ability to observe them within hours of discovery. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/221213/original/file-20180531-69501-1hs7vbv.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/221213/original/file-20180531-69501-1hs7vbv.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=384&fit=crop&dpr=1 600w, https://images.theconversation.com/files/221213/original/file-20180531-69501-1hs7vbv.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=384&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/221213/original/file-20180531-69501-1hs7vbv.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=384&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/221213/original/file-20180531-69501-1hs7vbv.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=482&fit=crop&dpr=1 754w, https://images.theconversation.com/files/221213/original/file-20180531-69501-1hs7vbv.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=482&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/221213/original/file-20180531-69501-1hs7vbv.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=482&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">On the left is an ultraviolet composite made from several images of the Whirpool Galaxy (M51) taken between 2005-2007. The image on the right was made in June 2011, shortly after astronomers detected the explosion of a massive star in one of the galaxy’s outer spiral arms. The object is marked by the red circle.</span>
<span class="attribution"><span class="source">NASA/Swift/E. Hoversten, PSU</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Comets sweep through our solar system, transforming from a frozen solid ball to a vapor as they approach the sun and creating magnificent tails of ionized particles. Swift studies these comets, and analyzes their chemical composition by breaking the light they emit into different wavelengths. Swift also allows scientists to measure a comet’s rotation by seeing how the light changes over time. This has revealed that violent eruptions on the comet surface can dramatically alter a comet’s path. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/221217/original/file-20180531-69484-12raesi.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/221217/original/file-20180531-69484-12raesi.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=541&fit=crop&dpr=1 600w, https://images.theconversation.com/files/221217/original/file-20180531-69484-12raesi.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=541&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/221217/original/file-20180531-69484-12raesi.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=541&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/221217/original/file-20180531-69484-12raesi.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=680&fit=crop&dpr=1 754w, https://images.theconversation.com/files/221217/original/file-20180531-69484-12raesi.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=680&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/221217/original/file-20180531-69484-12raesi.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=680&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">This image of Comet Lulin was taken by Swift on January 28, 2009. It shows data obtained by Swift’s Ultraviolet/Optical Telescope (blue and green) and X-Ray Telescope (red). The image of the star field (white) was acquired by the Digital Sky Survey. At the time of the observation, comet Lulin was 99.5 million miles from Earth and 115.3 million miles from the sun. The ultraviolet light comes from hydroxyl molecules and shows that, at this time, Lulin was shedding 800 gallons of water every second.</span>
<span class="attribution"><span class="source">D. Bodewits/Swift/NASA</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>One of the most exciting discoveries that Swift made was connected with the recent discovery of gravitational waves by the <a href="https://losc.ligo.org/detector_status/">Laser Interferometer Gravitational-Wave Observatory</a> (LIGO). Gravitational waves are distortions in the fabric of spacetime created by the motions of extremely massive objects. In August of 2017, two neutrons stars collided in a distant galaxy, creating gravitational waves powerful enough to be detected on Earth. Swift was one of an army of telescopes that looked for the source of the gravitational waves. The mad scramble over those few days led to one of the most exciting discoveries of the last decade – a luminous afterglow from the source of the gravitational waves. This has opened up new branches of science by connecting a new way of studying the universe – through gravitational waves – to the traditional way – through light.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/221384/original/file-20180601-142102-2rarg4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/221384/original/file-20180601-142102-2rarg4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=532&fit=crop&dpr=1 600w, https://images.theconversation.com/files/221384/original/file-20180601-142102-2rarg4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=532&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/221384/original/file-20180601-142102-2rarg4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=532&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/221384/original/file-20180601-142102-2rarg4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=669&fit=crop&dpr=1 754w, https://images.theconversation.com/files/221384/original/file-20180601-142102-2rarg4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=669&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/221384/original/file-20180601-142102-2rarg4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=669&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">An artist’s depiction of a space warping collision of two merging neutron stars. The ripples represent the gravitational waves that distort the space-time grid. The narrow beams shooting out of the collision show the gamma rays burst that are released after the gravitational waves. The yellow clouds glow with other wavelengths of light that are generated in the collision.</span>
<span class="attribution"><a class="source" href="https://www.ligo.caltech.edu/page/press-release-gw170817">NSF/LIGO/Sonoma State University/A. Simonnet</a></span>
</figcaption>
</figure>
<p>UVOT has been taking snapshots of the universe since 2004 and finally piled up its millionth image. Its success is a testament to the international team of engineers, scientists and staff at the three institutions that support it – the <a href="http://www.psu.edu">Pennsylvania State University</a>; <a href="http://www.ucl.ac.uk/mssl/">Mullard Space Science Laboratory</a> in Surrey, England; and NASA’s <a href="https://www.nasa.gov/goddard">Goddard Space Flight Center</a> in Greenbelt, Maryland. It has been my privilege to be a part of this team for the last nine years. What does the future hold for UVOT? We hope to find more sources of gravitational waves, survey nearby galaxies, study even more supernovae, and monitor how objects in the universe change over time.</p>
<p>Here’s to the next million images.</p><img src="https://counter.theconversation.com/content/97044/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Siegel is a Research Professor at Pennsylvania State University and receives research funding from NASA.</span></em></p>The Swift Observatory passed a milestone: 1 million snapshots of the universe. These exquisite and revealing pictures have captured the births and deaths of stars, gravitational waves and comets.Michael Siegel, Research Professor of Astronomy and Astrophysics, Penn StateLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1003972018-07-30T12:06:19Z2018-07-30T12:06:19ZHow my astronomy data from the Lovell telescope was used to create an immersive light and sound show<figure><img src="https://images.theconversation.com/files/229413/original/file-20180726-106527-1akfz75.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Translating the signals.</span> <span class="attribution"><span class="source">Chirs Foster</span>, <span class="license">Author provided</span></span></figcaption></figure><p>As a scientist, I was recently involved in bringing my work to the big screen. This was not a Hollywood sci-fi blockbuster but “big screen” in the literal sense: an art production about science that used the Lovell radio telescope, a 3,200-ton steel behemoth supporting of a 76-metre wide dish, to generate and show audio-visual art that drew on scientific data.</p>
<p>I have been involved with numerous public engagement opportunities over the years: giving public lectures, visiting students in schools, interacting on social media, being interviewed about new discoveries. There is however another form of public engagement that I have come to experience in the past year, which I would probably never have considered if not for the fact that it came knocking at my door: connecting with an artist developing a piece inspired by the scientific work that my colleagues and I do.</p>
<p>This is quite a contrast for astronomers working at the Jodrell Bank Observatory, given that a lot of our focus is normally devoted to activities such as connecting our telescope to various networks of radio dishes in order to produce <a href="http://www.jive.eu/new-images-super-telescope-bring-astronomers-step-closer-understanding-dark-matter">ultra-sharp images of the sky</a> or monitoring the clockwork rotation of <a href="http://www.jb.man.ac.uk/pulsar/Education/Sounds/">rapidly spinning, ultra-dense exploded stellar leftovers</a> known as pulsars. In a way though, it is perhaps not unexpected that sooner or later someone would draw inspiration from the rich history of astronomical breakthroughs accomplished using the telescope.</p>
<p>It pretty much started with an email – the modern door knock – from fellow astronomer Tim O'Brien, asking if my colleagues and I would discuss our research with an artist who had been commissioned to create an art experience that would be projected onto the Lovell radio telescope as part of the <a href="https://www.discoverthebluedot.com">bluedot festival</a>. My immediate answer was yes; who would turn down the opportunity to see their work projected on a structure the area of 20 standard IMAX screens?</p>
<h2>Art meets science</h2>
<p>The original feeling that drove me to get involved is the same that pushes me to get up every morning to study our universe: curiosity. The unsettling difference is that with the art project it feels like I am the one under scrutiny. I am not the subject – my data is – but there is this a strange relationship that I develop with data over time. A kind of intimacy.</p>
<p>After all, I may spend anywhere between a couple of months to, in some cases, multiple years, working on the same set of data: processing, analysis, modelling them, and then redoing it all over. So if someone is interested in my research in order to produce art, I have an immense trepidation to discover what the artist will do with my data.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/eZYXitX17G8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Hidden in Plain Sight by Addie Wagenknecht on the Lovell telescope, commissioned by Abandon Normal Devices.</span></figcaption>
</figure>
<p>Astrophysics, like many other branches of science, lies at the cutting edge of what is called big data. We collect huge amount of data and the relevant information manifests itself as a very subtle signal buried in it. In my case my science focuses on pulsars, which illuminate the sky like (extremely faint) cosmic lighthouses. In that sense, Hidden in Plain Sight, by artist <a href="https://en.wikipedia.org/wiki/Addie_Wagenknecht">Addie Wagenknecht</a>, is the perfect epitome of our day-to-day research challenges.</p>
<p>The artwork sits at the crossroad with science as Wagenknecht uses machine learning – using artificial intelligence to try and classify and interpret data on its own – in order to turn our data into art. The visual style could be described as a mosaic of irregular polygons that resembles modern <a href="https://en.wikipedia.org/wiki/Dazzle_camouflage">dazzle camouflage</a>. While it initially gave an impression of randomness, it gradually evolved into a more ordered rhythm of patterns varying in sized, shape and intensity.</p>
<p>Additionally we collaborated with Simon Jackson, an acoustic designer at engineering firm Arup to produce an immersive three-dimensional soundscape. The composition was informed and generated from data sets we shared. It rendered feelings of distance/proximity through direction of sound travel and variations in brightness/colours with frequency modulations.</p>
<p>Together, the sound and images translated the complexity and anomalies that signals gather on the journey to us.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/229006/original/file-20180724-194143-1wuvhbm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/229006/original/file-20180724-194143-1wuvhbm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/229006/original/file-20180724-194143-1wuvhbm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/229006/original/file-20180724-194143-1wuvhbm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/229006/original/file-20180724-194143-1wuvhbm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/229006/original/file-20180724-194143-1wuvhbm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/229006/original/file-20180724-194143-1wuvhbm.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">Artist Addie Wagenknecht at work with the data from the Lovell Telescope, Jodrell Bank Observatory at bluedot festival.</span>
<span class="attribution"><span class="source">Chris Foster</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Data as performance</h2>
<p>The fascinating discovery that I’ve made working with artists is that they don’t directly try to communicate my results like I would normally do in other engagement activities. Instead, the process is a more involved experience in which they attempt to extract the essence of the research in order to turn it into an audiovisual emotion. </p>
<p>In 2017 I collaborated with Tokyo-based artist Daito Manabe, <a href="http://www.jodrellbank.net/international-arts-science-residency-jodrell-bank/">who focused his attention</a> on sourcing live data from the Lovell telescope in order to turn the cosmic whispers it detected into sound and images. This was an interesting twist as the telescope acted both as projection medium and art material. The process involved in feeding data to the art installation closely followed the same steps employed to produce science, with the major difference arising in way the numbers are interpreted.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/229007/original/file-20180724-194131-14ccgz2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/229007/original/file-20180724-194131-14ccgz2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/229007/original/file-20180724-194131-14ccgz2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/229007/original/file-20180724-194131-14ccgz2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/229007/original/file-20180724-194131-14ccgz2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/229007/original/file-20180724-194131-14ccgz2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/229007/original/file-20180724-194131-14ccgz2.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">Imprint of lights passing in front of the telescope.</span>
<span class="attribution"><span class="source">Chris Foster</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The amazing aspect of being part of these projects is that the two artists I have worked with so far did not only soak up as much of science knowledge as they could, but they were also primarily interested in understanding the actual data that I work with at various stages of the research process. They ended up using the data directly as a way of performing their art.</p>
<p>The science vs art dialogue is a modest contribution on my part, but somehow, I cannot help and reflect on the <a href="http://www.jb.man.ac.uk/aboutus/lovell/build.html">interaction between</a> former Jodrell Bank director, Sir Bernard Lovell, and engineering prodigy Sir Charles Husband, which led to the master piece – both scientifically and artistically – now named after the former: the Lovell telescope.</p><img src="https://counter.theconversation.com/content/100397/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rene Breton is a Reader at the Jodrell Bank Centre for Astrophysics, The University of Manchester. He currently holds an ERC Starter Grant under the Horizon 2020 programme. The Hidden in Plain Sight project was a result of a collaboration involving several astronomers, with special thanks to Sally Cooper, Philippa Hartley, Mitch Mickaliger and Tim O'Brien.</span></em></p>Science and art meet on the ‘big screen’ – turning data into visuals at the Lovell Telescope, Jodrell Bank.Rene Breton, Reader in Astrophysics, University of ManchesterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/982742018-06-19T13:03:16Z2018-06-19T13:03:16ZAstronomers watch as black hole drags an exploding star to its death<figure><img src="https://images.theconversation.com/files/223028/original/file-20180613-32313-1an59er.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Artist conception of a tidal disruption event (TDE) that happens when a star passes fatally close to a supermassive black hole.</span> <span class="attribution"><span class="source">Sophia Dagnello, NRAO/AUI/NSF.</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Astronomers searching for <a href="https://theconversation.com/uk/topics/supernovae-4170">supernova</a> explosions accidentally stumbled upon a supermassive <a href="https://theconversation.com/uk/topics/black-holes-686">blackhole</a> recently as it devoured a wandering star that had fallen into its grasp. It is now hoped that this amazing discovery – captured for the first time – will help scientists understand the environment in which galaxies developed billions of years ago.</p>
<p>Some of the most luminous and energetic phenomena in the Universe are powered by the gradual build up of matter onto supermassive black holes in the centres of galaxies. When consuming matter, these black holes can shine brightly across the whole electromagnetic spectrum and in some cases produce jets of material which stream outward at close to the <a href="https://theconversation.com/uk/topics/speed-of-light-16770">speed of light</a>. </p>
<p>But supermassive black holes are not active all the time. So it would take more than a bit of luck to actually witness one of these monsters having a new meal. But that’s what happened when the international group of astronomers turned their collective gaze to a system of colliding galaxies called Arp299. </p>
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<p>The astronomers were hoping to catch a glimpse of a supernova (the cataclysmic explosion which happens when a massive star dies) but instead saw a supermassive black hole tearing a star apart. Their <a href="http://science.sciencemag.org/content/early/2018/06/13/science.aao4669">findings</a> directly imaged the results the dramatic event. This project, led by Seppo Mattila of the University of Turku in Finland and Miguel Perez-Torres of the Astrophysical Institute of Andalusia in Spain, involved a team of 36 scientists from 26 institutions – including researchers from the <a href="http://www.jodrellbank.manchester.ac.uk/">Jodrell Bank Centre for Astrophysics</a> – using telescopes from all around the world.</p>
<p>Now – for the first time – astronomers have pictures of the formation and expansion of the fast-moving jet of material which was ejected when the powerful gravity of a supermassive black hole tore apart the unlucky star. Only a small number of events of this kind – so called Tidal Disruption Events (TDEs) – have ever been detected.</p>
<p>Previously, <a href="https://doi.org/10.1016/j.jheap.2015.04.003">theorists had suggested</a> that material pulled from a doomed star such as this formed a rotating disk around the black hole, emitting intense X-rays and visible light. It was also thought that it would launch jets of material outward from the poles of the disk at nearly the speed of light. Theories which have proved to be correct.</p>
<p>The first indication of this material pulled from doomed star came in January 2005 when astronomers discovered a bright burst of infrared emissions coming from the nucleus of one of the colliding galaxies in Arp 299, nearly 150m light-years from Earth. Later that year radio observations revealed a new, distinct source of emission from the same location as the new bright infrared source, which they were able to follow as it evolved. </p>
<h2>Hiding in the dust</h2>
<p>For the next few years the team watched this new object using many of the most powerful telescopes in the world. While it remained bright at <a href="https://theconversation.com/uk/topics/infrared-2530">infrared</a> and radio wavelengths, no visible or X-ray light was detectable. The location of this source of infrared emissions was buried deep within the dust enshrouded heart of one of the colliding galaxies. It meant all of the X-ray and visible light expected to come from this source was absorbed by the dust before being re-emitted at longer wavelengths, in the infrared. </p>
<p>The researchers used the <a href="http://www.not.iac.es/">Nordic Optical Telescope</a> on the Canary Islands and <a href="http://www.spitzer.caltech.edu/">NASA’s Spitzer space telescope</a> to follow the object’s infrared emission.</p>
<p>Over the course of nearly ten years, the radio emissions were tracked using a technique called <a href="https://public.nrao.edu/telescopes/vlba/">Very Long Baseline Interferometry</a>. This involves remotely connecting many of the world’s most powerful radio telescopes – including the <a href="http://www.evlbi.org/">European VLBI Network</a> along with several <a href="http://www.e-merlin.ac.uk/">e-MERLIN telescopes</a> in the UK – in a series of simultaneous and coordinated observing campaigns.</p>
<p>This technique yields extremely high resolution imaging and provided the only method available to image the evolution of this new phenomena. The results showed that the source of radio emission was expanding in one direction – just as expected for a jet. The measured expansion indicated that the material in the jet moved at an average of a quarter the speed of light. </p>
<figure> <img src="https://media.giphy.com/media/vRJ2oXWwJXtlnVZJFD/giphy.gif"><figcaption>The first light at radio wavelengths of the TDE in Arp299 from 2005 to 2015. The movie plays side by side, showing images obtained with a world array of radio telescopes. Credit: Bill Saxton, NRAO/AUI/NSF.</figcaption></figure>
<h2>The tip of the iceberg</h2>
<p>Tidal Disruption Events like this are important episodes in the life of black holes and are thought to have been much more common in the distant universe. Disruption events, especially those witnessed in relatively local systems such as this, are important and unique opportunities to understand the consequences of such events, including how super-fast jets of material are formed and how they evolve. </p>
<p>Only a few of these types of events have previously been witnessed with most seen in visible light in optical surveys. This event is different because it’s location was shrouded by thick layers of dust meaning that no visible light could be seen at all. This location, of course, is where we may expect such events to occur – in the centres of galaxies containing a black hole and where large numbers of stars are forming. As such this discovery may be the tip of the iceberg of a hitherto hidden population of similar dramatic events.</p><img src="https://counter.theconversation.com/content/98274/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robert Beswick receives funding from the Science and Technology Reasearch Facility (STFC) and the European Union via Horizon 2020 </span></em></p>A team of astronomers captured the moment when a wayward star was pulled into the mouth of a supermassive black hole.Robert Beswick, Research scientist & Head of Science Operations and Support, e-MERLIN/VLBI National Radio Astronomy Facility, Jodrell Bank Centre for Astrophysics, University of ManchesterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/936882018-04-09T10:33:24Z2018-04-09T10:33:24ZGoodbye Kepler, hello TESS: Passing the baton in the search for distant planets<figure><img src="https://images.theconversation.com/files/213635/original/file-20180406-5578-h4ba8e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Imagined view from Kepler-10b, a planet that orbits one of the 150,000 stars that the Kepler spacecraft is monitoring.</span> <span class="attribution"><a class="source" href="https://www.nasa.gov/mission_pages/kepler/multimedia/images/kepler10_5.html">NASA/Kepler Mission/Dana Berry</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>For centuries, human beings have wondered about the possibility of other Earths orbiting distant stars. Perhaps some of these alien worlds would harbor strange forms of life or have unique and telling histories or futures. But it was only in 1995 that astronomers spotted the first planets orbiting sunlike stars outside of our solar system. </p>
<p>In the last decade, in particular, the number of planets known to orbit distant stars grew from under 100 to well over 2,000, with another 2,000 likely planets awaiting confirmation. Most of these new discoveries are due to a single endeavor — <a href="https://www.nasa.gov/mission_pages/kepler/overview/index.html">NASA’s Kepler mission</a>.</p>
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<figcaption>
<span class="caption">Number of confirmed exoplanets continues to grow.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/image-feature/ames/planetary-systems-by-number-of-known-planets">NASA/Ames Research Center/Wendy Stenzel and The University of Texas at Austin/Andrew Vanderburg</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/213633/original/file-20180406-5597-1xrglfy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/213633/original/file-20180406-5597-1xrglfy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/213633/original/file-20180406-5597-1xrglfy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=255&fit=crop&dpr=1 600w, https://images.theconversation.com/files/213633/original/file-20180406-5597-1xrglfy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=255&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/213633/original/file-20180406-5597-1xrglfy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=255&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/213633/original/file-20180406-5597-1xrglfy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=321&fit=crop&dpr=1 754w, https://images.theconversation.com/files/213633/original/file-20180406-5597-1xrglfy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=321&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/213633/original/file-20180406-5597-1xrglfy.jpg?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">Scientists can determine the size or radius of a planet by measuring the depth of the dip in brightness and knowing the size of the star.</span>
<span class="attribution"><span class="source">NASA Ames</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Kepler is a spacecraft housing a 1-meter telescope that illuminates a 95 megapixel digital camera the size of a cookie sheet. The instrument detected tiny variations in the brightness of 150,000 distant stars, looking for the telltale sign of a planet blocking a portion of the starlight as it transits across the telescope’s line of sight. It’s so sensitive that it could detect a fly buzzing around a single streetlight in Chicago from an orbit above the Earth. It can see stars shake and vibrate; it can see starspots and flares; and, in favorable situations, it can see planets as small as the moon.</p>
<p>Kepler’s thousands of discoveries revolutionized our understanding of planets and planetary systems. Now, however, the spacecraft has run out of its hydrazine fuel and officially entered retirement. Luckily for planet hunters, NASA’s TESS mission launched in April and will take over the exoplanet search.</p>
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<figcaption>
<span class="caption">Prepping the Kepler spacecraft pre-launch in 2009.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/mission_pages/kepler/multimedia/09-02-03.html">NASA/Tim Jacobs</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Kepler’s history</h2>
<p>The Kepler mission was conceived in the early 1980s by NASA scientist <a href="https://www.nasa.gov/mission_pages/kepler/team/william_borucki.html">Bill Borucki</a>, with later help from <a href="https://www.nasa.gov/mission_pages/kepler/team/David_Koch.html">David Koch</a>. At the time, there were no known planets outside of the solar system. Kepler was eventually assembled in the 2000s and launched in March of 2009. <a href="https://scholar.google.com/citations?user=pyXWfSgAAAAJ&hl=en&oi=ao">I joined</a> the Kepler Science Team in 2008 (as a wide-eyed rookie), eventually co-chairing the group studying the motions of the planets with <a href="https://www.nasa.gov/centers/ames/research/2007/lissauer.html">Jack Lissauer</a>.</p>
<p>Originally, the mission was planned to last for three and a half years with possible extensions for as long as the fuel, or the camera, or the spacecraft lasted. As time passed, portions of the camera began to fail but the mission has persisted. However, in 2013 <a href="https://www.nature.com/news/the-wheels-come-off-kepler-1.13032">when two of its four stabilizing gyros</a> (technically “reaction wheels”) stopped, the original Kepler mission effectively ended.</p>
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<figcaption>
<span class="caption">NASA scientists figured out how to use solar pressure to stabilize Kepler.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/kepler/keplers-second-light-how-k2-will-work">NASA Ames/W Stenzel</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Even then, with some ingenuity, NASA was able to use <a href="https://www.nasa.gov/kepler/keplers-second-light-how-k2-will-work">reflected light from the Sun to help steer the spacecraft</a>. The mission was rechristened as K2 and continued finding planets for another half decade. Now, with the fuel gauge near empty, the business of planet hunting is winding down and the spacecraft will be left adrift in the solar system. The final catalog of planet candidates from the original mission was completed late last year and the last observations of K2 are wrapping up.</p>
<h2>Kepler’s science</h2>
<p>Squeezing what knowledge we can from those data will continue for years to come, but what we’ve seen thus far has amazed scientists across the globe.</p>
<p>We have seen some planets that orbit their host stars in only a few hours and are so hot that the surface rock <a href="https://www.nasa.gov/content/disintegrating-super-mercury-size-planet">vaporizes and trails behind the planet</a> like a comet tail. Other systems have <a href="http://www.washington.edu/news/2012/06/21/astronomers-spy-two-planets-in-tight-quarters-as-they-orbit-a-distant-star/">planets so close together</a> that if you were to stand on the surface of one, the second planet would appear larger than 10 full moons. One system is so packed with planets that <a href="https://www.nasa.gov/image-feature/ames/kepler-90-planets-orbit-close-to-their-star">eight of them are closer to their star</a> than the Earth is to the Sun. <a href="https://www.nasa.gov/ames/kepler/nasa-keplers-hall-of-fame-small-habitable-zone-exoplanets">Many have planets</a>, and sometimes multiple planets, orbiting within the <a href="https://www.nasa.gov/ames/kepler/habitable-zones-of-different-stars">habitable zone</a> of their host star, where liquid water may exist on their surfaces.</p>
<p>As with any mission, the Kepler package came with trade-offs. It needed to stare at a single part of the sky, blinking every 30 minutes, for four straight years. In order to study enough stars to make its measurements, the stars had to be quite distant – just as when you stand in the middle of a forest, there are more trees farther from you than right next to you. Distant stars are dim, and their planets are hard to study. Indeed, one challenge for astronomers who want to study the properties of Kepler planets is that Kepler itself is often the best instrument to use. High quality data from ground-based telescopes requires long observations on the largest telescopes – precious resources that limit the number of planets that can be observed.</p>
<p>We now know that there are at least as many planets in the galaxy as there are stars, and many of those planets are quite unlike what we have here in the solar system. Learning the characteristics and personalities of the wide variety of planets requires that astronomers investigate the ones orbiting brighter and closer stars where more instruments and more telescopes can be brought to bear.</p>
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<figcaption>
<span class="caption">Once launched, TESS will identify exoplanets orbiting the brightest stars just outside our solar system.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/image-feature/goddard/2016/tess-artist-concept">NASA's Goddard Space Flight Center</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Enter TESS</h2>
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<figcaption>
<span class="caption">Duration of TESS’ observations on the celestial sphere, taking into account the overlap between sectors.</span>
<span class="attribution"><a class="source" href="https://tess.gsfc.nasa.gov/science.html">NASA</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p><a href="https://tess.gsfc.nasa.gov">NASA’s Transiting Exoplanet Survey Satellite mission</a>, led by MIT’s <a href="https://tess.gsfc.nasa.gov/dr-george-ricker-bio.html">George Ricker</a>, is searching for planets using the same detection technique that Kepler used. TESS’ orbit, rather than being around the Sun, has a close relationship with the Moon: TESS orbits the Earth twice for each lunar orbit. TESS’ observing pattern, rather than staring at a single part of the sky, will scan nearly the entire sky with overlapping fields of view (much like the petals on a flower).</p>
<p>Given what we learned from Kepler, astronomers expect TESS to find thousands more planetary systems. By surveying the whole sky, we will find systems that orbit stars 10 times closer and 100 times brighter than those found by Kepler – opening up new possibilities for measuring planet masses and densities, studying their atmospheres, characterizing their host stars, and establishing the full nature of the systems in which the planets reside. This information, in turn, will tell us more about our own planet’s history, how life may have started, what fates we avoided and what other paths we could have followed.</p>
<p>The quest to find our place in the universe continues as Kepler finishes its leg of the journey and TESS takes the baton.</p><img src="https://counter.theconversation.com/content/93688/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jason Steffen receives funding from NASA. </span></em></p>When NASA first started planning the Kepler mission, no one knew if the universe held any planets outside our solar system. Thousands of exoplanets later, the search enters a new phase as Kepler retires.Jason Steffen, Assistant Professor of Physics and Astronomy, University of Nevada, Las VegasLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/592522016-05-12T06:29:24Z2016-05-12T06:29:24ZKepler finds more ‘Earth-like planets’, but are they really like Earth?<figure><img src="https://images.theconversation.com/files/122237/original/image-20160512-18140-18pbsp8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">An artist's concept of select planetary discoveries made to date by NASA's Kepler space telescope.</span> <span class="attribution"><a class="source" href="https://www.nasa.gov/press-release/nasas-kepler-mission-announces-largest-collection-of-planets-ever-discovered">NASA/W. Stenzel</a></span></figcaption></figure><p>The number of confirmed planets orbiting other stars has just jumped by 1,284 with NASA’s <a href="https://www.nasa.gov/press-release/nasas-kepler-mission-announces-largest-collection-of-planets-ever-discovered">new analysis</a> of data from the <a href="http://kepler.nasa.gov/">Kepler</a> space telescope. </p>
<p>That takes the <a href="http://exoplanetarchive.ipac.caltech.edu/">total number of known exoplanets</a> to 3,264, with more than two-thirds (2,325) having been found by this one incredible space observatory alone.</p>
<p>But it is only a tiny subset of those new planets that have caught many people’s imagination. As NASA’s announcement says:</p>
<blockquote>
<p>[…] nearly 550 could be rocky planets like Earth, based on their size. Nine of these orbit in their sun’s habitable zone, which is the distance from a star where orbiting planets can have surface temperatures that allow liquid water to pool. With the addition of these nine, 21 exoplanets now are known to be members of this exclusive group.</p>
</blockquote>
<p>It’s a great hook – “NASA finds Earth-like planets around distant stars” – but is all the hype justified? And what does this mean for the future of our search for planets like the Earth, and for life elsewhere?</p>
<h2>Kepler: the first great exoplanet census</h2>
<p>The reason that Kepler has been so astonishingly successful at finding planets comes down to its design. It was built specifically to conduct the first great census of planets around other stars. </p>
<p>To do this, Kepler has played a numbers game. In the first phase of the mission, the spacecraft pointed at a single region of the night sky continuously for just over four years. </p>
<p>With a field of view of 115 square degrees, this allowed it to continuously monitor the brightness of more than 100,000 stars, looking for the telltale “winks” of a planetary transit in front of the star.</p>
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<p>Only a small fraction of all the planets out there will have orbits lined up in a way that allows them to transit their stars from our point of view. But given that we now know that most stars host planets (another of Kepler’s exciting revelations), a small fraction of 100,000 stars still gives many stars, and many planets to play with.</p>
<h2>Finding Earth-like planets</h2>
<p>Kepler’s data tells us two things about a given planet. The first is how long it takes to orbit its host, which in turn tells us how distant the planet is from that star.</p>
<p>The other thing we learn about the planet is its size relative to its host. This comes directly from the fraction of the star’s light that is blocked during a transit; a bigger planet blocks more light than a smaller one. </p>
<p>When we combine this with what we know of the star, it allows us to estimate the actual size of the planet. This is where our Earth-sized planets come in to the picture.</p>
<p>Thanks to its exquisite sensitivity, and the fact its view isn’t obscured by the Earth’s atmosphere, Kepler is capable finding planets the size of Earth, and even smaller!</p>
<p>The smallest planet Kepler has found to date is <a href="http://www.nasa.gov/home/hqnews/2013/feb/HQ_13-057_Kepler_Tiny_Planet.html">smaller than Mercury</a>, a truly amazing achievement.</p>
<h2>The leap of faith</h2>
<p>How, then, do we go from saying a planet is Earth-sized, to considering it Earth-like? </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/122240/original/image-20160512-18128-doswl7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/122240/original/image-20160512-18128-doswl7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/122240/original/image-20160512-18128-doswl7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=369&fit=crop&dpr=1 600w, https://images.theconversation.com/files/122240/original/image-20160512-18128-doswl7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=369&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/122240/original/image-20160512-18128-doswl7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=369&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/122240/original/image-20160512-18128-doswl7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=464&fit=crop&dpr=1 754w, https://images.theconversation.com/files/122240/original/image-20160512-18128-doswl7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=464&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/122240/original/image-20160512-18128-doswl7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=464&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">NASA’s planet-hunter, the Kepler Space Telescope.</span>
<span class="attribution"><a class="source" href="http://www.nasa.gov/press-release/nasa-to-announce-latest-kepler-discoveries-during-media-teleconference">NASA</a></span>
</figcaption>
</figure>
<p>Well, first, we have to work out whether Earth-sized means Earth-mass. Is the planet we’ve found rocky, metallic or gaseous? To do this, we need to find out the mass of the planet, and thereby its density.</p>
<p>This requires challenging follow-up work that is all but impossible for the smallest Kepler planets, particularly given how faint their host stars are.</p>
<p>Hence the guarded wording in the <a href="https://www.nasa.gov/press-release/nasas-kepler-mission-announces-largest-collection-of-planets-ever-discovered">NASA announcement</a> that “nearly 550 could be rocky planets like Earth, based on their size”. </p>
<p>Then we have questions about the climate and nature of the planet, and what it means to be truly Earth-like? This is a <a href="https://theconversation.com/what-makes-one-earth-like-planet-more-habitable-than-another-33479">really complicated question</a> to answer, going far beyond simply knowing a planet’s size and distance from its host.</p>
<p>A first step on that journey comes from the consideration of the habitable zone, the region around a given star where a planet like the Earth could feasibly have liquid water on its surface. </p>
<p>The exact reach of that region depends on how strict, or how relaxed your assumptions are. But it does provide a nice first cut to whittle out those planets that would simply be much too hot or much too cold (for a given set of assumptions, of course!). </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/122250/original/image-20160512-28443-e61zyk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/122250/original/image-20160512-28443-e61zyk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/122250/original/image-20160512-28443-e61zyk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=449&fit=crop&dpr=1 600w, https://images.theconversation.com/files/122250/original/image-20160512-28443-e61zyk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=449&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/122250/original/image-20160512-28443-e61zyk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=449&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/122250/original/image-20160512-28443-e61zyk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=564&fit=crop&dpr=1 754w, https://images.theconversation.com/files/122250/original/image-20160512-28443-e61zyk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=564&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/122250/original/image-20160512-28443-e61zyk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=564&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 confirmed by Kepler, new and old, that might be both rocky and move within the ‘habitable zone’ of their host stars.</span>
<span class="attribution"><span class="source">NASA Ames/N. Batalha and W. Stenzel</span></span>
</figcaption>
</figure>
<p>And this is where our knowledge of the orbital distance of the planet in question comes in to play, coupled with our understanding of its host star. Around cool, dim hosts, the habitable zone is expected to be fairly close in. Around those hosts that burn hot and bright, it would be more distant.</p>
<p>Combine our knowledge of the planet’s orbit, and of the star’s brightness, then we can estimate whether the planet could host liquid water, so long as it is something like the Earth, of course!</p>
<h2>Whittling down the sample</h2>
<p>Taking all this into consideration, the new Kepler announcement is still a fantastic achievement:</p>
<ul>
<li>1,284 new planets, of all sizes;</li>
<li>of these, almost 550 are small enough to be thought likely to be rocky planets, such as Mercury, Venus, Earth and Mars; and</li>
<li>of those 550, nine orbit their stars within the habitable zone, at just the right distance that they could, possibly, host liquid water on their surfaces.</li>
</ul>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/122202/original/image-20160512-18140-18868o4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/122202/original/image-20160512-18140-18868o4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/122202/original/image-20160512-18140-18868o4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=449&fit=crop&dpr=1 600w, https://images.theconversation.com/files/122202/original/image-20160512-18140-18868o4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=449&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/122202/original/image-20160512-18140-18868o4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=449&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/122202/original/image-20160512-18140-18868o4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=564&fit=crop&dpr=1 754w, https://images.theconversation.com/files/122202/original/image-20160512-18140-18868o4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=564&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/122202/original/image-20160512-18140-18868o4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=564&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 number of exoplanet discoveries by year.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/feature/ames/kepler/briefingmaterials160510">NASA Ames/W. Stenzel; Princeton University/T. Morton</a></span>
</figcaption>
</figure>
<p>Kepler (and other, ground-based transit searches) are strongly biased to finding large planets, very close to their host stars. </p>
<p>The closer in the planet, the shorter its orbital period, so the more transits you see, and the easier it is to be sure you’re really seeing a planet.</p>
<p>So to find even this small number of potentially Earth-like planets suggests that, in the wider scheme of things, such planets are likely common. But we can’t say for certain that any of those worlds are truly Earth-like.</p>
<p>To be sure that the planets we find are truly Earth-like, and to find planets that are good targets for the search for life elsewhere, we have to wait for the next generation of planet search programs. </p>
<h2>The future search</h2>
<p>Kepler has done an astonishing job of revealing what is out there – the first census of the exoplanet sky – but it is Kepler’s successors that will drive the search for truly Earth-like worlds.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/mpViVEO-ymc?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>Kepler’s direct successor, the Transiting Exoplanet Survey Satellite (<a href="http://tess.gsfc.nasa.gov/">TESS</a>), will launch next year. Where Kepler observed more than 100,000 faint stars in one patch of the sky, TESS will instead scan the whole sky, looking at brighter stars that are much easier to study with follow-up work.</p>
<p>Around the world, astronomers will be racing to follow up TESS’s discoveries, in a truly global endeavour. As a result, in just the next few years, we may well find the first planets that can truly be said to be Earth-like.</p><img src="https://counter.theconversation.com/content/59252/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jonti Horner 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 number of known exoplanets doubled this week to more than 3,200. But why have only a handful of these those new planets caught people’s imagination?Jonti Horner, Vice Chancellor's Senior Research Fellow, University of Southern QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/570862016-04-05T09:49:37Z2016-04-05T09:49:37ZWhy X-ray astronomers are anxious for good news from troubled Hitomi satellite<figure><img src="https://images.theconversation.com/files/117014/original/image-20160331-28476-jgxn33.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Artist's illustration of Hitomi.</span> <span class="attribution"><a class="source" href="http://astro-h.isas.jaxa.jp/en/gallery-en/">JAXA, Akihiro Ikeshita</a></span></figcaption></figure><p>On February 16, the Japanese Space Agency (JAXA) successfully <a href="http://www.space.com/32397-hitomi-x-ray-astronomy-satellite-launched-by-jaxa-video.html">launched</a> the <a href="http://global.jaxa.jp/projects/sat/astro_h/">ASTRO-H satellite</a> from Tanegashima Space Center in Japan. The space telescope named Hitomi – “pupil” in Japanese – carried with it the hopes and dreams of astrophysicists from around the world.</p>
<p>Hitomi carried a <a href="http://global.jaxa.jp/projects/sat/astro_h/instruments.html">number of scientific instruments</a>, but the most revolutionary was a device called an X-ray microcalorimeter. Astrophysicists around the world were waiting with excitement for the first observations with this instrument, which was designed to see things like the million-degree gas sloshing around galaxy clusters stirred by relativistic jets from supermassive black holes.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"714103414225960960"}"></div></p>
<p>But before anyone could see those first data from Hitomi, a possibly fatal misfortune struck. On March 26, while the spacecraft was executing its first test observations in orbit, JAXA lost contact. The U.S. Joint Space Operation Center detected five pieces of debris in the area and Hitomi’s orbit suddenly changed. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"714577410503655425"}"></div></p>
<p>What happened? We don’t know. It’s possible that a piece of space junk, or perhaps a micrometeorite, hit the spacecraft. Or maybe an onboard piece of equipment – a battery, a piece of scientific payload – failed and exploded. Signs point to the latter, since the spacecraft appears to be rapidly spinning. If an explosion caused a leak allowing, say, coolant to escape, this would spin up the spacecraft.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/117311/original/image-20160404-27139-bjyod3.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/117311/original/image-20160404-27139-bjyod3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/117311/original/image-20160404-27139-bjyod3.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=321&fit=crop&dpr=1 600w, https://images.theconversation.com/files/117311/original/image-20160404-27139-bjyod3.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=321&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/117311/original/image-20160404-27139-bjyod3.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=321&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/117311/original/image-20160404-27139-bjyod3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=404&fit=crop&dpr=1 754w, https://images.theconversation.com/files/117311/original/image-20160404-27139-bjyod3.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=404&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/117311/original/image-20160404-27139-bjyod3.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=404&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Astronomers use all sorts of electromagnetic radiation to learn about the universe – but X-ray spectra remain elusive.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:EM_spectrum.svg">Philip Ronan</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>X-ray astronomy dreams</h2>
<p><a href="https://en.wikipedia.org/wiki/Astronomical_spectroscopy">Astronomers use the electromagnetic spectrum</a> – including visible or infrared light – to study stars, planets, galaxies and the universe as a whole. They have long used prisms and <a href="https://en.wikipedia.org/wiki/Grism">grisms</a> to split the light into its components. Rather than just taking images, this spectroscopy allows astrophysicists to study the composition of objects in space and the conditions of the material that is emitting the light, including whether and how it moves around. Optical spectroscopy, for example, lets astronomers see how the stars in a galaxy move around and how old they are.</p>
<p>X-rays are near the far end of the eletromagnetic spectrum beyond the farthest ultraviolet, but not as far as <a href="https://en.wikipedia.org/wiki/Gamma_ray">Gamma rays</a>.</p>
<p>Thanks to our atmosphere, X-rays from space don’t reach us at the Earth’s surface. That’s actually good news, since we’d all be in trouble: being constantly bombarded by X-rays leads to DNA damage, cancer and worse. But this also means we need to go to space to see X-rays from the cosmos. Astrophysicists have long wanted to put an X-ray high-resolution spectrograph into space – but the goal has so far remained elusive. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/117010/original/image-20160331-28436-m4xerr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/117010/original/image-20160331-28436-m4xerr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/117010/original/image-20160331-28436-m4xerr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=579&fit=crop&dpr=1 600w, https://images.theconversation.com/files/117010/original/image-20160331-28436-m4xerr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=579&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/117010/original/image-20160331-28436-m4xerr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=579&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/117010/original/image-20160331-28436-m4xerr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=728&fit=crop&dpr=1 754w, https://images.theconversation.com/files/117010/original/image-20160331-28436-m4xerr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=728&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/117010/original/image-20160331-28436-m4xerr.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">Perseus cluster of galaxies as seen by the Chandra X-ray Observatory. The X-rays come from million-degree gases around the galaxy cluster. Giant bubbles and cavities show where the supermassive black hole blasted energy into the gas.</span>
<span class="attribution"><a class="source" href="http://chandra.harvard.edu/photo/2005/perseus/">NASA/CXC/IoA/A.Fabian et al.</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>X-ray astronomy got its start in the 1950s and ‘60’s with the first X-ray telescopes being launched on sounding rockets and balloons. Space telescopes followed, and with these, astronomers could take X-ray images or low-resolution spectra and made amazing discovery after discovery: the first black hole in our Milky Way galaxy; clusters of galaxies bathed in the glow of million-degree gas; all the way to a mysterious X-ray “background.” Soon after its launch in 1999, the <a href="http://chandra.harvard.edu/xray_sources/background.html">Chandra X-ray Observatory finally resolved</a> that X-ray background into a multitude of growing supermassive black holes in the early universe. </p>
<p>But the history of X-ray spectroscopic measurements in space is somewhat star-crossed. Before Hitomi was ASTRO-EII, known as [Suzaku](https://en.wikipedia.org/wiki/Suzaku_(satellite). Suzaku carried an X-ray microcalorimeter, but just a few weeks after launch, the instrument’s cooling system suffered a series of failures and lost all its coolant. Before that came ASTRO-E, which was lost during launch in 2000 when its M-V-4 rocket failed. And before that, NASA planned to fly an X-ray microcalorimeter on a mission called <a href="http://doi.org/10.1073/pnas.0913067107">AXAF-S</a>, which got canceled. </p>
<h2>Visions of the hot and energetic universe</h2>
<p>With a true high-resolution X-ray spectrograph in space we could finally see so much: we could see the motion, the ebb and flow, of million-degree gas sloshing around galaxy clusters as the supermassive black hole in the galaxy at the center of the cluster shoots unimaginable amounts of energy into it with its relativistic jets. We could watch the final gasps of matter as it falls into a feeding quasar, and see the distortion of spacetime itself due to Einstein’s general relativity. We could search for the “missing matter” which we believe must lurk in the vicinity of galaxies.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/117011/original/image-20160331-28462-ihezi0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/117011/original/image-20160331-28462-ihezi0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/117011/original/image-20160331-28462-ihezi0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/117011/original/image-20160331-28462-ihezi0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/117011/original/image-20160331-28462-ihezi0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/117011/original/image-20160331-28462-ihezi0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/117011/original/image-20160331-28462-ihezi0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/117011/original/image-20160331-28462-ihezi0.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">Artist’s conception of the ATHENA X-ray observatory.</span>
<span class="attribution"><a class="source" href="http://x-ifu-resources.irap.omp.eu/PUBLIC/OTHERS/HEU_THEME/ap_presentation_static_final.pdf">ATHENA/ESA</a></span>
</figcaption>
</figure>
<p>The next chance to fly such an instrument isn’t for a while. Astronomers can next pin their hopes on the <a href="http://sci.esa.int/ixo/48729-about-athena/">ATHENA satellite</a>, which the European Space Agency has selected as a flagship large-class mission. ATHENA will carry two X-ray instruments, a <a href="http://athena2.irap.omp.eu/spip.php?article18">Wide Field Imager</a> for taking large X-ray images of the sky, and a true <a href="http://x-ifu.irap.omp.eu/">X-ray calorimeter</a> which will let us do high-resolution X-ray spectroscopy.</p>
<p>But ATHENA is currently not slated to launch until 2028, and no spacecraft has ever launched on time.</p>
<h2>In space, no one can hear you ping</h2>
<p>There is still hope for Hitomi: it may be only “mostly dead,” On March 30, JAXA received two pings from the damaged satellite. This means that at least some onboard systems were still running. Perhaps over a few months, <a href="http://spacenews.com/jaxa-believes-still-possible-to-recover-hitomi/">Hitomi can be recovered</a> and still do science. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"715266412684533760"}"></div></p>
<p>JAXA has an incredible record in saving troubled spacecraft: they lost and reestablished contact with <a href="https://en.wikipedia.org/wiki/Hayabusa">Hayabusa</a> as it was trying to land on an asteroid, and when [Akatsuki](https://en.wikipedia.org/wiki/Akatsuki_(spacecraft) failed to enter its planned orbit around Venus, JAXA spent five years flying it through the solar system for a second, successful attempt.</p>
<p>The good news is that before its troubles, Hitomi <a href="http://gizmodo.com/japan-s-lost-black-hole-satellite-just-reappeared-and-n-1768036648">did take some observations and sent them back to Earth</a>… enough to amaze astrophysicists, but far too little to answer all the questions we have.</p><img src="https://counter.theconversation.com/content/57086/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kevin Schawinski receives funding from the Swiss National Science Foundation. He is part of two science working groups for the ATHENA mission.</span></em></p>Astronomers were looking forward to the first high-res X-ray spectra from space, and all they would tell us about the cosmos. But unknown disaster seems to have befallen the Japanese satellite.Kevin Schawinski, Assistant Professor of Galaxy & Black Hole Astrophysics, Swiss Federal Institute of Technology ZurichLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/549632016-02-25T04:27:12Z2016-02-25T04:27:12ZSee the cosmos with X-ray vision: Japan’s new Hitomi space telescope<figure><img src="https://images.theconversation.com/files/112287/original/image-20160222-25876-fnnjy7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">An artist's impression of the ASTRO-H telescope.</span> <span class="attribution"><a class="source" href="http://astro-h.isas.jaxa.jp/en/gallery-en/">JAXA/Akihiro Ikeshita</a></span></figcaption></figure><p>In June 1962, an <a href="http://airandspace.si.edu/collections/artifact.cfm?object=nasm_A19760034000">Aerobee 150</a> sounding-rocket blasted above the Earth’s atmosphere from the White Sands Missile Range in the United States of America. During its five-minute flight, the small research craft aimed to detect X-rays fluorescing from the moon. What it found instead would take a decade to explain.</p>
<p>X-rays are an extremely high-energy form of <a href="https://theconversation.com/let-there-be-light-celebrating-the-theory-of-electromagnetism-35723">electromagnetic radiation</a>. While visible light, from violet to red, has a wavelength of between 400 and 700 nanometers, X-ray wavelengths stretch from only 0.1 to 10 nanometers.</p>
<p>Radiation from the sun extends over both spectrums, but the energy in X-rays is a millionth of that emitted in visible light. The X-rays that reach the Earth are unable to penetrate through our atmosphere, so exploration of cosmic sources needs to be done from space.</p>
<p>Despite being a hundred times more sensitive than previous attempts, no one expected the X-ray detector on board the Aerobee 150 to see many cosmic X-ray sources. Even if our nearest star, Sirius, emitted X-rays as luminous as its visible light (unlikely given the sun’s 1:1,000,000 ratio), it was still far too dim to be seen. </p>
<p>Instead, the rocket was hoping to see the moon’s fluorescence due to the incident X-rays from the sun. But the data rolled in to reveal another source in the sky.</p>
<h2>A mysterious source</h2>
<p>Named <a href="http://www.britannica.com/topic/Scorpius-X-1">Scorpius X-1</a>, this X-ray source was so strong that if its ratio to visible light had matched that of the sun, its brightness would have rivalled the moon from its position 9,000 light years away. This was a whole new type of cosmic engine and marked the birth of X-ray astronomy.</p>
<p>Scorpius X-1 would eventually reveal itself to be a binary of two stars in close orbit. One member of the pair had reached the end of its life and collapsed to form an immensely dense object known as a <a href="http://astronomy.swin.edu.au/cosmos/N/Neutron+Star">neutron star</a>.</p>
<p>Its strong gravity was pulling gas off its stellar twin, which gained energy as it descended towards the neutron star, like a stone speeding up as it drops from a tall building. The energy was heating the gas to millions of degrees, causing it to radiate X-rays.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/111991/original/image-20160218-1276-1irw3k7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/111991/original/image-20160218-1276-1irw3k7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/111991/original/image-20160218-1276-1irw3k7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/111991/original/image-20160218-1276-1irw3k7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/111991/original/image-20160218-1276-1irw3k7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=423&fit=crop&dpr=1 754w, https://images.theconversation.com/files/111991/original/image-20160218-1276-1irw3k7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=423&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/111991/original/image-20160218-1276-1irw3k7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=423&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Galaxy cluster 3C295 in x-ray (left) and optical (right).</span>
<span class="attribution"><span class="source">NASA/CXC/SAO and NASA/HST/A.Dressier</span></span>
</figcaption>
</figure>
<p>X-ray astronomy moved from short-lived rockets to satellite observatories over the two decades following the Aerobee launch. NASA launched its <a href="http://heasarc.gsfc.nasa.gov/docs/einstein/heao2.html">Einstein observatory</a> in 1978, and in 1979, Japan launched the first of its X-ray telescopes, <a href="http://heasarc.gsfc.nasa.gov/docs/hakucho/hakucho.html">Hakucho</a>.</p>
<p>These satellites revealed that the darkest regions in the universe were bursting with high-energy activity. The space between clusters of galaxies turned out to be filled with incredibly hot gas that contained more mass than all the cooler optically-visible matter combined.</p>
<p>Gas was seen spiralling into neutron stars like Scorpius X-1 and swirling around their even more mysterious cousins, black holes.</p>
<h2>Launch of a new telescope</h2>
<p>The intrigue of this high-energy side of our universe continues and on the evening of February 17 this year, the Japanese Aerospace Exploration Agency (<a href="http://global.jaxa.jp/">JAXA</a>) launched its sixth X-ray observatory, <a href="http://astro-h.isas.jaxa.jp/en/">Hitomi</a>. The telescope is part of an international collaboration with NASA, the European Space Agency (ESA) and a number of other countries.</p>
<p>The satellite will orbit at an altitude of 575 kilometres, taking roughly an hour and a half to circle the Earth. On board are four telescopes of two different types.</p>
<p>Two telescopes focus the soft lower energy X-rays, while the second pair focus the higher energy hard X-rays. There is also a detector for the presence of the even higher energy gamma rays. In total, this allows Hitomi to be sensitive to an impressively broad range of wavelengths between 4 nanometres to 0.002 nanometres.</p>
<p>In addition to forming images, the soft X-ray telescope can measure the strength of the received X-rays at different wavelengths. This process is known as spectrometry and is equivalent to measuring the different strength of colours in the spectrum of visible light.</p>
<p>The spectrometer on-board Hitomi is about 50 times more sensitive for spread-out sources than previous missions, making it the first satellite able to measure the spectra from objects, such as galaxy clusters, in addition to bright point sources like Scorpius X-1.</p>
<p>Such measurements will allow far more accurate values to be placed on the energy in the hot gas, revealing the dynamics of cluster interactions and star formation.</p>
<h2>A name change for Hitomi</h2>
<p>Prior to launch, the satellite telescope was designated ASTRO-H, where the “H” recognises it as JAXA’s eighth planned space observatory, six of which have been X-ray satellites.</p>
<p>On the launch day, the Japanese space agency announced the <a href="http://astro-h.isas.jaxa.jp/en/info-en/2600/">telescope’s new name was Hitomi</a>, which is Japanese for the pupil of the eye, as it will be the aperture used to explore the X-ray universe.</p>
<p>When announcing Hitomi’s new name, the agency related an ancient folktale about a painter who drew four dragons, but did not include their pupils.</p>
<blockquote>
<p>People who looked at the painting said “why don’t you paint Hitomi, it is not complete!” The painter hesitated, but people pressured him. The painter then drew Hitomi on two of the four dragons. Immediately, these dragons came to life and flew up into the sky. The two dragons without Hitomi remained still.</p>
</blockquote>
<p>Clearly, the hitomi represented the key part of the painting, as the new Hitomi telescope will surely be on understanding the high-energy universe.</p><img src="https://counter.theconversation.com/content/54963/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Elizabeth Tasker 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 universe looks very different with X-ray vision, revealing some of the most energetic interactions in our galaxy. Japan’s new Hitomi telescope will help us see these wonders.Elizabeth Tasker, Assistant Professor, Hokkaido UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/408532015-04-28T17:11:10Z2015-04-28T17:11:10ZForget the James Webb, a future high-definition telescope could probe life on exoplanets<figure><img src="https://images.theconversation.com/files/79495/original/image-20150427-18143-1addpqu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Bigger but not better than Hubble. The James Webb's primary mirror.</span> <span class="attribution"><a class="source" href="http://commons.wikimedia.org/wiki/File:James_Webb_Primary_Mirror.jpg">NASA/wikimedia</a></span></figcaption></figure><p>The <a href="http://www.jwst.nasa.gov/faq.html#partners">James Webb Space Telescope</a> will be Earth’s premier space observatory for the next decade, serving thousands of astronomers worldwide. However its scientific mission will be limited. Unlike <a href="http://hubblesite.org/">Hubble</a>, which is nearing the end of its scheduled life, the James Webb will cover a much smaller part of the electromagnetic spectrum. Instead, a proposed high-definition space telescope is the only way to image Earth-like planets orbiting others stars and study them in detail.</p>
<p>While such a project <a href="http://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=10&ved=0CFIQFjAJ&url=http%3A%2F%2Fcor.gsfc.nasa.gov%2Fcopag%2Faas_jan2015%2F129-BJWST_Path_Ahead_V6.pdf&ei=R1Y-Vfr0KM_baMbhgeAO&usg=AFQjCNEI6GIbPu_ljPNG3IrQ8NsRZPci2g&bvm=bv.91665533,d.d2s">is being studied</a> by a consortium of scientists in response to a NASA call for ideas for large future space missions, it has so far not been formally approved. But it is really urgent that we start working on this project now, because the planning timescales for large missions of this kind are long. Even if we started to build it right now, it would still not be ready before 2030 at the earliest.</p>
<h2>The limits of James Webb</h2>
<p>Hubble, in low Earth orbit since 1990, has been a great success and has demonstrated the <a href="https://theconversation.com/telescopes-on-the-ground-may-be-cheaper-but-hubble-shows-why-they-are-not-enough-40724">many advantages</a> that space telescopes have over ground-based telescopes. Its successor, the James Webb, which is due for launch in 2018, is an even larger instrument, with a <a href="http://www.esa.int/Our_Activities/Space_Science/JWST_factsheet">6m diameter mirror</a> compared to Hubble’s 2.4m. Just like Hubble, it will be able to avoid the disturbing effects of the Earth’s atmosphere.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/79497/original/image-20150427-18136-btlipv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/79497/original/image-20150427-18136-btlipv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=410&fit=crop&dpr=1 600w, https://images.theconversation.com/files/79497/original/image-20150427-18136-btlipv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=410&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/79497/original/image-20150427-18136-btlipv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=410&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/79497/original/image-20150427-18136-btlipv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=515&fit=crop&dpr=1 754w, https://images.theconversation.com/files/79497/original/image-20150427-18136-btlipv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=515&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/79497/original/image-20150427-18136-btlipv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=515&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Hubble exceeded our expectations.</span>
<span class="attribution"><a class="source" href="http://spaceflight.nasa.gov/gallery/images/shuttle/sts-125/html/s125e007066.html">NASA</a></span>
</figcaption>
</figure>
<p>Its <a href="http://www.jwst.nasa.gov/science.html">scientific mission</a> includes searching for light from the first stars and galaxies and to study the formation and evolution of galaxies. This is more easily achieved by measurements in the near-infrared, which is why it will not measure visible or ultraviolet light like Hubble. While James Webb will be able to deliver some amazing science – it will collect much more light and will be able to look deeper and farther back in time in the universe – the lack of ultraviolet measurements is a major drawback. Ultraviolet can only be observed by space telescopes like James Webb, it cannot be picked up from the ground as it is blocked by the Earth’s atmosphere. Astronomers will therefore completely lose access to UV when Hubble dies.</p>
<h2>High definition is the way forward</h2>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/79500/original/image-20150427-18156-1t06as2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/79500/original/image-20150427-18156-1t06as2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/79500/original/image-20150427-18156-1t06as2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/79500/original/image-20150427-18156-1t06as2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/79500/original/image-20150427-18156-1t06as2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/79500/original/image-20150427-18156-1t06as2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/79500/original/image-20150427-18156-1t06as2.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">
<figcaption>
<span class="caption">ET phone home. Artist’s impression of an exoplanet.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/nasablueshift/7610454178/in/photolist-7WmfrV-7WpvXw-7WpvvA-7Wmeox-7Wme1p-7WmdJx-7Wmdtx-7Wpu6s-7WptWu-7WptpG-7WpteG-7WmbJr-ciosuS-rjiMWG-jeYKFZ-cAvyTd-9G2TyE-pnW2gi-99svVN-9n4kS1-f7HP3d-eCdAvK-gJJZPV-pywEXq-psB7Ko-dcT1mj-9ZSYDL-83DxQi-mCPCtX-i62xVi-pK5KjY-psB7UG-dAWSrZ-9hCPX3-cStrkC-eWfRmP-qwdYpq-79wyDN-rzBu5k-krz5JB-e1kfxg-cPbN1J-dMdqLS-91CJAH-psyxeu-psyxjQ-pGSutW-pGSuAu-psvXdq-pstpHB">NASA/JPL-Caltech/flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>The proposed <a href="http://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=10&ved=0CFIQFjAJ&url=http%3A%2F%2Fcor.gsfc.nasa.gov%2Fcopag%2Faas_jan2015%2F129-BJWST_Path_Ahead_V6.pdf&ei=R1Y-Vfr0KM_baMbhgeAO&usg=AFQjCNEI6GIbPu_ljPNG3IrQ8NsRZPci2g&bvm=bv.91665533,d.d2s">High Definition Space Telescope</a>, which would have a 10-12m aperture, would be tuned to work in the UV and visible, as well as the infrared. </p>
<p>The aim of the NASA project is to understand the technical challenges now so that they can be solved before any construction begins. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/79597/original/image-20150428-3098-nh6d0w.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/79597/original/image-20150428-3098-nh6d0w.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=188&fit=crop&dpr=1 600w, https://images.theconversation.com/files/79597/original/image-20150428-3098-nh6d0w.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=188&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/79597/original/image-20150428-3098-nh6d0w.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=188&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/79597/original/image-20150428-3098-nh6d0w.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=236&fit=crop&dpr=1 754w, https://images.theconversation.com/files/79597/original/image-20150428-3098-nh6d0w.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=236&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/79597/original/image-20150428-3098-nh6d0w.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=236&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The photon-counting detectors in the proposed HDST would have a higher count rate per pixel and lower noise than James Webb and Hubble.</span>
<span class="attribution"><a class="source" href="http://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CCIQFjAA&url=http%3A%2F%2Fcor.gsfc.nasa.gov%2Fcopag%2Faas_jan2015%2F129-BJWST_Path_Ahead_V6.pdf&ei=3H4_VejWOcvjaIK0gJgN&usg=AFQjCNEI6GIbPu_ljPNG3IrQ8NsRZPci2g&bvm=bv.91665533,d.d2s">AURA/NASA presentation</a></span>
</figcaption>
</figure>
<p>A facility would be a general, all-purpose observatory that would deliver some amazing and often unexpected science. However, the most compelling case for this telescope and one of the most exciting pieces of science that can be conceived, I believe, is the ability to image tens of Earth-like planets orbiting others stars and study them in detail. By looking at the chemical signatures in their atmospheres, it will be possible to work out if life exists and understand how common it is in our galaxy.</p>
<p>To do this, the telescope would be fitted with a disk to block the bright surface of stars, which would allow direct imaging of exoplanets. The group studying the telescope says most of the technologies needed for the mission are already being developed as part of other NASA programmes. The telescope could therefore be credibly be put forward to NASA’s <a href="http://science.nasa.gov/earth-science/decadal-surveys/">Decadal Survey</a> in 2020, which will identify and prioritise scientific questions and observations.</p>
<p>In the meantime, while we prepare for this over the next couple of decades, we should consider going back to Hubble with the next generation of human-carrying space vehicles, such as NASA’s Orion capsule, and service it at least one more time.</p><img src="https://counter.theconversation.com/content/40853/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Martin Barstow receives funding from STFC and UKSA. However his views are his own and do not represent those of the STFC or the UKSA. He is affiliated with the Royal Astronomical Society (President). </span></em></p>It’s urgent that we turn our attention to a high definition space telescope that will allow us to directly image exoplanets.Martin Barstow, Professor of Astrophysics and Space Science, University of LeicesterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/407242015-04-27T14:33:14Z2015-04-27T14:33:14ZTelescopes on the ground may be cheaper, but Hubble shows why they are not enough<figure><img src="https://images.theconversation.com/files/79104/original/image-20150423-25578-ek0gg9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Bye, Earth telescopes! You will never reach my level.</span> <span class="attribution"><a class="source" href="http://spacetelescope.org/images/hubble_in_orbit1/">ESA</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Observatories on Earth are cheaper than telescopes in space. They are also improving rapidly – when the <a href="http://www.eso.org/public/teles-instr/e-elt/">European-Extremely Large Telescope</a> starts its observations in nine years, it will be able to provide images <a href="http://www.eso.org/sci/facilities/eelt/">16 times sharper</a> than those taken by the Hubble space telescope. But while it may seem hard to justify investment in space telescopes, the ground-breaking discoveries made by <a href="http://hubblesite.org/">Hubble</a> have taught us just how valuable they are.</p>
<p>Hubble, which was the world’s first space-based optical observatory, has made amazing discoveries in all aspects of astronomy, from flashes of aurora on planets and moons in our solar system to the evolution of galaxies billions of light years away.</p>
<p>Observations by Hubble helped determine the rate of <a href="http://www.spacetelescope.org/science/age_size/">expansion</a> of the universe in a Nobel prize-winning study. We have witnessed stars being born in nurseries like the <a href="http://hubblesite.org/newscenter/archive/releases/1995/44/">Eagle nebula</a> and exploding as <a href="http://hubblesite.org/newscenter/archive/releases/2005/21/">supernovae</a>. Hubble has also captured a <a href="http://hubblesite.org/newscenter/archive/releases/2000/20/">powerful jet</a> emerging from a black hole at the centre of another galaxy.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/79256/original/image-20150424-14562-177d7ny.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/79256/original/image-20150424-14562-177d7ny.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=613&fit=crop&dpr=1 600w, https://images.theconversation.com/files/79256/original/image-20150424-14562-177d7ny.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=613&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/79256/original/image-20150424-14562-177d7ny.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=613&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/79256/original/image-20150424-14562-177d7ny.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=770&fit=crop&dpr=1 754w, https://images.theconversation.com/files/79256/original/image-20150424-14562-177d7ny.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=770&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/79256/original/image-20150424-14562-177d7ny.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=770&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Picture of the globular cluster Messier 2, taken by Hubble.</span>
<span class="attribution"><a class="source" href="http://www.esa.int/spaceinimages/Images/2015/04/The_crammed_centre_of_Messier_22">ESA/Hubble & NASA</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>These discoveries come at a price. The Hubble mission cost <a href="http://hubblesite.org/the_telescope/hubble_essentials/quick_facts.php">$1.5 billion</a> at its launch in 1990 and the maintenance costs have also been sky-high. The eagerly-anticipated first pictures taken by Hubble were disappointingly blurry. The 2.4 m diameter mirror inside the telescope was slightly flawed so the light was not focusing correctly. Installation of an optics system to correct this problem was the target of the first Hubble servicing mission, carried out by space shuttle astronauts over five days of spacewalks in 1993. Four further servicing missions were carried out from 1997 to 2009 to upgrade and replace scientific instruments, power and guidance systems, and each mission had associated risks and expense. Since the end of NASA’s Space Shuttle programme there has been no way to carry out further servicing.</p>
<p>Space telescopes are not getting any cheaper. The successor to Hubble, the James Webb telescope, has been plagued by a number of delays and rising costs. As it prepares for launch in 2018, it will have cost about <a href="http://jwst.nasa.gov/faq_scientists.html#cost">$8bn</a> to build, launch and commission. </p>
<h2>Earth v space</h2>
<p>One significant advantage of building on the ground is that the size of the telescopes can be much larger than can be carried into space. Telescopes on our own planet have also made amazing discoveries, such as the Gemini telescope observing Jupiter’s two giant red spots <a href="http://www.gemini.edu/index.php?q=node/196">brushing past one another</a> in the planet’s southern hemisphere. The Keck observatory has detected <a href="http://www.keckobservatory.org/recent/entry/detection_of_water_vapor_in_the_atmosphere_of_a_hot_jupiter">water vapour in the atmosphere</a> of a planet orbiting another star. The European Southern Observatory telescopes tracked <a href="http://www.eso.org/public/news/eso0846/">stars orbiting the black hole</a> at the centre of our galaxy to understand the formation of the stars and their interaction with the black hole.</p>
<p>However, ground-based telescopes aren’t cheap either. Work has already begun on the <a href="https://www.eso.org/sci/facilities/eelt/site/">European Extremely Large Telescope</a>, sited in Chile’s Atacama desert, with a cost estimated to be over €1 billion and with annual operating costs of €50m. But this is still less than Hubble and James Webb. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/79259/original/image-20150424-14535-1axh1am.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/79259/original/image-20150424-14535-1axh1am.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/79259/original/image-20150424-14535-1axh1am.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/79259/original/image-20150424-14535-1axh1am.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/79259/original/image-20150424-14535-1axh1am.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/79259/original/image-20150424-14535-1axh1am.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/79259/original/image-20150424-14535-1axh1am.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">
<figcaption>
<span class="caption">Artist’s impression of the European Extremely Large Telescope.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/esoastronomy/10181869333/in/photolist-dyxMgh-eiMXuB-gvJK2g-q1MM3G-ckrzoj-n814Vk-psjHyC-6CWtwW-q5vWWk-d2E4Xq-peSeuJ-p1NkHY-mjT5hx-bH7gmP-5DRHXo-e35orX-8wCvVh-jXNaCr-iRDc16-rRBaxZ-biLviH-kbQqKC-2vVkpu-8a2JHg-dAk3K3-gsLgi6-oGwLyV-o11XTS-dCsDZq-qUBjRs-rRw85Z-5NhzDt-r1kXN-sHqv-5YeD34-aNMQZZ-fPqGHR-aNMQxx-8YysNr-8YyDcc-8YBtt9-8YyC46-8YyDna-5DMvHR-9H3sho-b7H6LZ-bDtei8-9CwToe-rvZi3k-biLwJ2">European Southern Observatory/flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>When E-ELT <a href="http://www.eso.org/public/teles-instr/e-elt/">observations start</a> in 2024, the state-of-the-art correction for atmospheric distortion will allow it to provide images 16 times sharper than those taken by Hubble. With technological advancements like this it may seem hard to justify the expense and risk of future space-based telescopes. </p>
<p>However, the simple fact is that if we choose to only observe from the ground we will make ourselves blind to a wide variety of astronomical phenomena and potential discoveries. These include some of the universe’s most energetic events, such as gamma ray bursts.</p>
<p>The main reason for this is that the atmosphere of our planet does not hold back space telescopes. While the atmosphere lets through visible light, to which our eyes are sensitive, it absorbs light at some other wavelengths so we can never see it from the ground. In addition, turbulent motion in the atmosphere blurs the light travelling through it, causing objects to twinkle and appear fuzzy. Another problem with ground-based telescopes is that they are subject to local weather conditions, and high clouds can ruin the chance of making any useful observations. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/79430/original/image-20150427-18136-1ssonx4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/79430/original/image-20150427-18136-1ssonx4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/79430/original/image-20150427-18136-1ssonx4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/79430/original/image-20150427-18136-1ssonx4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/79430/original/image-20150427-18136-1ssonx4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/79430/original/image-20150427-18136-1ssonx4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/79430/original/image-20150427-18136-1ssonx4.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">The Very Large Telescope in Chile is about to get competition from the E-ELT.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/esoastronomy/14494741911/in/photolist-o5RkMi-e35orX-nEPuie-iRDc16-oHywM9-nF6o15-mx6a38-NkGHq-eK6uUe-psjHyC-oUASgZ-dCZi2g-iZGAfm-cP251Q-cP24a5-6zAr9s-91rRzA-91oJ1v-a14a94-dAk3K3-daHxyK-cXNxJE-8cK9Fv-qxoLMF-8cNsDh-oYWdhp-cXN5kU-otKQup-6Z68Po-mwwpu9-aUhuvk-4ufwAb-dxh7au-7DHi3k-dUq43U-rnu1Vf-daHEmZ-4sokd1-6WVThT-8snb98-8sndtt-8sqwUd-8snsB6-e88hWF-72BYzS-dhQfNv-4ZLxAC-9apWLQ-8sntxB-dUq451">ESO/G. Lombardi (glphoto.it)</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>From its vantage point above the atmosphere, Hubble avoids these effects and can produce high-resolution images over a broad spectrum. The scientific value of these observations is evident in that applications by scientists for observing time on Hubble last year were oversubscribed by a factor of five. It has also been an important source of scientific papers. According to a <a href="http://www.eso.org/public/unitedkingdom/announcements/ann15014/">survey by the European Southern Observatory</a> last year, Hubble has produced between 650 and 850 papers per year since 2005 – which is far more than any of ESO’s ground-based telescopes. </p>
<h2>Complementary contributions</h2>
<p>The investment in astronomical telescopes, whether in space or on the ground, has to be justified by the scientific return – and in selecting new facilities it is fundamentally the science which drives the decision. Having worked with telescopes both on the ground and in space, I feel that science ultimately needs both. But in a world of limited funds we can’t have it all. International co-operation is therefore the key, whether it is about placing a new telescope in another country or providing an instrument for a mission led by another space agency. </p>
<p>The value of the observations made by telescopes based both on the ground and in space can be measured not just by the scientific results in understanding the near and far universe, but also in the inspiration that these images and discoveries provide.</p><img src="https://counter.theconversation.com/content/40724/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sarah Badman receives funding from the Royal Astronomical Society and the Science and Technology Facilities Council. However, her views do not represent those of the STFC.</span></em></p>Ground-based telescopes are getting bigger and better while still being cheaper than space telescopes. But the vital scientific contributions made by Hubble demonstrates why we need both.Sarah Badman, Research fellow in space physics, Lancaster UniversityLicensed as Creative Commons – attribution, no derivatives.