tag:theconversation.com,2011:/ca/topics/spectroscopy-2515/articlesSpectroscopy – The Conversation2023-09-13T07:13:57Ztag:theconversation.com,2011:article/2134582023-09-13T07:13:57Z2023-09-13T07:13:57ZSigns of life? Why astronomers are excited about carbon dioxide and methane in the atmosphere of an alien world<figure><img src="https://images.theconversation.com/files/547922/original/file-20230913-23-zphpi7.jpeg?ixlib=rb-1.1.0&rect=28%2C5%2C3805%2C2149&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">NASA / CSA / ESA / J. Olmsted (STScI) / Science: N. Madhusudhan (Cambridge University)</span></span></figcaption></figure><p>Are we alone? This question is nearly as old as humanity itself. Today, this question in astronomy focuses on finding life beyond our planet. Are we, as a species, and as a planet, alone? Or is there life somewhere else?</p>
<p>Usually the question inspires visions of weird, green versions of humans. However, life is more than just us: animals, fish, plants and even bacteria are all the kinds of things we seek signs of in space.</p>
<p>One thing about life on Earth is that it leaves traces in the chemical makeup of the atmosphere. So traces like that, which are visible from a long way away, are something we look for when we’re hunting aliens. </p>
<p>Scientists in the United Kingdom and the United States <a href="https://arxiv.org/abs/2309.05566">have just reported</a> some very interesting chemical traces in the atmosphere of a planet called K2-18b, which is about 124 light-years from Earth. In particular, they may have detected a substance which on Earth is only produced by living things. </p>
<h2>Meet exoplanet K2-18b</h2>
<p>K2-18b is an interesting exoplanet – a planet that orbits another star. Discovered in 2015 by the Kepler Space Telescope’s K2 mission, it is a type of planet called a sub-Neptune. As you probably guessed, these are smaller than Neptune in our own Solar System.</p>
<p>The planet is about eight and a half times heavier than Earth, and orbits a type of star called a red dwarf, which is much cooler than our Sun. However, K2-18b orbits much closer to its star than Neptune does – in what we call the habitable zone. This is the area that is not too hot and not too cold, where liquid water can exist (instead of freezing to ice or boiling into steam).</p>
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Read more:
<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">To search for alien life, astronomers will look for clues in the atmospheres of distant planets – and the James Webb Space Telescope just proved it's possible to do so</a>
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<p>Earth is what is called a rocky planet (for obvious reasons), but sub-Neptunes are gas planets, with much larger atmospheres containing lots of hydrogen and helium. Their atmosphere can also contain other elements.</p>
<p>Which brings us to the excitement around K2-18b. </p>
<h2>How to fingerprint an atmosphere</h2>
<p>The planet was first discovered by the Kepler Space Telescope, which was monitoring distant stars and hoping for planets to pass in front of them. When a planet does pass between us and a star, the star becomes momentarily dimmer – which is what tells us a planet is there.</p>
<p>By measuring how big the dip in brightness is, how long it takes for the planet to pass in front of the star, and how often it happens, we can work out the size and orbit of the planet. This technique is great at finding planets, but it doesn’t tell us about their atmospheres – which is a key piece of information to understand if they hold life or are habitable.</p>
<p>NASA’s James Webb Space Telescope – the big space telescope launched at the end of 2021 – has now observed and measured the atmosphere of this exoplanet. </p>
<p>The telescope did this by measuring the colour of light so finely, it can detect traces of specific atoms and molecules. This process, called spectroscopy, is like measuring the fingerprint of elements. </p>
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<a href="https://images.theconversation.com/files/547994/original/file-20230913-15-44y44s.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A chart showing the absorption of different wavelengths of light by the atmosphere of K2-18b, and which wavelengths correspond to different substances in the atmosphere." src="https://images.theconversation.com/files/547994/original/file-20230913-15-44y44s.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/547994/original/file-20230913-15-44y44s.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/547994/original/file-20230913-15-44y44s.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/547994/original/file-20230913-15-44y44s.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/547994/original/file-20230913-15-44y44s.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/547994/original/file-20230913-15-44y44s.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/547994/original/file-20230913-15-44y44s.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">The atmosphere of the exoplanet K2-18b showed strong signs of methane and carbon dioxide, as well as a weak indication of dimethyl sulfide.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/goddard/2023/webb-discovers-methane-carbon-dioxide-in-atmosphere-of-k2-18b">NASA / CSA / ESA / R. Crawford (STScI) / J. Olmsted (STScI) / N. Madhusudhan (Cambridge University)</a></span>
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<p>Each element and molecule has its own colour signature. If you can look at the colour signature, you can do a bit of detective work, and work out what elements or compounds are in the planet.</p>
<p>While the planet does not have its own light, astronomers waited for when K2-18b passed in front of its star, and measured the starlight as it went through the planet’s atmosphere, allowing the team to detect fingerprints of substances in the atmosphere.</p>
<h2>Alien marine farts?</h2>
<p>The new study found a lot of carbon dioxide and methane. This is interesting as this is like what is found on Earth, Mars, and Venus in our Solar System – rather than Neptune.</p>
<p>However, it also found a small amount of dimethyl sulfide. Dimethyl sulfide is an interesting molecule, made up of carbon, hydrogen, and sulfur.</p>
<p>On Earth, it’s generally a bit smelly. But it’s also closely linked to life.</p>
<p>The only process we know that creates dimethyl sulfide on our planet is life. In particular, marine life and plankton emit it in the form of flatulence.</p>
<p>So yes, scientists are excited by the potential idea of alien marine farts. If it is real. And linked to life.</p>
<h2>The search continues</h2>
<p>While on Earth, dimethyl sulfide is linked to life, on other planets it may somehow be related to geological or chemical processes.</p>
<p>After all, K2-18b is something like Neptune – a planet we do not really know a lot about. Just last month, researchers discovered that <a href="https://www.sciencedirect.com/science/article/abs/pii/S0019103523002440">clouds on Neptune are strongly linked</a> to the Sun’s 11-year cycle of activity. We have a lot to learn about planets and their atmospheres.</p>
<p>Also, the measurement of dimethyl sulfide is very subtle – not nearly as strong as the carbon dioxide and methane. This means more detailed measurements, to improve the strength of the signal, are required. </p>
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Read more:
<a href="https://theconversation.com/the-webb-telescope-has-released-its-very-first-exoplanet-image-heres-what-we-can-learn-from-it-189876">The Webb telescope has released its very first exoplanet image – here's what we can learn from it</a>
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<p>Other telescopes may need to join the effort. Instruments on the Very Large Telescope in Chile are able to measure the atmospheres of planets around other stars – as is a new instrument called Veloce on the Anglo Australian Telescope at Siding Spring Observatory in Australia.</p>
<p>And new space telescopes, like Europe’s PLATO which is under construction, will also help us get a better look at alien atmospheres.</p>
<p>So while the signs of dimethyl sulfide on K2-18b may not be linked to life, they are still an exciting prospect. There is plenty more to explore.</p><img src="https://counter.theconversation.com/content/213458/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Brad E Tucker receives funding from the Australian Research Council and Australian Capital Territory Government. </span></em></p>The James Webb Space Telescope has detected key carbon-bearing molecules on the potential ocean world K2-18b, including tantalising hints of a substance produced by tiny plankton on Earth.Brad E Tucker, Astrophysicist/Cosmologist, Australian National UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1940622022-11-10T19:00:47Z2022-11-10T19:00:47Z‘One of the greatest damn mysteries of physics’: we studied distant suns in the most precise astronomical test of electromagnetism yet<figure><img src="https://images.theconversation.com/files/494334/original/file-20221109-24-iwl15u.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4096%2C4096&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>There’s an awkward, irksome problem with our understanding of nature’s laws which physicists have been trying to explain for decades. It’s about electromagnetism, the law of how atoms and light interact, which explains everything from why you don’t fall through the floor to why the sky is blue. </p>
<p>Our theory of electromagnetism is arguably the best physical theory humans have ever made – but it has no answer for why electromagnetism is as strong as it is. Only experiments can tell you electromagnetism’s strength, which is measured by a number called α (aka alpha, or <a href="https://en.wikipedia.org/wiki/Fine-structure_constant">the fine-structure constant</a>).</p>
<p>The American physicist Richard Feynman, who helped come up with the theory, <a href="https://www.nature.com/articles/nphys1839">called this</a> “one of the greatest damn mysteries of physics” and urged physicists to “put this number up on their wall and worry about it”.</p>
<p>In <a href="https://doi.org/10.1126/science.abi9232">research just published in Science</a>, we decided to test whether α is the same in different places within our galaxy by studying stars that are almost identical twins of our Sun. If α is different in different places, it might help us find the ultimate theory, not just of electromagnetism, but of all nature’s laws together – the “theory of everything”.</p>
<h2>We want to break our favourite theory</h2>
<p>Physicists really want one thing: a situation where our current understanding of physics breaks down. New physics. A signal that cannot be explained by current theories. A sign-post for the theory of everything.</p>
<p>To find it, they might wait <a href="https://www.supl.org.au">deep underground in a gold mine</a> for particles of dark matter to collide with a special crystal. Or they might <a href="https://www.nature.com/articles/s41586-021-03253-4">carefully tend the world’s best atomic clocks</a> for years to see if they tell slightly different time. Or smash protons together at (nearly) the speed of light in the 27-km ring of the <a href="https://www.home.cern/science/accelerators/large-hadron-collider">Large Hadron Collider</a>.</p>
<p>The trouble is, it’s hard to know where to look. Our current theories can’t guide us. </p>
<p>Of course, we look in laboratories on Earth, where it’s easiest to search thoroughly and most precisely. But that’s a bit like the <a href="https://en.wikipedia.org/wiki/Streetlight_effect">drunk only searching for his lost keys under a lamp-post</a> when, actually, he might have lost them on the other side of the road, somewhere in a dark corner.</p>
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<a href="https://images.theconversation.com/files/494326/original/file-20221109-24-yxyyed.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A detailed rainbow spectrum with many small black lines." src="https://images.theconversation.com/files/494326/original/file-20221109-24-yxyyed.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/494326/original/file-20221109-24-yxyyed.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/494326/original/file-20221109-24-yxyyed.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/494326/original/file-20221109-24-yxyyed.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/494326/original/file-20221109-24-yxyyed.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/494326/original/file-20221109-24-yxyyed.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/494326/original/file-20221109-24-yxyyed.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">The Sun’s rainbow: sunlight is here spread into separate rows, each covering just a small range of colours, to reveal the many dark absorption lines from atoms in the Sun’s atmosphere.</span>
<span class="attribution"><a class="source" href="https://noirlab.edu/public/images/noao-sun/">N.A. Sharp / KPNO / NOIRLab / NSO / NSF / AURA</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<h2>Stars are terrible, but sometimes terribly similar</h2>
<p>We decided to look beyond Earth, beyond our Solar System, to see if stars which are nearly identical twins of our Sun produce the same rainbow of colours. Atoms in the atmospheres of stars absorb some of the light struggling outwards from the nuclear furnaces in their cores. </p>
<p>Only certain colours are absorbed, leaving dark lines in the rainbow. Those absorbed colours are determined by α – so measuring the dark lines very carefully also lets us measure α.</p>
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<a href="https://images.theconversation.com/files/494328/original/file-20221109-26-mp8e2r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A close-up image showing the Sun's bubbling atmosphere." src="https://images.theconversation.com/files/494328/original/file-20221109-26-mp8e2r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/494328/original/file-20221109-26-mp8e2r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/494328/original/file-20221109-26-mp8e2r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/494328/original/file-20221109-26-mp8e2r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/494328/original/file-20221109-26-mp8e2r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/494328/original/file-20221109-26-mp8e2r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/494328/original/file-20221109-26-mp8e2r.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"></a>
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<span class="caption">Hotter and cooler gas bubbling through the turbulent atmospheres of stars make it hard to compare absorption lines in stars with those seen in laboratory experiments.</span>
<span class="attribution"><a class="source" href="https://nso.edu/press-release/inouye-solar-telescope-first-light/">NSO / AURA / NSF</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>The problem is, the atmospheres of stars are moving – boiling, spinning, looping, burping – and this shifts the lines. The shifts spoil any comparison with the same lines in laboratories on Earth, and hence any chance of measuring α. Stars, it seems, are terrible places to test electromagnetism.</p>
<p>But we wondered: if you find stars that are very similar – twins of each other – maybe their dark, absorbed colours are similar as well. So instead of comparing stars to laboratories on Earth, we compared twins of our Sun to each other.</p>
<h2>A new test with solar twins</h2>
<p>Our team of student, postdoctoral and senior researchers, at Swinburne University of Technology and the University of New South Wales, measured the spacing between pairs of absorption lines in our Sun and 16 “solar twins” – stars almost indistinguishable from our Sun.</p>
<p>The rainbows from these stars were observed on the <a href="https://www.eso.org/sci/facilities/lasilla/telescopes/3p6.html">3.6-metre European Southern Observatory (ESO) telescope</a> in Chile. While not the largest telescope in the world, the light it collects is fed into probably the best-controlled, best-understood spectrograph: <a href="https://www.eso.org/sci/facilities/lasilla/instruments/harps.html">HARPS</a>. This separates the light into its colours, revealing the detailed pattern of dark lines. </p>
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<a href="https://theconversation.com/explainer-seeing-the-universe-through-spectroscopic-eyes-37759">Explainer: seeing the universe through spectroscopic eyes</a>
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<p>HARPS spends much of its time observing Sun-like stars to search for planets. Handily, this provided a treasure trove of exactly the data we needed.</p>
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<a href="https://images.theconversation.com/files/494330/original/file-20221109-24-kj6840.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A long-exposure photo showing stars tracing out circles in the night sky behind the silhouette of a domed telescope on a hillside." src="https://images.theconversation.com/files/494330/original/file-20221109-24-kj6840.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/494330/original/file-20221109-24-kj6840.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=402&fit=crop&dpr=1 600w, https://images.theconversation.com/files/494330/original/file-20221109-24-kj6840.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=402&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/494330/original/file-20221109-24-kj6840.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=402&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/494330/original/file-20221109-24-kj6840.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=505&fit=crop&dpr=1 754w, https://images.theconversation.com/files/494330/original/file-20221109-24-kj6840.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=505&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/494330/original/file-20221109-24-kj6840.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=505&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 ESO 3.6-metre telescope in Chile spends much of its time observing Sun-like stars to search for planets using its extremely precise spectrograph, HARPS.</span>
<span class="attribution"><a class="source" href="https://www.eso.org/public/images/potw1043a/">Iztok Bončina / ESO</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>From these exquisite spectra, we have shown that α was the same in the 17 solar twins to an astonishing precision: just 50 parts per billion. That’s like comparing your height to the circumference of Earth. It’s the most precise astronomical test of α ever performed.</p>
<p>Unfortunately, our new measurements didn’t break our favourite theory. But the stars we’ve studied are all relatively nearby, only up to 160 light years away. </p>
<h2>What’s next?</h2>
<p>We’ve recently identified new solar twins much further away, about half way to the centre of our Milky Way galaxy.</p>
<p>In this region, there should be a much higher concentration of dark matter – an elusive substance astronomers believe lurks throughout the galaxy and beyond. Like α, we know precious little about dark matter, and <a href="https://doi.org/10.1016/j.physletb.2018.11.041">some theoretical physicists</a> suggest the inner parts of our galaxy might be just the dark corner we should search for connections between these two “damn mysteries of physics”.</p>
<p>If we can observe these much more distant suns with the largest optical telescopes, maybe we’ll find the keys to the universe.</p>
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<a href="https://theconversation.com/why-do-astronomers-believe-in-dark-matter-122864">Why do astronomers believe in dark matter?</a>
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<p class="fine-print"><em><span>Michael Murphy receives funding from the Australian Research Council. </span></em></p>A new study of ‘solar twins’ shows a fundamental constant appears to be the same throughout our local galactic neighbourhood.Michael Murphy, Professor of Astrophysics, Swinburne University of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1924452022-10-21T17:04:48Z2022-10-21T17:04:48ZFour ways to spot hints of alien life using the James Webb Space Telescope<figure><img src="https://images.theconversation.com/files/490217/original/file-20221017-19-fs1i2r.jpg?ixlib=rb-1.1.0&rect=4%2C0%2C2982%2C1994&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">An artist's impression of planet Gliese 667 Cc at sunset. </span> <span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Gliese_667_Cc#/media/File:Gliese_667_Cc_sunset.jpg">ESO/L. Calçada</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>The study of exoplanets, worlds which orbit stars other than our sun, is currently being transformed <a href="https://theconversation.com/james-webb-space-telescope-how-our-launch-of-worlds-most-complex-observatory-will-rest-on-a-nail-biting-knife-edge-173619">by the new James Webb Space Telescope</a> (JWST). We will shortly gain our first insight into conditions on rocky, potentially Earth-like worlds beyond our solar system. One of these distant worlds might host life. But could we detect it?</p>
<p>We may be able to spot signs of life in the composition of the planet’s atmosphere. We can use a technique called <a href="https://theconversation.com/its-all-in-the-atmosphere-exploring-planets-orbiting-distant-stars-62034">transmission spectroscopy</a> – which divides up light by its wavelength – to search for traces of different gases in starlight as it passes through a planet’s atmosphere. </p>
<p>Some starlight-absorbing gases might indicate the presence of life on the planet. We call these biosignatures. </p>
<h2>1. Oxygen and ozone</h2>
<p>Oxygen is probably the most obvious biosignature. Plants make it, we breathe it and the rock record shows that levels in Earth’s atmosphere <a href="https://theconversation.com/earths-oxygen-has-varied-dramatically-over-time-heres-how-our-data-could-help-us-spot-alien-life-192349">changed dramatically as life evolved</a>. The oxygen that we breathe is O<sub>2</sub>, two oxygen atoms stuck together. But another configuration of oxygen, O<sub>3</sub> or ozone, could also be observed with JWST. </p>
<p>So, if we detected one or both of these gases, would it be job done? Unfortunately not. Another scenario that could produce large amounts of atmospheric oxygen is a planet undergoing a “<a href="https://theconversation.com/venus-the-trouble-with-sending-people-there-191534">runaway greenhouse effect</a>”. Once a planet is hot enough for its water ocean to evaporate, the resulting water vapour in the atmosphere contributes to a greenhouse effect – super-heating the planet to levels that aren’t compatible with life – in a feedback loop. </p>
<p>Eventually, the planet becomes hot enough for water molecules to break apart into hydrogen and oxygen. Hydrogen molecules are light and can move fast enough to easily escape the planet’s gravity, whereas the more sluggish oxygen tends to stick around, ready to be detected and trick unsuspecting astronomers. </p>
<h2>2. Phosphine and ammonia</h2>
<p>The current focus of the search for life might be mostly on exoplanets, but there have also been recent developments closer to home. Phosphine – a gas that occurs naturally in hydrogen-dominated atmospheres like those of gas giants Jupiter and Saturn – was recently <a href="https://www.liebertpub.com/doi/10.1089/ast.2018.1954">detected in the atmosphere of Venus</a>. Interestingly, phosphine is considered to <a href="https://www.liebertpub.com/doi/10.1089/ast.2018.1954">be a potential biosignature</a>.</p>
<p>On Earth, phosphine is produced by microorganisms, for example in the intestinal tracts of animals. If no life is present, we wouldn’t expect phosphine to occur in large quantities in Venus-like atmospheres, which are dominated by carbon dioxide. That said, we can’t yet rule out other sources of phosphine on Venus.</p>
<p>Foul-smelling ammonia is another potential biosignature gas, also produced by animals on Earth. Like phosphine, it is prevalent on gas giant planets, but not expected to occur on rocky worlds in the absence of life. </p>
<p>However, detecting phosphine or ammonia in the atmosphere of a distant exoplanet is likely to be challenging. Both reach tiny concentrations of only a few parts per billion on Earth. So unless our potential extraterrestrials are much stinkier than Earth’s animals, we probably won’t be spotting them any time soon.</p>
<h2>3. Methane plus carbon dioxide</h2>
<p>Individual gases that are unambiguous biosignatures are few and far between, so we might be better off looking for a winning combination if we want to detect life. Large amounts of <a href="https://www.pnas.org/doi/10.1073/pnas.2117933119">methane</a>, produced by farting animals on Earth, plus carbon dioxide would be a good hint that there is something going on. </p>
<p>If there’s enough oxygen available, then carbon much prefers to hang around with oxygen as carbon dioxide (CO<sub>2</sub>, one carbon atom and two oxygen atoms), rather than form methane (CH<sub>4</sub>, one carbon atom and four hydrogen atoms). In an oxygen-rich environment, any carbon finding itself in a methane molecule quickly ditches its hydrogen buddies in favour of a couple of spare oxygens. </p>
<figure class="align-center ">
<img alt="Cartoon showing a carbon atom leaving four hydrogen atoms and heading towards a pair of oxygen atoms, saying 'Bye!' as it leaves." src="https://images.theconversation.com/files/490485/original/file-20221018-8364-beidg3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/490485/original/file-20221018-8364-beidg3.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=339&fit=crop&dpr=1 600w, https://images.theconversation.com/files/490485/original/file-20221018-8364-beidg3.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=339&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/490485/original/file-20221018-8364-beidg3.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=339&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/490485/original/file-20221018-8364-beidg3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=426&fit=crop&dpr=1 754w, https://images.theconversation.com/files/490485/original/file-20221018-8364-beidg3.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=426&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/490485/original/file-20221018-8364-beidg3.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=426&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">When it’s available, carbon prefers the company of oxygen.</span>
<span class="attribution"><span class="source">Author's own work.</span></span>
</figcaption>
</figure>
<p>So seeing lots of both methane and carbon dioxide coexisting would suggest that something – maybe bacteria – is constantly producing methane.</p>
<h2>4. Chemical imbalances</h2>
<p>We can apply the above argument to any combination of gases that shouldn’t happily coexist. Life disrupts the chemical equilibrium (balance) of its environment because it uses chemical reactions to generate energy. </p>
<p>On Earth, oxygen is transformed into carbon dioxide, but in a different type of atmosphere, with different chemicals available, life would use other processes to achieve the same goal. Methane-producing bacteria that live around hydrothermal vents deep in Earth’s oceans, for example, harvest chemical energy from minerals and chemical compounds. Looking for imbalances allows us to be open minded about what life elsewhere might look like.</p>
<h2>What happens if we spots signals of alien life?</h2>
<p>JWST is already <a href="https://www.nature.com/articles/s41586-022-05269-w">exceeding our expectations</a> for exoplanet atmosphere observations. As powerful as it is, though, rocky planets with mild temperatures and atmospheres dominated by nitrogen or carbon dioxide are still going to be challenging to study using transmission spectroscopy. The signals we expect from these planets are much weaker than those we have successfully observed in hot gas giant atmospheres. </p>
<p>If we are lucky enough to observe starlight-absorbing gases in the atmosphere of a rocky exoplanet – <a href="https://solarsystem.nasa.gov/resources/2686/exploring-alien-worlds-with-nasas-james-webb-space-telescope-trappist-1-system/">TRAPPIST-1e</a>, for example – we still have to measure how much of these gases are present to draw meaningful conclusions. This isn’t straightforward as the signals can overlap and need to be carefully disentangled.</p>
<p>Even if we do detect and accurately measure one of our possible biosignature gases, I don’t think we could claim to have detected alien life. JWST is only just opening up a new, rich laboratory of planetary atmospheres, and as we explore no doubt we will find many of our previous assumptions are proven wrong. </p>
<p>Jumping to conclusions about aliens every time we find something unusual would be premature. A JWST biosignature detection would be an interesting hint, with the promise of a great deal more work to do. As an astronomer, that’s exciting enough for me.</p><img src="https://counter.theconversation.com/content/192445/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Joanna Barstow receives funding from the Science and Technology Faciliites Council. She is a Councillor and Trustee of the Royal Astronomical Society.</span></em></p>New telescope allows us to study the atmospheres of planets orbiting stars other than our Sun in unprecedented detail.Joanna Barstow, Ernest Rutherford Fellow, The Open UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1490462020-10-30T15:17:52Z2020-10-30T15:17:52ZA new laser technique designed to authenticate rare whisky could also detect disease<figure><img src="https://images.theconversation.com/files/366669/original/file-20201030-13-x2eoe9.jpg?ixlib=rb-1.1.0&rect=22%2C0%2C2950%2C1998&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/edinburgh-scotland-july-10-diageo-claive-120771646">Shutterstock</a></span></figcaption></figure><p>Whisky is big business in Scotland. In 2019, the golden liquid accounted for <a href="https://www.scotch-whisky.org.uk/insights/facts-figures/">75%</a> of the nation’s food and drink exports, with a value of almost <a href="https://www.scotch-whisky.org.uk/insights/facts-figures/">£5 billion</a> to the Scottish economy. Iconic bottles have sold at auction for <a href="https://www.forbes.com/sites/felipeschrieberg/2019/10/26/macallan-bottle-sells-for-19-million-and-breaks-the-world-recordagain/">over £1 million</a>. But if you are the lucky owner of such a whisky, how can you be confident that what you are buying is the genuine product? </p>
<p><a href="https://www.cambridge.org/core/journals/radiocarbon/article/using-carbon-isotopes-to-fight-the-rise-in-fraudulent-whisky/75071F4AB4D7A231B714102B0FE8F5C6">Studies have shown</a> that around one-third of rare whiskies on sale at auction may be fakes. In a <a href="https://www.bbc.co.uk/news/uk-scotland-scotland-business-41695774">well-publicised incident in 2017</a>, a collector paid a world-record £7,600 for a single dram of rare whisky, only to later discover he had been sold a knock-off. Such counterfeit drinks cost the UK economy over <a href="https://www.thedrinksbusiness.com/2018/06/the-uk-loses-218-million-every-year-from-counterfeit-wine-and-spirits/">£200m in lost revenue</a> each year, as well as damaging the reputation of sellers.</p>
<p>The problem of counterfeit alcohol is not restricted to only wealthy collectors. Several cases have been reported of people being poisoned and dying from drinking whisky containing <a href="https://scotchwhisky.com/magazine/in-depth/8308/russia-s-deadly-fake-whisky/">high levels of poisonous methanol</a>.</p>
<p>But soon these kind of problems may be a thing of the past, as <a href="https://doi.org/10.1039/D0AY01101K">our research</a> has enabled us to develop a new method that can use lasers to chemically test the authenticity of whisky, without ever opening the bottle. And crucially, the technique has the potential to measure other substances in this way, including human tissue.</p>
<h2>How does it work?</h2>
<p>When a laser beam is shone into a substance like whisky, the liquid scatters some of the light into a variety of different colours. The exact mix of colours produced is unique to the chemical make-up of the sample, and can be used like a fingerprint to identify the sample.</p>
<p>The technique of measuring this fingerprint, which gives us a detailed understanding of the interaction between the light and the atoms and molecules which make up a sample, is known as <a href="https://www.britannica.com/science/spectroscopy">spectroscopy</a>. Just like fingerprint identification of criminals, the identity of a whisky sample can be tested by cross-referencing the spectroscopic signal against a database of known samples.</p>
<p>Whisky is a particularly complex mix of chemicals, known as <a href="https://healthengine.com.au/info/congeners-in-alcoholic-beverages">congeners</a>, which give the contents of each cask a unique flavour, aroma and colour. While criminals have become increasingly sophisticated in mimicking the taste, smell and appearance of sought-after drams, to fool this system requires a sham whisky to be chemically identical to the real thing – a very, very hard thing to create.</p>
<p>We have been developing spectroscopy-based <a href="https://www.osapublishing.org/oe/abstract.cfm?uri=oe-19-23-22982">tests for whisky authenticity</a> for almost a decade. The method also works for other food and drink where counterfeiting can be a problem, such as <a href="https://journals.sagepub.com/doi/10.1177/0003702816645931">olive oil</a>, <a href="https://www.sciencedirect.com/science/article/pii/S0308814616306872">wine</a> and <a href="https://link.springer.com/article/10.1007/s12161-017-1072-2">honey</a>.</p>
<p>However, the contents are not the only source of scattered light. A common problem in all of those tests is that the glass container can produce a signal even larger than the one from the contents. </p>
<p>This is avoided in the lab by testing a sample placed in a standardised container. But if you had just spent a small fortune on the latest addition to your collection of rare whiskies, would you want us to remove and use up some of your precious purchase?</p>
<figure class="align-center ">
<img alt="A bottle of whisky with a cone-shaped laser shining through it." src="https://images.theconversation.com/files/366672/original/file-20201030-19-11hay9k.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/366672/original/file-20201030-19-11hay9k.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=686&fit=crop&dpr=1 600w, https://images.theconversation.com/files/366672/original/file-20201030-19-11hay9k.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=686&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/366672/original/file-20201030-19-11hay9k.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=686&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/366672/original/file-20201030-19-11hay9k.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=862&fit=crop&dpr=1 754w, https://images.theconversation.com/files/366672/original/file-20201030-19-11hay9k.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=862&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/366672/original/file-20201030-19-11hay9k.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=862&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A special cone-shaped laser ensures the signal from the glass bottle does not interfere with the measurement of the liquid inside.</span>
<span class="attribution"><span class="source">University of St Andrews</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Our <a href="https://doi.org/10.1039/D0AY01101K">new technique</a> was designed to overcome this challenge. Rather than illuminating the bottle with a standard laser beam, we introduced a cone-shaped piece of glass in front of the bottle to reshape the light. </p>
<p>By forming a ring of laser light on the bottle surface which is gathered into a tightly focused spot within the liquid contents, we can now place our detector so that only scattered light produced inside the bottle is collected – and any light produced by the ring on the glass misses.</p>
<p>In this way we can measure the contents (like recording an accurate fingerprint) without that annoying contribution from the container. We tested the method on whiskies from a range of distilleries, and were able to distinguish them with ease. We have also shown the method works for other spirits including vodka and gin.</p>
<h2>Other useful benefits</h2>
<p>Going beyond food and drink, all sorts of other substances can be measured in this way. Recently, our group showed that you can use a similar laser-based approach to measure <a href="https://www.nature.com/articles/s42003-020-0915-3">bacteria</a> and test their response to antibiotics.</p>
<p>Methods based on laser light offer the potential advantage of telling us the chemical make-up of what they see with high resolution and in a much cheaper and more compact set-up than an MRI scanner, providing vital information in diagnosis.</p>
<p>Laser spectroscopy gives us the chemical information but, because light usually doesn’t penetrate far into the skin, this is currently limited to diagnosis close to the surface. We plan to test our new laser-shaping method to see if it will allow light to penetrate deeper into tissue and potentially chemically detect cancer inside the body.</p>
<p>For now, spectroscopy offers a potentially simple way to test alcohols, when compared with other lab-based methods such as <a href="https://www.cambridge.org/core/journals/radiocarbon/article/using-carbon-isotopes-to-fight-the-rise-in-fraudulent-whisky/75071F4AB4D7A231B714102B0FE8F5C6">radiocarbon dating</a>. It is non-destructive, and as our work demonstrates, can be performed without even opening the original container.</p>
<p>The simplicity of the approach suggests devices could be easily manufactured for widespread use. In future, we hope connoisseurs will be able to authenticate their expensive alcohol at the point of purchase, without wasting a drop.</p><img src="https://counter.theconversation.com/content/149046/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Graham D Bruce receives funding from the UK Engineering and Physical Sciences Research Council. </span></em></p><p class="fine-print"><em><span>Kishan Dholakia receives funding from the UK Engineering and Physical Sciences Research Council.</span></em></p>A new laser technique that measures the chemical make-up of whisky may help fight cancers.Graham D Bruce, Senior Researcher & Laboratory Manager, University of St AndrewsKishan Dholakia, Professor of Physics and Astronomy, University of St AndrewsLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1460932020-09-14T19:50:32Z2020-09-14T19:50:32ZLife on Venus? Traces of phosphine may be a sign of biological activity<figure><img src="https://images.theconversation.com/files/357810/original/file-20200914-14-hd6f47.jpg?ixlib=rb-1.1.0&rect=6%2C18%2C1376%2C1364&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">JAXA / ISAS / DARTS / Damia Bouic</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>The discovery that the atmosphere of Venus absorbs a precise frequency of microwave radiation has just <a href="https://doi.org/10.1038/s41550-020-1174-4">turned planetary science on its head</a>. An international team of scientists used radio telescopes in Hawaii and Chile to find signs that the clouds on Earth’s neighbouring planet contain tiny quantities of a molecule called phosphine.</p>
<p>Phosphine is a compound made from phosphorus and hydrogen, and on Earth its only natural source is tiny microbes that live in oxygen-free environments. It’s too early to say whether phosphine is also a sign of life on Venus – but no other explanation so far proposed seems to fit. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/ePoDG00VydE?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">This video shows how methane was detected in the atmosphere of Mars. The process is the same for finding phosphine on Venus.</span></figcaption>
</figure>
<h2>What makes an atmosphere?</h2>
<p>The molecular makeup of a planet’s atmosphere normally depends on what its parent star is made of, the planet’s position in its star’s system, and the chemical and geological processes that take place given these conditions. </p>
<p>There is phosphine in the atmospheres of Jupiter and Saturn, for example, but there it’s not a sign of life. Scientists think it is formed in the deep atmosphere at high pressures and temperatures, then dredged into the upper atmosphere by a strong convection current. </p>
<p>Although phosphine quickly breaks down into phosphorus and hydrogen in the top clouds of these planets, enough lingers – 4.8 parts per million – to be observable. The phosphorus may be what gives clouds on Jupiter a reddish tinge.</p>
<p>Things are different on a rocky planet like Venus. The new research has found fainter traces of phosphine in the atmosphere, at 20 parts per billion. </p>
<p>Lightning, clouds, volcanoes and meteorite impacts might all produce some phosphine, but not enough to counter the rapid destruction of the compound in Venus’s highly oxidising atmosphere. The researchers considered all the chemical processes they could think of on Venus, but none could explain the concentration of phosphine. What’s left? </p>
<p>On Earth, phosphine is only produced by microbial life (and by various industrial processes) – and the concentration in our atmosphere is in the parts per trillion range. The much higher concentration on Venus cannot be ignored. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/we-asked-astronomers-are-we-alone-in-the-universe-the-answer-was-surprisingly-consistent-132088">We asked astronomers: are we alone in the Universe? The answer was surprisingly consistent</a>
</strong>
</em>
</p>
<hr>
<h2>Signs of life?</h2>
<p>To determine whether the phosphine on Venus is really produced by life, chemists and geologists will be trying to identify other reactions and processes that could be alternative explanations. </p>
<p>Meanwhile, biologists will be trying to better understand the microbes that live in Venus-like conditions on Earth – high temperatures, high acidity, and high levels of carbon dioxide – and also ones that produce phosphine. </p>
<p>When Earth microbes produce phosphine, they do it via an “anaerobic” process, which means it happens where no oxygen is present. It has been observed in places such as activated sludge and sewage treatment plants, but the exact collection of microbes and processes is not well understood. </p>
<p>Biologists will also be trying to work out whether the microbes on Earth that produce phosphine could conceivably do it under the harsh Venusian conditions. If there is some biological process producing phosphine on Venus, it may be a form of “life” very different from what we know on Earth.</p>
<p>Searches for life beyond Earth have often skipped over Venus, because its surface temperature is around 500°C and the atmospheric pressure is almost 100 times greater than on Earth. Conditions are <a href="https://www.liebertpub.com/doi/10.1089/ast.2017.1783">more hospitable for life</a> as we know it about 50 kilometres off the ground, although there are still vast clouds of sulfuric acid to deal with.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-the-idea-of-alien-life-now-seems-inevitable-and-possibly-imminent-115643">Why the idea of alien life now seems inevitable and possibly imminent</a>
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<h2>Molecular barcodes</h2>
<p>The researchers found the phosphine using spectroscopy, which is the study of how light interacts with molecules. When sunlight passes through Venus’s atmosphere, each molecule absorbs very specific colours of this light. </p>
<p>Using telescopes on Earth, we can take this light and split it into a massive rainbow. Each type of molecule present in Venus’ atmosphere produces a distinctive pattern of dark absorption lines in this rainbow, like an identifying barcode. </p>
<figure class="align-center ">
<img alt="A rainbow image of stripes fading from red through the visible spectrum to blue, with narrow black lines." src="https://images.theconversation.com/files/357805/original/file-20200914-14-2hyaac.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/357805/original/file-20200914-14-2hyaac.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/357805/original/file-20200914-14-2hyaac.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/357805/original/file-20200914-14-2hyaac.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/357805/original/file-20200914-14-2hyaac.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/357805/original/file-20200914-14-2hyaac.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/357805/original/file-20200914-14-2hyaac.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 full visible spectrum of sunlight, showing the dark ‘barcodes’ that indicate the presence of different atoms and molecules.</span>
<span class="attribution"><a class="source" href="https://solarsystem.nasa.gov/resources/390/the-solar-spectrum/">N.A.Sharp, NOAO/NSO/Kitt Peak FTS/AURA/NSF</a></span>
</figcaption>
</figure>
<p>This barcode is not always strongest in visible light. Sometimes it can only be detected in the parts of the electromagnetic spectrum that are invisible to the human eye, such as UV rays, microwave, radio waves and infrared. </p>
<p>The barcode of carbon dioxide, for example, is most evident in the infrared region of the spectrum. </p>
<p>While phosphine on Jupiter was first detected in infrared, for Venus observations astronomers used radio telescopes: the <a href="https://www.almaobservatory.org/en/home/">Atacama Large Millimeter/submillimeter Array</a> (ALMA) and <a href="https://www.eaobservatory.org/jcmt/about-jcmt/">James Clerk Maxwell Telescope</a> (JCMT), which can detect the barcode of phosphine in millimetre wavelengths.</p>
<h2>New barcodes, new discoveries</h2>
<p>The discovery of phosphine on Venus relied not only on new observations, but also a more detailed knowledge of the compound’s barcode. Accurately predicting the barcode of phosphine across all relevant frequencies took <a href="http://www.tampa.phys.ucl.ac.uk/ftp/eThesis/ClaraSousaSilva2015.pdf">the whole PhD</a> of astrochemist Clara Sousa-Silva in the <a href="https://www.ucl.ac.uk/exoplanets/research/spectroscopy-exoplanets">ExoMol group</a> at University College London in 2015. </p>
<p>She used computational quantum chemistry – basically putting her molecule into a computer and solving the equations that describe its behaviour – to predict the strength of the barcode at different colours. She then tuned her model using available experimental data before making the <a href="https://arxiv.org/abs/1410.2917">16.8 billion lines of phosphine’s barcode</a> available to astronomers. </p>
<p>Sousa-Silva originally thought her data would be used to study Jupiter and Saturn, as well as weird stars and distant “hot Jupiter” exoplanets. </p>
<p>More recently, she led the detailed consideration of <a href="https://arxiv.org/abs/1910.05224">phosphine as a biosignature</a> – a molecule whose presence implies life. This analysis demonstrated that, on small rocky exoplanets, phosphine should not be present in observable concentrations unless there was life there as well. </p>
<p>But she no doubt wouldn’t have dreamed of a phone call from an astronomer who has discovered phosphine on our nearest planetary neighbour. With phosphine on Venus, we won’t be limited to speculating and looking for molecular barcodes. We will be able to send probes there and hunt for the microbes directly.</p><img src="https://counter.theconversation.com/content/146093/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>The discovery of phosphine in the acidic clouds of Venus can’t be explained by any known chemical or geological processes.Laura McKemmish, Lecturer, UNSW SydneyBrendan Paul Burns, Senior Lecturer, UNSW SydneyLucyna Kedziora-Chudczer, Program Manager / Adjunct Research Fellow, Swinburne University of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1376302020-05-04T15:01:19Z2020-05-04T15:01:19ZHydrogen-breathing aliens? Study suggests new approach to finding extraterrestrial life<figure><img src="https://images.theconversation.com/files/331738/original/file-20200430-42942-o1p5xu.png?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">An exoplanet and its atmosphere pass in front of its star (artist's impression, from an imaginary point near to the planet).</span> <span class="attribution"><a class="source" href="https://www.astrobio.net/also-in-news/new-nasa-study-improves-search-habitable-worlds/">NASA Goddard Space Flight Center</a></span></figcaption></figure><p>The first time we find evidence of life on a planet orbiting another star (an <a href="https://theconversation.com/more-than-1-000-new-exoplanets-discovered-but-still-no-earth-twin-59274">exoplanet</a>), it is probably going to be by analysing the gases in its atmosphere. With the number of known Earth-like planets growing, we could soon discover gases in an exoplanet’s atmosphere that are associated with life on Earth. </p>
<p>But what if alien life uses somewhat different chemistry to ours? A new study, <a href="https://www.nature.com/articles/s41550-020-1069-4">published in Nature Astronomy</a>, argues that our best chances of using atmospheres to find evidence of life is to broaden our search from focusing on planets like our own to include those with a hydrogen atmosphere.</p>
<p>We can probe the atmosphere of an exoplanet when it passes in front of its star. When such a transit happens, the star’s light has to pass through the planet’s atmosphere to reach us and some of it is absorbed as it goes. Looking at the star’s spectrum – its light broken down according to its wavelength – and working out what light is missing because of the transit reveals which gases the atmosphere consists of. Documenting exoplanet atmospheres is one of the goals of the much-delayed <a href="https://www.jwst.nasa.gov/">James Webb Space Telescope</a>.</p>
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Read more:
<a href="https://theconversation.com/exoplanets-how-we-used-chemistry-to-identify-the-worlds-most-likely-to-host-life-100897">Exoplanets: how we used chemistry to identify the worlds most likely to host life</a>
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<p>If we were to find an atmosphere that has a different chemical mix to what we would expect, one of the simplest explanations would be that it is maintained that way by living processes. That is the case on Earth. Our planet’s atmosphere contains methane (CH₄), which naturally reacts with oxygen to make carbon dioxide. But the methane is kept topped up by biological processes.</p>
<p>Another way to look at this is that the oxygen wouldn’t be there at all had it not been liberated from carbon dioxide by photosynthetic microbes during the so-called <a href="https://earthhow.com/atmosphere-history/">great oxygenation event</a> that began about 2.4 billion years ago. </p>
<h2>Look beyond oxygen atmospheres</h2>
<p>The authors of the new study argue that we should start investigating worlds larger than the Earth whose atmospheres are dominated by hydrogen. These may not have any free oxygen, because hydrogen and oxygen make a highly flammable mixture.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/331735/original/file-20200430-42946-ftcaed.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/331735/original/file-20200430-42946-ftcaed.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=711&fit=crop&dpr=1 600w, https://images.theconversation.com/files/331735/original/file-20200430-42946-ftcaed.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=711&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/331735/original/file-20200430-42946-ftcaed.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=711&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/331735/original/file-20200430-42946-ftcaed.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=893&fit=crop&dpr=1 754w, https://images.theconversation.com/files/331735/original/file-20200430-42946-ftcaed.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=893&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/331735/original/file-20200430-42946-ftcaed.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=893&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">The hydrogen-filled Hindenberg airship destroyed by fire in 1937. Such a fire could not happen on a world with an oxygen-free hydrogen atmosphere.</span>
<span class="attribution"><span class="source">Murray Becker/Associated Press</span></span>
</figcaption>
</figure>
<p>Hydrogen is the lightest of all molecules and escapes to space easily. For a rocky planet to have gravity strong enough to hang on to a hydrogen atmosphere, it needs to be a “super-Earth” with a mass between about two and ten times the Earth’s. The hydrogen could either have been captured directly from the gas cloud where the planet grew, or have been released later by a chemical reaction between iron and water. </p>
<p>The density of a hydrogen-dominated atmosphere decreases about 14 times less rapidly the higher up you go than in an atmosphere dominated by nitrogen like the Earth’s. This makes for a 14-times greater envelope of atmosphere surrounding the planet, making it easy to spot in the spectra data. The greater dimensions would also improve our chances of observing such an atmosphere by direct imaging with an optical telescope.</p>
<h2>Hydrogen-breathing in the lab</h2>
<p>The authors carried out laboratory experiments in which they demonstrated that the bacterium <em>E. coli</em> (billions of which live in your intestines) can survive and multiply under a hydrogen atmosphere in the total absence of any oxygen. They demonstrated the same for a variety of yeast. </p>
<p>Although this is interesting, it does not add much weight to the argument that life could flourish under a hydrogen atmosphere. We already know of many microbes within the Earth’s crust that survive by metabolising hydrogen, and there is even a multicellular organism that <a href="http://www.bbc.com/earth/story/20170125-there-is-one-animal-that-seems-to-survive-without-oxygen">spends all its life in an oxygen-free zone</a> on the floor of the Mediterranean. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/331765/original/file-20200430-42935-1ymg3b9.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/331765/original/file-20200430-42935-1ymg3b9.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=793&fit=crop&dpr=1 600w, https://images.theconversation.com/files/331765/original/file-20200430-42935-1ymg3b9.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=793&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/331765/original/file-20200430-42935-1ymg3b9.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=793&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/331765/original/file-20200430-42935-1ymg3b9.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=996&fit=crop&dpr=1 754w, https://images.theconversation.com/files/331765/original/file-20200430-42935-1ymg3b9.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=996&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/331765/original/file-20200430-42935-1ymg3b9.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=996&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Spinoloricus, a tiny but multicellular organism that apparently requires no oxygen to live. Scale bar is 50 micrometres.</span>
<span class="attribution"><span class="source">Roberto Danovaro, Antonio Dell'Anno, Antonio Pusceddu, Cristina Gambi, Iben Heiner & Reinhardt Mobjerg Kristensen</span></span>
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</figure>
<p>Earth’s atmosphere, which started out without oxygen, is unlikely ever to have had more than 1% hydrogen. But early life may have had to metabolise by reacting hydrogen with carbon to form methane, rather than by reacting oxygen with carbon to form carbon dioxide, as humans do.</p>
<h2>Biosignature gases</h2>
<p>The study did make an important discovery though. The researchers demonstrated that there is an “astonishing diversity” of dozens of gases produced by products in <em>E. coli</em> living under hydrogen. Many of these, such as dimethylsilfide, carbonyl sulfide and isoprene, could be detectable “biosignatures” in a hydrogen atmosphere. This boosts our chances of recognising life signs at an exoplanet – you have to know what to look for.</p>
<p>That said, metabolic processes that use hydrogen are less efficient than those using oxygen. However, <a href="https://www.sciencefocus.com/space/could-alien-life-breathe-a-gas-other-than-oxygen/">hydrogen breathing life</a> is already an established concept so far as astrobiologists are concerned. Sentient hydrogen breathers have even made appearances in some rationally-based science fiction, such as the <a href="http://www.davidbrinfans.org/2016/06/26/timeline-history-of-the-five-galaxies/">Uplift novels of David Brin</a>. </p>
<p>The authors of the new study also point out that molecular hydrogen in sufficient concentration can act as a greenhouse gas. This could keep a planet’s surface warm enough for liquid water, and hence surface life, further from its star than would otherwise be the case. </p>
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Read more:
<a href="https://theconversation.com/twin-civilisations-how-life-on-an-exoplanet-could-spread-to-its-neighbour-51638">Twin civilisations? How life on an exoplanet could spread to its neighbour</a>
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<p>The authors shy away from considering the chances of finding life in giant gas planets like Jupiter. Even so, by expanding the pool of habitable worlds to include super-Earths with hydrogen-rich atmospheres, they have potentially doubled the number of bodies we could probe to find those first elusive signs of extraterrestrial life.</p><img src="https://counter.theconversation.com/content/137630/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Rothery is Professor of Planetary Geosciences at the Open University. He is co-leader of the European Space Agency's Mercury Surface and Composition Working Group, and a Co-Investigator on MIXS (Mercury Imaging X-ray Spectrometer) that is now on its way to Mercury on board the European Space Agency's Mercury orbiter BepiColombo. He has received funding from the UK Space Agency and the Science & Technology Facilities Council for work related to Mercury BepiColombo, and is currently funded by the European Commission under its Horizon 2020 programme for work on planetary geological mapping (776276 Planmap). He is author of Planet Mercury - from Pale Pink Dot to Dynamic World (Springer, 2015), Moons: A Very Short Introduction (Oxford University Press, 2015) and Planets: A Very Short Introduction (Oxford University Press, 2010). He is Educator on the Open University's free learning Badged Open Course (BOC) on Moons and its equivalent FutureLearn Moons MOOC, and chair of the Open University's level 2 course on Planetary Science and the Search for Life.</span></em></p>New research expands the pool of habitable worlds to include super-Earths with hydrogen-rich atmospheres.David Rothery, Professor of Planetary Geosciences, The Open UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1277952019-11-27T18:43:02Z2019-11-27T18:43:02ZA surprisingly big black hole might have swallowed a star from the inside out, and scientists are baffled<figure><img src="https://images.theconversation.com/files/303637/original/file-20191126-84227-1yqzfgm.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C6989%2C4317&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A recently discovered black hole -- found by the way it makes a nearby star wobble -- is hard to square with our understanding of how these dark cosmic objects form.</span> <span class="attribution"><span class="source">NAOC, Chinese Academy of Sciences</span></span></figcaption></figure><p>About 15,000 light years away, in a distant spiral arm of the Milky Way, there is a <a href="https://www.nature.com/articles/s41586-019-1766-2">black hole about 70 times as heavy as the Sun</a>. </p>
<p>This is very surprising for astronomers like me. The black hole seems too big to be the product of a single star collapsing, which poses questions for our theories of how black holes form.</p>
<p>Our team, led by Professor Jifeng Liu at the National Astronomical Observatories, Chinese Academy of Sciences, has dubbed the mysterious object LB-1.</p>
<h2>What’s normal for a black hole?</h2>
<p>Astronomers estimate that our galaxy alone contains about 100 million black holes, created when massive stars have collapsed over the past 13 billion years. </p>
<p>Most of them are inactive and invisible. A relatively small number are sucking in gas from a companion star in orbit around them. This gas releases energy in the form of radiation we can see with telescopes (mostly X-rays), often accompanied by winds and jets. </p>
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Read more:
<a href="https://theconversation.com/like-a-spinning-top-wobbling-jets-from-a-black-hole-thats-feeding-on-a-companion-star-116067">Like a spinning top: wobbling jets from a black hole that's 'feeding' on a companion star</a>
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<p>Until a few years ago, the only way to spot a potential black hole was to look for these X-rays, coming from a bright point-like source. </p>
<p>About two dozen black holes in our galaxy have been identified and measured with this method. They are different sizes, but all between about five and 20 times as heavy as the Sun. </p>
<p>We generally assumed this was the typical mass of all the black hole population in the Milky Way. However, this may be incorrect; active black holes may not be representative of the whole population.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/303608/original/file-20191125-84277-t1njsd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/303608/original/file-20191125-84277-t1njsd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/303608/original/file-20191125-84277-t1njsd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/303608/original/file-20191125-84277-t1njsd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/303608/original/file-20191125-84277-t1njsd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/303608/original/file-20191125-84277-t1njsd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/303608/original/file-20191125-84277-t1njsd.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">
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<span class="caption">The unusual black hole was spotted using the LAMOST telescope at Xinglong Observatory in China.</span>
<span class="attribution"><span class="source">NAOC, Chinese Academy of Sciences</span></span>
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</figure>
<h2>New tools bring an old idea to life</h2>
<p>For our black hole search, we used a different technique. </p>
<p>We surveyed the sky with the Large sky Area Multi-Object fibre Spectroscopic Telescope (LAMOST) in north-east China, looking for bright stars that move around an invisible object. This let us detect the gravitational effect of the black hole, regardless of whether any gas moves from the star to its dark companion.</p>
<p>This technique was proposed by the British astronomer John Michell in 1783, when he first suggested the existence of dark, compact stars orbiting in a binary system with a normal star.</p>
<p>However, it has become practically feasible only with the recent development of large telescopes which let astronomers monitor the motion of thousands of stars at once. </p>
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<a href="https://images.theconversation.com/files/303612/original/file-20191126-84253-33yrpd.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/303612/original/file-20191126-84253-33yrpd.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/303612/original/file-20191126-84253-33yrpd.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=272&fit=crop&dpr=1 600w, https://images.theconversation.com/files/303612/original/file-20191126-84253-33yrpd.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=272&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/303612/original/file-20191126-84253-33yrpd.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=272&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/303612/original/file-20191126-84253-33yrpd.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=342&fit=crop&dpr=1 754w, https://images.theconversation.com/files/303612/original/file-20191126-84253-33yrpd.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=342&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/303612/original/file-20191126-84253-33yrpd.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=342&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">John Michell (1724–1793) was the first scientist to predict the existence of compact stars from which light cannot escape. In 1783 he explained how to find them.</span>
<span class="attribution"><span class="source">Public domain / Philosophical Transactions of the Royal Society of London</span></span>
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<h2>How we spotted LB-1</h2>
<p>LB-1 is the first major result of our search with LAMOST. We saw a star eight times bigger than the Sun, orbiting a dark companion about 70 times as heavy as the Sun. Each orbit took 79 days, and the pair are about one and a half times as far away from each other as Earth and the Sun. </p>
<p>We measured the star’s motion by slight changes in the frequency of the light we detected coming from it, caused by a Doppler shift as the star was moving towards Earth and away from it at different times in its orbit. </p>
<p>We also did the same for a faint glow coming from hydrogen gas around the black hole itself.</p>
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Read more:
<a href="https://theconversation.com/observing-the-invisible-the-long-journey-to-the-first-image-of-a-black-hole-115064">Observing the invisible: the long journey to the first image of a black hole</a>
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<h2>Where did it come from?</h2>
<p>How was LB-1 formed? It is unlikely that it came from the collapse of a single massive star: we think that any big star would lose more mass via stellar winds before it collapsed into a black hole.</p>
<p>One possibility is that two smaller black holes may have formed independently from two stars and then merged (or they may still be orbiting each other). </p>
<p>Another more plausible scenario is that one “ordinary” stellar black hole became engulfed by a massive companion star. The black hole would then swallow most of the host star like a wasp larva inside a caterpillar. </p>
<p>The discovery of LB-1 fits nicely with recent results from the LIGO-Virgo gravitational wave detectors, which catch the ripples in spacetime caused when stellar black holes in distant galaxies collide. </p>
<p>The black holes involved in such collisions are also significantly heavier (up to about 50 solar masses) than the sample of active black holes in the Milky Way. Our direct sighting of LB-1 proves that these overweight stellar black holes also exist in our galaxy.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/303617/original/file-20191126-84231-4f55x5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/303617/original/file-20191126-84231-4f55x5.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/303617/original/file-20191126-84231-4f55x5.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/303617/original/file-20191126-84231-4f55x5.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/303617/original/file-20191126-84231-4f55x5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/303617/original/file-20191126-84231-4f55x5.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/303617/original/file-20191126-84231-4f55x5.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Neutron stars (yellow) are as heavy as 1 to 2 Suns. Black holes discovered from X-ray radiation (purple) have masses between 5 and 20 Suns. Colliding black holes detected from gravitational waves each weigh up to about 50 Suns. LB-1, detected from its orbital motion, has a mass of about 70.</span>
<span class="attribution"><span class="source">LIGO-Virgo / Frank Elavsky / Northwestern / Universita Statale Milano</span>, <span class="license">Author provided</span></span>
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<h2>The black hole family</h2>
<p>Astronomers are still trying to quantify the distribution of black holes across their full range of sizes. </p>
<p>Black holes weighing between 1,000 and 100,000 Suns (so-called intermediate-mass black holes) may reside at the heart of small galaxies or in big star clusters. The space-based Laser Interferometer Space Antenna (<a href="https://www.elisascience.org">LISA</a>) gravitational wave detector (scheduled for launch in 2034) will try to catch their collisions. </p>
<p>Black holes weighing a million to a few billion solar masses are already well known, in the nuclei of larger galaxies and quasars, but their origin is actively debated. We are still a long way away from a complete understanding of how black holes form, grow, and affect their environments, but we are making fast progress.</p><img src="https://counter.theconversation.com/content/127795/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Roberto Soria is an Affiliate researcher at the School of Physics, The University of Sydney. He has previously received funding from the Australian Research Council for black hole studies. </span></em></p>Astronomers using a new technique to hunt black holes found one 70 times as heavy as the SunRoberto Soria, Professor, National Astronomical Observatories, Chinese Academy of SciencesLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1126972019-03-06T19:12:25Z2019-03-06T19:12:25ZWhat pill is that? Cheap and easy pill testing could soon be in your own hands<figure><img src="https://images.theconversation.com/files/262074/original/file-20190305-92280-72n5vs.jpg?ixlib=rb-1.1.0&rect=535%2C294%2C3445%2C2452&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Can you be sure which pill is which? It can be difficult to tell if you've picked the correct medication.</span> <span class="attribution"><span class="source">Shutterstock/perfectla </span></span></figcaption></figure><p>Almost nine out of ten Australians take some form of medication, <a href="http://www.roymorgan.com/findings/7598-health-medications-taken-december-2017-201805201234">according to a recent poll</a>. Much of that will be in tablet form, either prescribed or bought over the counter.</p>
<p>But in the rush of daily life it can be easy to confuse or mix up pills, especially if you or someone you care for is taking several medications. So how can you be sure the pill you’re about to take is the correct one?</p>
<p>We’ve designed some technology that could help with this issue. Also, the tool might one day be suitable for pill testing at music festivals and other events where other pill drugs are available.</p>
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Read more:
<a href="https://theconversation.com/your-period-tracking-app-could-tell-facebook-when-youre-pregnant-an-algorithmic-guardian-could-stop-it-111815">Your period tracking app could tell Facebook when you're pregnant – an 'algorithmic guardian' could stop it</a>
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<p>In our <a href="https://doi.org/10.1145/3214272" title="Assisted Medication Management in Elderly Care Using Miniaturised Near-Infrared Spectroscopy">experiments</a> we have demonstrated how off-the-shelf mobile <a href="http://www.ti.com/tool/DLPNIRNANOEVM">hardware</a> can be used to identify pills. Soon we expect this hardware may be built into most <a href="https://www.forbes.com/sites/paulmonckton/2017/01/11/new-smartphone-can-see-inside-objects/">smartphones</a>.</p>
<h2>How does it work?</h2>
<p>The enabling technology, known as <a href="https://www.nature.com/subjects/near-infrared-spectroscopy">near-infrared spectroscopy</a>, is not new. What is new is that it has been miniaturised.</p>
<p>The technology works by shining infrared light onto the pill. The pill absorbs and reflects some of the light depending on its chemical composition.</p>
<p>By measuring the spectrum of the reflected light, we can obtain a unique signature for this pill. By cross-referencing this signature against a database on known pills or chemicals we can identify the pill.</p>
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<a href="https://images.theconversation.com/files/262083/original/file-20190305-92310-6tmgcx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/262083/original/file-20190305-92310-6tmgcx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/262083/original/file-20190305-92310-6tmgcx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=442&fit=crop&dpr=1 600w, https://images.theconversation.com/files/262083/original/file-20190305-92310-6tmgcx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=442&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/262083/original/file-20190305-92310-6tmgcx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=442&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/262083/original/file-20190305-92310-6tmgcx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=555&fit=crop&dpr=1 754w, https://images.theconversation.com/files/262083/original/file-20190305-92310-6tmgcx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=555&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/262083/original/file-20190305-92310-6tmgcx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=555&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">Our prototype scans pills and displays the results to a paired smartphone.</span>
<span class="attribution"><span class="source">Smart Hospital Living Lab</span>, <span class="license">Author provided</span></span>
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<p>The technology does not damage the pill, since it simply shines infrared light for a couple of seconds.</p>
<p>It does not rely on the visual appearance of the pill at all. In our tests we could accurately differentiate between pills that look virtually identical.</p>
<p>Further accuracy improvements are expected soon. But at this stage we can say this technology allows for pill-testing to be done on the spot, using a mobile device. It’s no longer necessary to ship samples to a dedicated testing facility.</p>
<p>At the moment the technology has been tried on only about 60 pills that can be bought over the counter, such as painkillers, vitamins and other supplements. It could easily be extended to prescription medications.</p>
<p>We actually developed our prototype to be used on prescription and over-the-counter pills, as a way to make sure people are taking the correct medication. This work is being carried out as part of a broader <a href="https://smarthospital.research.unimelb.edu.au/smart-pillbox/">Smart Hospital project</a> to make hospitals safer and more efficient.</p>
<p>For example, medication errors occur when nurses give the incorrect pill to patients in a hospital, or when patients take the wrong pill at home. Our technology has been designed to reduce such errors due to mislabelling or lack of labels.</p>
<p>Which brings us to the <a href="https://www.abc.net.au/news/health/2018-12-21/guide-to-pill-testing-at-australian-music-festivals/10638732">debate on pill testing</a>.</p>
<h2>Checking ‘other’ pills</h2>
<p>It’s become clear that our technology also has the potential to check other types of pills and could be used in scenarios such as people attending music festivals, on-the-spot police checks, or any other situation. </p>
<p>But there are some potential problems here. <a href="http://dx.doi.org/10.1145/3064663.3064738" title="Towards Commoditised Near Infrared Spectroscopy">Our work</a> has shown that environmental factors – such as ambient light – may affect the accuracy of the system, so it’s unlikely to be as accurate as in controlled lab settings.</p>
<p>Also, because our prototype works by cross-referencing to a database of known pills, it can be challenging for the system to identify home-made pills that may not exactly match the chemical composition in our database. </p>
<p>Still, there are a couple of ways to deal with this situation.</p>
<p>First, the system can provide a confidence rating, effectively saying that it has not seen a particular pill before, but it can report which pill it is most similar to. </p>
<p>Second, if we are interested in certain active chemical components in the pill, it can report which of those components are present in the pill, but not necessarily in what amounts.</p>
<h2>The tech’s coming, ready or not</h2>
<p>The technology for pill testing is changing quickly. Soon these changes will have an impact on the arguments used by the <a href="https://www.aph.gov.au/About_Parliament/Parliamentary_Departments/Parliamentary_Library/FlagPost/2018/May/The_pros_and_cons_of_pill_testing">different sides of the pill-testing debate</a> that has gripped Australia. </p>
<p>Our technology demonstrates the potential for making pill-testing a private matter, with no need for any taxpayer-funded testing at events. It is entirely conceivable that soon it will be possible to buy a pill-testing device that you can carry in your pocket and use where and when you choose. </p>
<p>Pill-testing proponents argue that it has the potential in its current form at festivals to be one last safeguard and source of advice before pills are consumed (or not).</p>
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Read more:
<a href="https://theconversation.com/heres-why-doctors-are-backing-pill-testing-at-music-festivals-across-australia-109430">Here's why doctors are backing pill testing at music festivals across Australia</a>
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<p>With the pill-testing technology maturing and being miniaturised even further, we expect within a few years to see widespread prototypes being used. While the hardware is quickly improving, the main challenge remains the analysis that we have developed to differentiate between pills. </p>
<p>We want to raise awareness about this technology and advise all camps in the pill-testing debate that they need to consider how to respond to this technology. </p>
<p>Pill-testing critics might need to consider ways to stop pill-testing given the availability of cheap testing devices – should such devices be banned?</p>
<p>Pill-testing supporters need to consider that pill-testing may soon be possible outside well-staffed festival tents. Therefore, there is a need for new interventions, as well as a consideration of who maintains the pill database: government, industry, NGOs, or perhaps some crowdsourced approach?</p><img src="https://counter.theconversation.com/content/112697/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Vassilis Kostakos receives funding from the Academy of Finland, European Union, Samsung, and the University of Melbourne. </span></em></p>The technology to identify pills is getting cheaper and smaller. That means it could also be used to test the make-up of illegal pills at festivals and other events.Vassilis Kostakos, Professor of Human Computer Interaction, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1096152019-01-22T11:49:45Z2019-01-22T11:49:45ZLessons from ‘Spider-Man’: How video games could change college science education<figure><img src="https://images.theconversation.com/files/253094/original/file-20190109-32127-zrjg01.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The new 'Spider-Man' video game isn't just fun and games – it's also science.</span> <span class="attribution"><a class="source" href="https://insomniac.games/game/spider-man-ps4/">Marvel / Insomniac Games</a></span></figcaption></figure><p>Like many people over the holidays, I spent some time – maybe too much – playing one of the most popular and <a href="https://www.theverge.com/2018/12/17/18137458/best-video-games-2018-xbox-ps4-switch">best reviewed</a> video games of 2018: “<a href="https://insomniac.games/game/spider-man-ps4/">Spider-Man</a>.”</p>
<p>While I thought I’d be taking a break from chemistry research, I found myself web-swinging through virtual research missions all over New York City. I collected samples of <a href="https://www.epa.gov/sites/production/files/2014-03/documents/pahs_factsheet_cdc_2013.pdf">polycyclic aromatic hydrocarbons</a> in Hell’s Kitchen, studied vehicle emissions in Chinatown and determined the chemical composition of atmospheric <a href="https://www.epa.gov/pm-pollution">particulate matter</a> in Midtown.</p>
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<p>“Spider-Man” has many of these eco-friendly research missions. But what I found most encouraging is that the game also includes tools that can potentially teach advanced concepts in chemistry and physics. These tools include adjusting the wavelength and amplitude of radio waves, rewiring circuits to meet target voltages, and what will be examined here, using absorption spectroscopy to identify unknown chemicals.</p>
<p>Beleive it or not, the <a href="https://screenrant.com/spider-man-ps4-9-million-copies-sold/">millions of people</a> playing “Spider-Man” have been unwittingly introduced to principles of quantum mechanics. There is a lot of veiled science to this aspect of the video game. Perhaps more importantly – as a <a href="https://www.researchgate.net/profile/Aaron_Harrison3">chemistry researcher</a> and university lecturer – I believe the game represents an interesting opportunity to teach science in a fun and engaging way in higher education.</p>
<h2>Spectroscopy and ‘Spider-Man’</h2>
<p>To better understand the scientific technique that players simulate in “Spider-Man,” it helps to have a short primer on what absorption spectroscopy is.</p>
<p>The interaction of light with matter is the most powerful means scientists have to understand what matter is made of. When matter does not interact with light, we are quite literally left in the dark. This problem is made obvious in the still unknown composition of <a href="https://home.cern/science/physics/dark-matter">dark matter</a> that constitutes the vast majority of matter in the universe.</p>
<p>Using light to study ordinary matter like atoms and molecules is a broad field of science known as <a href="http://astronomy.swin.edu.au/cosmos/S/Spectroscopy">spectroscopy</a>. It is an important part of university courses in chemistry and physics. There are currently many different types of spectroscopy. However, the underlying concepts are almost entirely the same as the original version that began in the 17th century when Isaac Newton first dispersed sunlight with a prism.</p>
<p>As famously illustrated on Pink Floyd’s “Dark Side of the Moon” album <a href="https://medium.com/@davidjdeal/pink-floyds-the-dark-side-of-the-moon-how-an-album-cover-became-an-icon-e95bae0bdc32">cover</a>, dispersing the white light of the sun with a prism reveals its continuous color spectrum extending from violet (higher energy, shorter wavelength) to red (lower energy, longer wavelength). However, if this is done carefully, you would find that this continuous spectrum is patterned with <a href="https://chem.libretexts.org/Courses/University_of_Missouri/MU%3A__1330H_(Keller)/06._Electronic_Structure_of_Atoms/6.3%3A_Line_Spectra_and_the_Bohr_Model">intermittent dark bands</a>. </p>
<p>While the origin of these dark bands was not fully understood until the 20th century, scientists now know that they are due to absorption of specific wavelengths of light by atoms and molecules present in the sun. In fact, this kind of spectroscopy led to the discovery of helium in the solar spectrum before it was identified on Earth. This is why it derives its name from the Greek “helios” meaning sun.</p>
<p>So what causes this phenomenon? Atoms and molecules have a set of energy levels that depend on how their electrons are arranged. The absorption of light – which remember is energy – can cause the electrons to rearrange into these different levels. The catch is that the energy – or wavelength – of light must exactly match the energy difference between two electron arrangements in an atom or molecule for absorption to occur. This set of energies is unique for each chemical and leads to a distinct absorption spectrum much like a fingerprint from which it can be identified.</p>
<p>In “Spider-Man,” the player identifies unknown substances using simplified versions of these spectra.</p>
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<img alt="" src="https://images.theconversation.com/files/254402/original/file-20190117-32810-1kgjfrj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/254402/original/file-20190117-32810-1kgjfrj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/254402/original/file-20190117-32810-1kgjfrj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/254402/original/file-20190117-32810-1kgjfrj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/254402/original/file-20190117-32810-1kgjfrj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/254402/original/file-20190117-32810-1kgjfrj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/254402/original/file-20190117-32810-1kgjfrj.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">
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<span class="caption">Spectrum of Unknown Molecule from Research Mission.</span>
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<p>The goal is to match the pattern in the spectrum using the fragment inventory provided to give the absorption spectrum of the unknown substance. Unfortunately for chemists everywhere, determining the chemical structure of an unknown molecule is much more complicated.</p>
<p>Still, there is a significant amount of science conveyed in the video game version of what a spectroscopist would call assigning this spectrum. Only slight modifications and additional explanation could make these parts of the game an excellent way to teach these concepts to undergraduate science students. But are video games ever used in higher education?</p>
<h2>Video games in higher education</h2>
<p><a href="https://oedb.org/ilibrarian/50-educational-video-games-that-homeschoolers-love/">Video games for teaching</a> more elementary skills like arithmetic or spelling are common. Similarly, colleges and universities are <a href="https://www.ajpe.org/doi/abs/10.5688/ajpe79447">increasingly infusing video games</a> into their coursework.</p>
<p>In a recent publication in the journal Nature Chemistry, researchers presented a modified version of the video game “Minecraft” called “<a href="https://www.polycraftworld.com/">PolyCraft World</a>.” In this game, the player learns polymer chemistry by crafting materials in the game. Preliminary results showed that students <a href="https://www.nature.com/articles/nchem.2694">learned real chemistry</a> through the game even though they weren’t doing it for grades or getting regular classroom instruction.</p>
<p>In the popular game “<a href="https://www.kerbalspaceprogram.com">Kerbal Space Program</a>,” the player builds their own space program by successfully launching rockets into orbit. The game was not originally intended for educational purposes but implements rigorous orbital mechanics in its physics calculations. It is so accurate that NASA <a href="https://spinoff.nasa.gov/Spinoff2015/partnership_1.html">joined the game’s developers</a> to create new missions, and it now has a <a href="https://kerbaledu.com/">teaching-ready standalone game</a> that could be used directly in university physics courses.</p>
<p>A unique approach has been taken with the biochemistry-based game “<a href="https://fold.it/portal/">FoldIt</a>.” This game serves as both an educational as well as a <a href="https://theconversation.com/expanding-citizen-science-models-to-enhance-open-innovation-61554">citizen science platform</a>. In the game, players manipulate the structures of real proteins to search for the “best” or lowest energy structures. Results published in the journal Nature showed that the <a href="https://www.nature.com/articles/nature09304">player’s search methods</a> can be successfully combined with computer-based algorithms to <a href="https://www.nbcnews.com/sciencemain/gamers-solve-molecular-puzzle-baffled-scientists-6C10402813">solve actual scientific problems</a>.</p>
<p>The use of video games in higher education is a real possibility and could even have a promising future in higher education given the advantages of delivering educational content through a video game format. These advantages include things such as remote access, personalized student progress and immediate feedback. However, creating an engaging video game from scratch is challenging, costly and time-consuming. As <a href="https://www.nature.com/articles/nchem.2694">indicated</a> by the creators of “PolyCraft World,” finding existing games to modify for educational purposes – like the research missions in “Spider-Man” – could be the best way forward.</p><img src="https://counter.theconversation.com/content/109615/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Aaron W. Harrison does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The latest version of the Spider-Man video game offers insights into how science could be taught more effectively to today’s college students, a researcher and video game enthusiast suggests.Aaron W. Harrison, Teaching and Research Fellow, Chapman UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/984072018-06-28T14:04:10Z2018-06-28T14:04:10ZHow the discovery of a protein’s secret function could boost solar tech<figure><img src="https://images.theconversation.com/files/225293/original/file-20180628-112628-1exrw1o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Understanding how certain proteins deal with light absorption can inspire modern solar technology.</span> <span class="attribution"><span class="source">symbiot/Shutterstock</span></span></figcaption></figure><p>Proteins are “large”, complex molecules that perform most of the complicated and vital tasks in living organisms. So when scientists study proteins, they can produce blueprints for a new generation of bio-inspired technologies. </p>
<p>But proteins guard their secrets very closely. Luckily, there are ways of making them “sing” – and making really interesting discoveries from the resulting sounds.</p>
<p>Together with our collaborators in Bangladesh and the Netherlands, we <a href="https://pubs.acs.org/doi/abs/10.1021/acs.jpclett.8b00621">recently uncovered</a> that a well known protein involved in photosynthesis can sometimes behave like two different proteins – or put differently, it can, as it were, sing two different songs.</p>
<p>The protein is known as <a href="https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/phycocyanin">Phycocyanin</a> and is responsible for the collection of solar energy in <a href="http://www.ucmp.berkeley.edu/bacteria/cyanointro.html">cyanobacteria</a>. These microorganisms perform photosynthesis, just like plants, and are important for oxygen production. Our findings show that Phycocyanin can switch between two different functions. </p>
<p>This ability, if harnessed properly, could help develop new smart solar technologies. Current solar panels aren’t very efficient because they’re not very responsive to changing light conditions. They were designed to work under the full sun, preferably during a cloudless day.</p>
<p>One of the challenges of solar cell technologies is that the amount and quality of sunlight reaching the Earth changes all the time. These changes can be caused by clouds or trees swaying in the wind. Understanding how Phycocyanin can switch between different functions can teach us how to design a solar panel that will adapt to different conditions.</p>
<h2>Using light to hear a protein’s “song”</h2>
<p>We used an experimental tool called <a href="https://www.britannica.com/science/spectroscopy">light spectroscopy</a> to make our finding. The technique works by shining laser light on specific proteins and observing how the light patterns change when the protein adopts a slightly different structure. It’s a sensitive technique that can give a lot of detailed information and is used in a vast range of applications, from medical diagnostics to geology.</p>
<p>The outcomes of the interaction between the light and the proteins also depend on the state and properties of the proteins. We turned to a very special spectroscopic method known as single molecule spectroscopy, which allowed us to observe the properties of individual proteins. </p>
<p>To understand the advantage of this approach, think of a room filled with people. Ask them all to start singing their favourite songs – loudly. The result is likely to be a cacophony. In a similar way, trying to extract information from billions of proteins all at once generates a lot of noise.</p>
<p>But a different approach can produce a different outcome: leave only one person in the room and ask them to sing. After a while, ask another person, and then another. This time you should be able to clearly hear different songs and distinguish the words as well as the different tones and timbres. Similarly, single molecule spectroscopy gives one access to all the “songs, words, tones and timbre” of individual proteins.</p>
<p>That’s how we pinpointed that Phycocyanin can sing two “songs”. Its primary function is to collect the sun’s energy and then pass it on to its neighbours (proteins of a similar type) with amazing efficiency. </p>
<p>But, as emerged from our experiments, sometimes Phycocyanin enters a different state. When this happens, Phycocyanin isn’t able to pass the sunlight energy to its known partners as it usually does. In fact, it most likely sends the absorbed energy directly to the photosynthetic reaction centre, where the energy is converted into stable chemical energy. This shows that biological molecules have the ability to change their behaviour depending on the immediate needs.</p>
<h2>Applications</h2>
<p>This ability holds exciting possibilities for solar devices. Scientists could design an artificial system that can “sing many songs” and dynamically switch between them in a smart way. </p>
<p>These devices could then convert solar energy with a greater efficiency, which has many benefits. For example, bio-inspired, smart and flexible solar panels would not require perfect sunny weather and regular cleaning to achieve the highest efficiency.</p><img src="https://counter.theconversation.com/content/98407/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michal Gwizdala receives funding from The University of Pretoria and previously received funding from EU via Marie Sklodowska Curie Actions ITN Harvest, European Molecular Biology Organisation via Long-Term Fellowship, VU Amsterdam and Claude Leon Foundation via Post-doctoral Fellowship.</span></em></p><p class="fine-print"><em><span>Tjaart Krüger receives funding from the University of Pretoria, the Department of Science and Technology and the National Research Foundation.</span></em></p>Proteins guard their secrets closely, but once you get them to “sing”, there’s an enormous amount to learn.Michal Gwizdala, Postdoctoral researcher in photosynthesis, Vrije Universiteit AmsterdamTjaart Krüger, Associate Professor in Biophysics, University of PretoriaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/965062018-05-18T09:18:19Z2018-05-18T09:18:19ZWhen did the lights first come on in the universe? A galaxy close to the dawn of time gives a clue<figure><img src="https://images.theconversation.com/files/219421/original/file-20180517-26300-88ah5v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Galaxy cluster MACS J1149.5+2223 taken with the Hubble Space Telescope. The inset image is the very distant galaxy MACS1149-JD1</span> <span class="attribution"><span class="source">ALMA (ESO/NAOJ/NRAO), NASA/ESA Hubble Space Telescope, W. Zheng (JHU), M. Postman (STScI), the CLASH Team, Hashimoto et al.</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>It is springtime in the Northern hemisphere. Countless buds that have been waiting patiently on the stems and branches of trees and shrubs are now blossoming into life. The cosmic equivalent of this season is the time between a few hundred million and a billion years after the Big Bang. This is when the first stars and galaxies ignited, spewing light into the dark universe. </p>
<p>It is a time in the history of the universe that we are desperate to chart, because it represents part of the cosmological story that we have yet to understand. Now astronomers have detected oxygen in a galaxy further away than ever before – and it existed just 500m years after the Big Bang. The results, <a href="http://nature.com/articles/doi:10.1038/s41586-018-0117-z">published in Nature</a>, are hugely important as they provide new insights into when the first stars formed. </p>
<p>The period of this “cosmic dawn” is important not only because this is when the first galaxies were born, but a crucial cosmic transition also took place. In this process, atoms in the electrically neutral intergalactic medium – a wide sea of hydrogen gas surrounding galaxies – were bombarded with ultraviolet radiation escaping from the first galaxies. This stripped away electrons from atoms and made the gas charged, or “ionised”.</p>
<p>The event, called the <a href="https://theconversation.com/after-our-universes-cosmic-dawn-what-happened-to-all-its-original-hydrogen-65527">Epoch of Reionisation</a>, is still mysterious. We’d like to know – or better yet, <em>see</em> – when this process started. Part of that quest involves finding the most distant galaxies.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/219236/original/file-20180516-155619-14remy0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/219236/original/file-20180516-155619-14remy0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=250&fit=crop&dpr=1 600w, https://images.theconversation.com/files/219236/original/file-20180516-155619-14remy0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=250&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/219236/original/file-20180516-155619-14remy0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=250&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/219236/original/file-20180516-155619-14remy0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=314&fit=crop&dpr=1 754w, https://images.theconversation.com/files/219236/original/file-20180516-155619-14remy0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=314&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/219236/original/file-20180516-155619-14remy0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=314&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 Epoch of Reionisation.</span>
<span class="attribution"><span class="source">ESA C. Carreau</span></span>
</figcaption>
</figure>
<p>When we look out into the universe we detect light that has taken some appreciable time to traverse the gulf that separates us from other stars and galaxies. The light from the screen you are reading this on has taken about a third of a nanosecond to reach your eyes. Light from the nearest star beyond our sun takes four years to reach us. Amazingly, light from the galaxy at the centre of the new study, called MACS1149-JD1, has taken 13 <em>billion</em> years to be detected here on Earth. That means we see MACS1149-JD1 as it was 13 billion years in the past, around 500m years after the Big Bang.</p>
<h2>Powerful gaze</h2>
<p>Using a telescope called the <a href="http://www.almaobservatory.org/en/home/">Atacama Large Millimetre/sub-millimetre Array (ALMA)</a>, the scientists detected a strong signal (an emission line) within the distant galaxy. Just as a prism disperses the light of the sun into a rainbow spectrum, we can disperse the light of distant galaxies, too. This is called spectroscopy. Emission lines are bright spikes in the spectra of galaxies that originate from different elements that can each release light of a very specific energy. </p>
<p>This particular emission line came from ionised oxygen gas. Its presence tells us that the galaxy was forming stars at the time, because the energy required to ionise it must have come from massive, hot, young stars.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/219177/original/file-20180516-155623-19v0gc7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/219177/original/file-20180516-155623-19v0gc7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=221&fit=crop&dpr=1 600w, https://images.theconversation.com/files/219177/original/file-20180516-155623-19v0gc7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=221&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/219177/original/file-20180516-155623-19v0gc7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=221&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/219177/original/file-20180516-155623-19v0gc7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=278&fit=crop&dpr=1 754w, https://images.theconversation.com/files/219177/original/file-20180516-155623-19v0gc7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=278&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/219177/original/file-20180516-155623-19v0gc7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=278&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The ALMA Observatory.</span>
<span class="attribution"><span class="source">Carlos Padilla – AUI/NRAO</span></span>
</figcaption>
</figure>
<p>If we measured the same type of gas here on Earth, we would detect it at a wavelength of 0.088 millimetres. But other galaxies are receding away from us due to cosmic expansion, and this causes the light they emit to increase in wavelength during the time it takes for the photons to reach us. The more distant a galaxy is, the larger the increase in wavelength. </p>
<p>This is called <a href="http://astronomy.swin.edu.au/cosmos/C/cosmological+redshift">redshift</a>, and it ultimately tells us the ratio between the size of the universe when the light was first emitted and the size of the universe today. The oxygen emission line observed in MACS1149-JD1 is actually detected at 0.88 millimetres – its wavelength has been stretched by a factor of 10. This means that at the time the light was emitted, the universe was a factor of 10 times smaller than it is today, and just four per cent of its present age. </p>
<p>In this way, the ability to detect emission lines in distant galaxies allows us to pinpoint at what stage in cosmic history we are seeing them. But of course, the most distant galaxies are also the faintest – you need ever more powerful telescopes if you want to peer back further. </p>
<p>ALMA (consisting of 66 individual telescopes working together) is an incredibly powerful telescope – it is revolutionising our view of the early universe. Not only is it providing exquisite sensitivity, but operates in part of the electromagnetic spectrum that gives access to a wide range of emission lines.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/219367/original/file-20180517-155607-369ubf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/219367/original/file-20180517-155607-369ubf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/219367/original/file-20180517-155607-369ubf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/219367/original/file-20180517-155607-369ubf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/219367/original/file-20180517-155607-369ubf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/219367/original/file-20180517-155607-369ubf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/219367/original/file-20180517-155607-369ubf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Gravitational lensing.</span>
<span class="attribution"><span class="source">NASA, ESA & L. Calcada</span></span>
</figcaption>
</figure>
<p>To help matters, the team also exploited a natural telescope: a <a href="https://theconversation.com/method-to-weigh-galaxy-clusters-could-help-us-understand-mysterious-dark-matter-structures-85023">massive cluster of galaxies</a>. Light from MACS1149-JD1 has had to pass through this intervening cluster on its journey to ALMA. This is so massive that it significantly warps spacetime, meaning that the light is “bent” in a process called <a href="https://theconversation.com/how-we-managed-what-einstein-thought-was-impossible-and-used-his-theory-to-weigh-a-star-79050">gravitational lensing</a>. Gravitational lensing amplifies the brightness of MACS1149-JD1, making it a little easier to see.</p>
<h2>Indirect glimpse of first stars</h2>
<p>MACS1149-JD1 is not the <a href="https://en.wikipedia.org/wiki/GN-z11">most distant galaxy on record</a>, but what this new study adds to our understanding is an insight into the history of the formation of the galaxy. This happened hundreds of millions of years before the current observation, and much further back than even the most distant galaxy known. </p>
<p>In fact, the presence of oxygen in the galaxy tells us that star formation must have been going on for some time in MACS1149-JD1. That’s because oxygen can only be formed within stars in a process called stellar nucleosynthesis. But what we don’t know is when those stars first ignited.</p>
<p>By combining data from the <a href="https://www.nasa.gov/mission_pages/hubble/story/index.html">Hubble Space Telescope</a>, the <a href="http://www.eso.org/public/unitedkingdom/teles-instr/paranal-observatory/vlt/">European Southern Observatory’s Very Large Telescope</a> and the <a href="http://www.spitzer.caltech.edu/">Spitzer Space Telescope</a>, the authors made a model of the “stellar population” within MACS1149-JD1. This allowed them to estimate the mixture of stars that give rise to the emission from the galaxy observed in certain bands of the <a href="https://imagine.gsfc.nasa.gov/science/toolbox/emspectrum1.html">electromagnetic spectrum</a>.</p>
<p>The model involves estimating the “star formation history” of the galaxy, describing the rate of production of stars in the past. The modelling suggests that, in order to produce the observed emission, stars must have started forming just 250m years after the Big Bang, when the universe was just two per cent of its present age. In other words, MACS1149-JD1 was already a fairly well established galaxy, even at this early time. </p>
<p>This is a huge scientific accomplishment as it is currently impossible to observe galaxies that existed 250m years after the Big Bang. However, the new <a href="https://www.jwst.nasa.gov/">James Webb Space Telescope</a>, which is due for launch in 2020, may be able to do so. </p>
<p>But until then, thanks to the new study, we now have a way of indirectly studying when stars first formed in ancient galaxies like MACS1149-JD1. In effect, by observing the blossom, astronomers have estimated when the bud first opened.</p><img src="https://counter.theconversation.com/content/96506/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>James Geach receives funding from The Royal Society.</span></em></p>Astronomers have indirectly spotted some of the first stars in the universe by making their most distant detection of oxygen in a galaxy that existed just 500m years after the Big Bang.James Geach, Royal Society University Research Fellow, University of HertfordshireLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/953792018-04-23T20:08:43Z2018-04-23T20:08:43ZFrom pancakes to soccer balls, new study shows how galaxies change shape as they age<figure><img src="https://images.theconversation.com/files/215804/original/file-20180422-75093-1jvpzys.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Sombrero galaxy reveals the extremes of age and shape.
</span> <span class="attribution"><a class="source" href="https://www.nasa.gov/multimedia/imagegallery/image_feature_283.html">NASA/ESA and The Hubble Heritage Team (STScI/AURA)</a></span></figcaption></figure><p>Galaxies are a fundamental part of the 13.7 billion-year-old universe. Understanding how a system as complex and striking as our own Milky Way galaxy formed after the Big Bang is one of the great themes of modern astronomy.</p>
<p>Our research, <a href="http://nature.com/articles/doi:10.1038/s41550-018-0436-x">published today in Nature Astronomy</a>, has identified a surprising connection between the age of a galaxy and its three-dimensional shape.</p>
<p>As galaxies get older they get rounder, and fall victim to the middle-aged spread that catches many of us humans here on Earth.</p>
<p>We’ve known for a long time that shape and age are linked in very extreme galaxies – that is, very flat ones and very round ones. But this is the first time we have shown this is true for all kinds of galaxies – all shapes, all ages, all masses. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/live-fast-die-young-a-massive-dead-red-galaxy-seen-for-the-first-time-in-the-early-universe-75774">Live fast, die young: a massive 'dead red' galaxy seen for the first time in the early Universe</a>
</strong>
</em>
</p>
<hr>
<h2>Unveiling the true face of a galaxy</h2>
<p>In this study we calculated both the age and shape of galaxies using different techniques.</p>
<p>Assigning an age to a galaxy is tricky. They don’t have a single birth date for when they suddenly popped into existence. </p>
<p>We assessed the average age of the stars in a galaxy as a measure of the galaxy’s age. Young galaxies have a large fraction of recently formed hot blue stars, whereas old galaxies mostly contain colder red stars formed shortly after the Big Bang.</p>
<p>Spectroscopy — splitting the light from a galaxy into many different colours — allows us to measure the <a href="https://newsroom.unsw.edu.au/news/science-tech/finding-our-sun%E2%80%99s-lost-siblings">average age of stars in a galaxy</a>. This technique gives a much higher precision than simply using blue or red images as is typically done.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/185410/original/file-20170911-9414-nc2zxk.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/185410/original/file-20170911-9414-nc2zxk.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/185410/original/file-20170911-9414-nc2zxk.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=363&fit=crop&dpr=1 600w, https://images.theconversation.com/files/185410/original/file-20170911-9414-nc2zxk.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=363&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/185410/original/file-20170911-9414-nc2zxk.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=363&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/185410/original/file-20170911-9414-nc2zxk.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=456&fit=crop&dpr=1 754w, https://images.theconversation.com/files/185410/original/file-20170911-9414-nc2zxk.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=456&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/185410/original/file-20170911-9414-nc2zxk.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=456&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 selection of SAMI galaxies imaged with the Hyper Suprime Cam on the Subaru Telescope in Hawaii.</span>
<span class="attribution"><span class="source">National Astronomical Observatory of Japan (NAOJ), Caroline Foster (The University of Sydney) and Dan Taranu (University of Western Australia)</span></span>
</figcaption>
</figure>
<p>To measure a galaxy’s <a href="https://theconversation.com/3d-view-helps-us-to-understand-how-galaxies-formed-and-evolved-81318">true three-dimensional shape</a> and ellipticity, you have to measure how its stars move around. </p>
<p>Ellipticity is simply a measure of how squashed a galaxy is with respect to a perfect sphere. An ellipticity of zero means a galaxy is a perfect sphere like a soccer ball. But as the measured ellipticity increases from zero towards one, the galaxy becomes more and more squashed – from a roundish pumpkin shape to a thin disk like a pancake.</p>
<p>We see galaxies as two-dimensional images projected onto the sky, but that doesn’t tell us what they really look like in three dimensions. If we can also measure how the stars in a galaxy are moving we can infer their true, three-dimensional shape. </p>
<p>Spectroscopy lets us do this via the <a href="https://theconversation.com/explainer-the-doppler-effect-7475">Doppler effect</a>. We can measure shifts in the wavelength of light emitted by stars, which depend on whether those stars are moving towards us or away from us, and so measure their motions. </p>
<p>We did this using <a href="https://sami-survey.org/">SAMI</a>, the Sydney-Australian-Astronomical-Observatory Multi-object Integral-Field Spectrograph, on the 3.9-metre <a href="https://www.aao.gov.au/about-us/AAT">Anglo-Australian Telescope</a> at Siding Spring Observatory. The SAMI instrument provides 13 optical fibre units that can “dissect” galaxies using spectroscopy, providing unique 3D data. </p>
<p>Over the past couple of years, the SAMI Galaxy Survey team has gathered 3D measurements for more than a <a href="https://www.aao.gov.au/news-media/media-releases/scientists-unveil-new-3D-view-of-galaxies">thousand galaxies</a> of all kinds, and with a hundred-fold range in mass.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/j4yxBwmLxms?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">This astronomical time-lapse video features the unique SAMI instrument at the 3.9m Anglo-Australian Telescope and the beauty of the dark sky over Siding Spring Observatory. Credit: Ángel R. López-Sánchez (Australian Astronomical Observatory / Macquarie University)</span></figcaption>
</figure>
<h2>Changing the shape of galaxies</h2>
<p>So what do we learn about the processes that shape galaxies from this result? </p>
<p>Galaxies tend to form their stars in a pancake-like disk with high ellipticity. But these stars don’t stay in that thin disk as the galaxy ages. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/215812/original/file-20180422-75110-1ll3bmo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/215812/original/file-20180422-75110-1ll3bmo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/215812/original/file-20180422-75110-1ll3bmo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=564&fit=crop&dpr=1 600w, https://images.theconversation.com/files/215812/original/file-20180422-75110-1ll3bmo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=564&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/215812/original/file-20180422-75110-1ll3bmo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=564&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/215812/original/file-20180422-75110-1ll3bmo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=709&fit=crop&dpr=1 754w, https://images.theconversation.com/files/215812/original/file-20180422-75110-1ll3bmo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=709&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/215812/original/file-20180422-75110-1ll3bmo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=709&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 edge-on view of spiral galaxy NGC 3501, a young galaxy with an extremely thin disk.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/mission_pages/hubble/science/milky-way-collide.html">ESA/Hubble & NASA</a></span>
</figcaption>
</figure>
<p>There are lots of different gentle events, known as <a href="http://astronomy.swin.edu.au/cosmos/S/Secular+Evolution">secular processes</a>, that cause the disk to puff up, becoming rounder and less squashed. A galaxy can be bombarded by other, smaller galaxies. Even if a galaxy is isolated, internal dynamical processes can cause the disk to thicken.</p>
<p>The net result is, as a galaxy ages, its initial thin disk of stars starts to thicken – the middle-aged spread – and the galaxy becomes older, rounder and less squashed.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/215880/original/file-20180423-75093-u9nvcf.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/215880/original/file-20180423-75093-u9nvcf.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/215880/original/file-20180423-75093-u9nvcf.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/215880/original/file-20180423-75093-u9nvcf.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/215880/original/file-20180423-75093-u9nvcf.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/215880/original/file-20180423-75093-u9nvcf.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/215880/original/file-20180423-75093-u9nvcf.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/215880/original/file-20180423-75093-u9nvcf.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Elliptical galaxy NGC 4660 is a much older and puffier galaxy than spiral galaxy NGC 3501.</span>
<span class="attribution"><a class="source" href="https://www.spacetelescope.org/images/heic0815b/">SA, NASA and E. Peng (Peking University, Beijing)</a></span>
</figcaption>
</figure>
<p>In some cases a galaxy can experience more extreme events that radically change its shape. <a href="https://www.space.com/22395-elliptical-galaxies.html">Elliptical galaxies</a>, <a href="https://www.nasa.gov/feature/goddard/2017/messier-87">such as M87</a>, are the oldest and roundest galaxies in the universe. </p>
<p>Astronomers think these galaxies are formed in major mergers — dramatic collisions between galaxies that result in one massive galaxy being entirely consumed by another. </p>
<p>Because these events are so significant, they scatter all the stars out of the disk of a galaxy, resulting in a much rounder shape. They also prevent any new stars being formed after the merger, causing the galaxy to age rapidly. The end result is an old, very round galaxy.</p>
<figure>
<iframe src="https://player.vimeo.com/video/43238292" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
<figcaption><span class="caption">The inevitable fate of our Milky Way: the collision between our galaxy and Andromeda. Credit: NASA / ESA / STScI / Columbia University / F. Summers / G. Besla / R. van der Marel.</span></figcaption>
</figure>
<h2>Closer to home</h2>
<p>If we look at our own Milky Way galaxy, which is more than 10 billion years old, we can see examples of this story. </p>
<p>The youngest part of the Milky Way, where stars are still being formed, is the thin disk, which has a very squashed, pancake-like shape. The Milky Way also contains rounder and older components, a thick disk and a bulge, but their origin is still mostly unknown.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/when-galaxies-collide-size-matters-if-you-want-to-know-the-fate-of-our-milky-way-91826">When galaxies collide, size matters if you want to know the fate of our Milky Way</a>
</strong>
</em>
</p>
<hr>
<p>We know that eventually the Milky Way will merge with our galactic neighbour, the Andromeda galaxy. <a href="http://adsabs.harvard.edu/abs/2012ApJ...753....9V">Predictions are</a> that this will result in a very round, very old giant elliptical galaxy. </p>
<p>So, by studying the processes that shape other nearby galaxies, we can learn a lot about the past, and the fate of our own.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/215860/original/file-20180423-75114-19vaw15.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/215860/original/file-20180423-75114-19vaw15.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/215860/original/file-20180423-75114-19vaw15.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/215860/original/file-20180423-75114-19vaw15.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/215860/original/file-20180423-75114-19vaw15.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/215860/original/file-20180423-75114-19vaw15.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/215860/original/file-20180423-75114-19vaw15.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">This illustration shows a stage in the predicted merger between our Milky Way galaxy and the neighbouring Andromeda galaxy.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/mission_pages/hubble/science/milky-way-collide.html">NASA; ESA; Z. Levay and R. van der Marel, STScI; T. Hallas; and A. Mellinger</a></span>
</figcaption>
</figure><img src="https://counter.theconversation.com/content/95379/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jesse van de Sande works for the University of Sydney and receives funding from the Australian Research Council (FL140100278). The Sydney-AAO Multi-object Integral field spectrograph (SAMI) was developed jointly by the University of Sydney and the Australian Astronomical Observatory. The SAMI Galaxy Survey is funded by the Australian Research Council Centre of Excellence for All-sky Astrophysics (CAASTRO), through project number CE110001020, and other participating institutions. Parts of this research were conducted by the Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), through project number CE170100013.
</span></em></p><p class="fine-print"><em><span>Nicholas Scott works for the University of Sydney and is funded by a University of Sydney Postdoctoral Research Fellowship.</span></em></p>As galaxies get older they get rounder, and fall victim to the middle-aged spread that catches many of us humans here on Earth.Jesse van de Sande, Postdoctoral Research Associate in Astronomy, University of SydneyNicholas Scott, Postdoctoral Research Fellow in Astronomy, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/891162018-02-13T11:45:07Z2018-02-13T11:45:07ZPrehistoric wine discovered in inaccessible caves forces a rethink of ancient Sicilian culture<figure><img src="https://images.theconversation.com/files/206085/original/file-20180212-58318-1dt1mer.jpg?ixlib=rb-1.1.0&rect=0%2C58%2C5304%2C3673&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Deep inside Monte Kronio, hot, humid and sulfurous caves held an ancient secret.</span> <span class="attribution"><span class="source">Giuseppe Savino, La Venta Esplorazioni Geografiche</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Monte Kronio rises 1,300 feet above the geothermally active landscape of southwestern Sicily. Hidden in its bowels is a labyrinthine system of caves, filled with hot sulfuric vapors. At lower levels, these caves average 99 degrees Fahrenheit and 100 percent humidity. Human sweat cannot evaporate and heat stroke can result in less than 20 minutes of exposure to these underground conditions.</p>
<p>Nonetheless, people have been visiting the caves of Monte Kronio since as far back as 8,000 years ago. They’ve left behind vessels from the Copper Age (early sixth to early third millennium B.C.) as well as various sizes of ceramic storage jars, jugs and basins. In the deepest cavities of the mountain these artifacts sometimes lie with human skeletons.</p>
<p>Archaeologists debate what unknown religious practices these artifacts might be evidence of. Did worshipers sacrifice their lives bringing offerings to placate a mysterious deity who puffed gasses inside Monte Kronio? Or did these people bury high-ranking individuals in that special place, close to what was probably considered a source of magical power?</p>
<p>One of the most puzzling of questions around this prehistoric site has been what those vessels contained. What substance was so precious it might mollify a deity or properly accompany dead chiefs and warriors on their trip to the underworld?</p>
<p>Using tiny samples, scraped from these ancient artifacts, my analysis came up with a surprising answer: wine. And that discovery has big implications for the story archaeologists tell about the people who lived in this time and place.</p>
<h2>Analyzing scraping samples</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/204944/original/file-20180205-14078-1rjx3n4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/204944/original/file-20180205-14078-1rjx3n4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/204944/original/file-20180205-14078-1rjx3n4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=785&fit=crop&dpr=1 600w, https://images.theconversation.com/files/204944/original/file-20180205-14078-1rjx3n4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=785&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/204944/original/file-20180205-14078-1rjx3n4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=785&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/204944/original/file-20180205-14078-1rjx3n4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=986&fit=crop&dpr=1 754w, https://images.theconversation.com/files/204944/original/file-20180205-14078-1rjx3n4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=986&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/204944/original/file-20180205-14078-1rjx3n4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=986&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The storage jars and their mysterious contents, left millennia ago in the recesses of Monte Kronio.</span>
<span class="attribution"><span class="source">Davide Tanasi et al. 2017</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>In November 2012, a team of <a href="http://www.laventa.it">expert geographers</a> <a href="http://www.boegan.it">and speleologists</a> ventured once again into the <a href="http://hdl.handle.net/2318/1524671">dangerous underground complex of Monte Kronio</a>. They escorted archaeologists from the Superintendence of Agrigento down more than 300 feet to document artifacts and to take samples. The scientists scraped the inner walls of five ceramic vessels, removing about 100 mg (0.0035 ounces) of powder from each.</p>
<p>I led an international team of scholars, which hoped analyzing this dark brown residue could shed some light on what these Copper Age containers from Monte Kronio originally carried. Our plan was to use cutting-edge chemical techniques to characterize the organic residue.</p>
<p>We decided to use three different approaches. <a href="https://www.chemguide.co.uk/analysis/nmr/background.html">Nuclear magnetic resonance spectroscopy</a> (NMR) would be able to tell us the physical and chemical properties of the atoms and molecules present. We turned to <a href="http://blog.phenom-world.com/edx-analysis-scanning-electron-micrscope-sem">scanning electron microscopy with energy dispersive X-ray spectroscopy</a> (SEM/EDX) and the <a href="https://www.azom.com/article.aspx?ArticleID=5958">attenuated total reflectance Fourier transform infrared spectroscopy</a> (ATR FT-IR) for the elemental analysis – the chemical characterization of the samples.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/205775/original/file-20180209-51706-15x15km.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/205775/original/file-20180209-51706-15x15km.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/205775/original/file-20180209-51706-15x15km.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=765&fit=crop&dpr=1 600w, https://images.theconversation.com/files/205775/original/file-20180209-51706-15x15km.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=765&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/205775/original/file-20180209-51706-15x15km.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=765&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/205775/original/file-20180209-51706-15x15km.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=962&fit=crop&dpr=1 754w, https://images.theconversation.com/files/205775/original/file-20180209-51706-15x15km.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=962&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/205775/original/file-20180209-51706-15x15km.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=962&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 were no second chances with the tiny amount of samples that had been scraped from the ancient vessels.</span>
<span class="attribution"><span class="source">Davide Tanasi</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>These analysis methods are destructive: The sample gets used up when we run the tests. Since we had just that precious 100 mg of powder from each vessel, we needed to be extremely careful as we prepared the samples. If we messed up the analysis, we couldn’t just run it all over again.</p>
<p>We found that four of the five Copper Age large storage jars <a href="https://doi.org/10.1016/j.microc.2017.08.010">contained an organic residue</a>. Two contained animal fats and another held plant residues, thanks to what we inferred was a semi-liquid kind of stew partially absorbed by the walls of the jars. But the fourth jar held the greatest surprise: pure grape wine from 5,000 years ago.</p>
<h2>Presence of wine implies much more</h2>
<p>Initially I did not fully grasp the import of such a discovery. It was only when I vetted the scientific literature on alcoholic beverages in prehistory that I realized the Monte Kronio samples represented the oldest wine known so far for Europe and the Mediterranean region. An incredible surprise, considering that the Southern Anatolia and Transcaucasian region were traditionally believed to be the <a href="https://press.princeton.edu/titles/7591.html">cradle of grape domestication and early viticulture</a>. At the end of 2017, research similar to ours using <a href="https://doi.org/10.1073/pnas.1714728114">Neolithic ceramic samples from Georgia</a> pushed back the discovery of trace of pure grape wine even further, to 6,000-5,800 B.C.</p>
<p>This <a href="https://www.theguardian.com/science/2017/aug/30/traces-of-6000-year-old-wine-discovered-in-sicilian-cave">idea of the “oldest wine”</a> <a href="https://www.cnn.com/2017/08/30/europe/sicily-6000-year-old-wine-discovered/index.html">conveyed in news</a> headlines captured the public’s attention when we <a href="https://www.archaeology.org/news/5872-170825-italy-wine-residue">first published our results</a>.</p>
<p>But what the media failed to convey are the tremendous historical implications that such a discovery has for how archaeologists understand Copper Age Sicilian cultures.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/205978/original/file-20180212-58344-z9466j.jpg?ixlib=rb-1.1.0&rect=485%2C311%2C3179%2C2245&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/205978/original/file-20180212-58344-z9466j.jpg?ixlib=rb-1.1.0&rect=485%2C311%2C3179%2C2245&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/205978/original/file-20180212-58344-z9466j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/205978/original/file-20180212-58344-z9466j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/205978/original/file-20180212-58344-z9466j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/205978/original/file-20180212-58344-z9466j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/205978/original/file-20180212-58344-z9466j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/205978/original/file-20180212-58344-z9466j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A view of Monte Kronio today.</span>
<span class="attribution"><span class="source">Gianni Polizzi, 2018</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>From an economic standpoint, the evidence of wine implies that people at this time and place were cultivating grapevines. Viticulture requires specific terrains, climates and irrigation systems. Archaeologists hadn’t, up to this point, included all these agricultural strategies in their theories about settlement patterns in these Copper Age Sicilian communities. It looks like researchers need to more deeply consider ways these people might have transformed the landscapes where they lived.</p>
<p>The discovery of wine from this time period has an even bigger impact on what archaeologists thought we knew about commerce and the trade of goods across the whole Mediterranean at this time. For instance, Sicily completely lacks metal ores. But the discovery of little copper artifacts – things like daggers, chisels and pins had been found at several sites – shows that Sicilians somehow <a href="https://doi.org/10.1515/opar-2017-0025">developed metallurgy by the Copper Age</a>.</p>
<p>The traditional explanation has been that Sicily engaged in an embryonic commercial relationship with people in the Aegean, especially with the northwestern regions of the Peloponnese. But that doesn’t really make a lot of sense because the Sicilian communities didn’t have much of anything to offer in exchange for the metals. The lure of wine, though, <a href="https://doi.org/10.1558/jmea.v8i1.1">might have been what brought the Aegeans to Sicily</a>, especially if other settlements hadn’t come this far in viticulture yet.</p>
<p>Ultimately, the discovery of wine remnants near gaseous crevices deep inside Monte Kronio adds more support to the hypothesis that the mountain was a sort of prehistoric sanctuary where purification or oracular practices were carried out, taking advantage of the cleansing and intoxicating features of sulfur.</p>
<p>Wine has been known as a magical substance since its <a href="http://doi.org/10.3406/antiq.2009.3735">appearances in Homeric tales</a>. As red as blood, it had the unique power to bring euphoria and an altered state of consciousness and perception. Mixed with the incredible physical stress due to the hot and humid environment, it’s easy to imagine the descent into the darkness of Monte Kronio as a transcendent journey toward the gods. The trek likely ended with death for the weak, maybe with the conviction of immortality for the survivors.</p>
<p>And all of this was written in the grains of 100 milligrams of 6,000-year-old powder.</p><img src="https://counter.theconversation.com/content/89116/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Davide Tanasi does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Growing grapes and making wine come with a lot of implications about a culture’s capabilities. Apparently, Sicily of 6,000 years ago was more sophisticated than archaeologists had given it credit for.Davide Tanasi, Professor of Digital Humanities, Department of History, University of South FloridaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/771732017-05-14T20:14:27Z2017-05-14T20:14:27ZTerahertz spectroscopy: the new tool to help detect art fraud<figure><img src="https://images.theconversation.com/files/168503/original/file-20170509-20757-1vier9w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The pigments can look very different when viewed with terahertz 'eyes'. </span> <span class="attribution"><span class="source">Shutterstock/Garry0305</span></span></figcaption></figure><p>When we look at a painting, how do we know it’s a genuine piece of art?</p>
<p>Everything we see with the unaided eye in a painting – from the Australian outback images of Albert Namatjira or Russell Drysdale, to the vibrant works of Pro Hart – is thanks to the mix of colours that form part of the visible spectrum.</p>
<p>But if we look at the painting in a different way, at a part of the spectrum that is invisible to our eyes, then we can see something very different.</p>
<p>As our <a href="http://dx.doi.org/10.1021/acs.jpca.7b01582">recently published research</a> shows, it could even help us detect art fraud. </p>
<h2>A matter of frequency</h2>
<p>The electromagnetic spectrum ranges from very high-frequency gamma rays down to the extremely low-frequency radiation of just a few hertz. Hertz is the unit of measurement for frequency. </p>
<p>The frequency of colours in the visible spectrum range from blue, at about 800 terahertz (THz), through to red at about 400THz (1 THz = 10<sup>12</sup> or 1,000,000,000,000 hertz).</p>
<p>If we drop to frequencies below the visible spectrum we find the near-infrared at about 300THz and then the mid-infrared at about 30THz.</p>
<p>Then comes the far-infrared and at last we meet the frequencies around 1THz. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/168502/original/file-20170509-20740-1rxqlwr.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/168502/original/file-20170509-20740-1rxqlwr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/168502/original/file-20170509-20740-1rxqlwr.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=243&fit=crop&dpr=1 600w, https://images.theconversation.com/files/168502/original/file-20170509-20740-1rxqlwr.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=243&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/168502/original/file-20170509-20740-1rxqlwr.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=243&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/168502/original/file-20170509-20740-1rxqlwr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=305&fit=crop&dpr=1 754w, https://images.theconversation.com/files/168502/original/file-20170509-20740-1rxqlwr.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=305&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/168502/original/file-20170509-20740-1rxqlwr.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=305&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 terahertz (10¹²) region of the electromagnetic spectrum.</span>
<span class="attribution"><span class="source">The Conversation</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Continuing even further brings us to microwaves and radio waves where frequencies range from the gigahertz down to kilohertz. Thus the terahertz part of the electromagnetic spectrum lies between the radio and the visible parts – in other words, between electronics and photonics.</p>
<p>Things can look very different when viewed with “eyes” that can see in the terahertz range. Some things that are transparent to visible light, such as water, are opaque to terahertz light. </p>
<p>Conversely, some things that visible light won’t penetrate, such as black plastic, readily transmit terahertz radiation.</p>
<p>Intriguingly, two objects that have the same colour when viewed by the unassisted eye may transmit terahertz radiation differently. So their terahertz signal can be used to tell them apart.</p>
<h2>Pigments and colour</h2>
<p>This points to the potential use of terahertz radiation in differentiating paints and pigments. Terahertz spectroscopy can distinguish different pigments with similar colours.</p>
<p>We recently used terahertz spectroscopy to distinguish between three related pigments. All come from a family of chemical compounds called <a href="https://pubchem.ncbi.nlm.nih.gov/compound/Quinacridone#section=Top">quinacridones</a>. These are used widely in producing stable, reproducible pigments that range in colour from red to violet. </p>
<p>Measurements at the University of Wollongong provided the experimental data in the range of 1THz to 10THz. Numerical modelling at Syracuse University (New York) reproduced the experimental data, and gave physical insight into the origin of the features observed.</p>
<p>The combined experimental and theoretical work, <a href="http://dx.doi.org/10.1021/acs.jpca.7b01582">published last month in the Journal of Physical Chemistry</a>, unequivocally demonstrates that terahertz spectroscopy is able to distinguish three different quinacridones.</p>
<p>This brings us to the subject of art authentication – or more importantly, detecting cases of art fraud.</p>
<h2>Art fraud</h2>
<p>Museums, galleries and collectors are typically very protective of their art collections, but terahertz spectroscopy is well suited to examining their works. </p>
<p>While terahertz spectrometers are often located in laboratories, there are also portable models. </p>
<p>Unlike an analysis that requires removing and consuming some material (by reacting it with chemicals, or burning it), there is no contact made with the material, and thus no harm done to the artwork.</p>
<p>The terahertz radiation simply shines on the painting, and the transmitted radiation is measured. The low energy and low density of terahertz radiation means that the painting is not damaged in any way.</p>
<p>This all makes it suitable for examining art in a way that does not damage it and can be performed where it is located – in a gallery, or home, or almost anywhere.</p>
<h2>From theory to practice</h2>
<p>So how can terahertz spectroscopy assist in detecting art fraud in practice?</p>
<p>Here’s an example. Let’s say terahertz spectroscopy picks up a quinacridone pigment in a painting. Quinacridone is an artificial material that was first synthesised in 1935, so the painting must date from 1935 or later. </p>
<p>Any claim that the painting is a work by Leonardo da Vinci (who died in 1519), Vincent van Gogh (died 1890) or Claude Monet (died 1926) could therefore be dismissed. Any claim the the work was by an artist who worked after 1935 could not be so easily disproved on this basis.</p>
<p>Of course, other physical methods than terahertz spectroscopy may be applied to analyse paintings. One direct way to analyse art work is by sophisticated, quantitative measurements of the visible spectrum.</p>
<p>Artworks may also be interrogated by other species of light that lie above the blue end visible spectrum. Here the ultraviolet (uv) photons are higher in energy than visible photons. That means they can put energy into a material that is re-radiated as visible photons. </p>
<p>This is the phenomenon of fluorescence, and uv-fluorescence is an <a href="https://aiccm.org.au/national-news/summary-ultra-violet-fluorescent-materials-relevant-conservation">established tool in art conservation</a>.</p>
<p>Moving further above the ultraviolet, X-rays may be used to examine works of art. For example, X-ray fluorescence at the Australian Synchrotron has been used to <a href="http://www.synchrotron.org.au/aussyncbeamlines/x-ray-fluorescence-microscopy/highlights-xfm/synchrotron-reveals-artists-cover-up">find hidden layers in works by Degas and Streeton</a>.</p>
<h2>A genuine fake?</h2>
<p>There are many aspects to authenticating an artwork, the physical examination being but one of them. </p>
<p>Nonetheless, technical analysis of the materials used – the paints, the canvas, the frames – plays a fundamental role, and that is where terahertz spectroscopy contributes. </p>
<p>But other approaches also play a role. For example, documentation such as records of sales may provide key evidence, as may the more subtle appraisal of style by art historians. </p>
<p>The <a href="https://theconversation.com/the-secret-to-all-great-art-forgeries-50173">perceptions of people</a> who assess and buy art is itself an important factor. The word of the artist might be thought to be definitive, but even this has been overruled by expert opinion, as in the case of <a href="https://theconversation.com/lucian-freud-denied-this-painting-was-his-so-how-could-the-bbc-claim-otherwise-62742">Lucian Freud</a>.</p>
<p>Finally, the legal dimension is critical, as has been reported recently in the <a href="http://www.theage.com.au/entertainment/art-and-design/brett-whiteley-art-fraud-case-convictions-sensationally-quashed-20170427-gvtiip.html">quashing of the art fraud convictions of Peter Gant and Mohamed Siddique</a>. These related to the paintings Blue Lavender Bay, Orange Lavender Bay, and Through the Window. At issue was whether the paintings were the work of Brett Whiteley. </p>
<h2>Other uses</h2>
<p>Of course, art fraud is just one application of terahertz spectroscopy. There are many more. </p>
<p>Able to penetrate paper and cardboard, terahertz radiation can be used to look inside envelopes for contraband, or inside packaged food for contamination. </p>
<p>Terahertz methods have been <a href="https://doi.org/10.1117/1.JBO.18.7.077004">used to assess burns</a> and to monitor the <a href="https://plantmethods.biomedcentral.com/articles/10.1186/s13007-015-0057-7">hydration of plants</a>. </p>
<p>As better terahertz sources, detectors and components are developed, the range of applications will further expand.</p><img src="https://counter.theconversation.com/content/77173/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Roger Lewis works for the University of Wollongong. He receives funding from the Australian Research Council. He is affiliated with the International Society of Infrared, Millimeter, and Terahertz Waves.</span></em></p>Artworks can look very different if you view them with more than the unaided eye, and that can help you spot the fake from the genuine.Roger Lewis, Associate Dean Research, Faculty of Engineering and Information Sciences, University of WollongongLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/606102016-07-07T02:10:52Z2016-07-07T02:10:52ZCan next-generation bomb ‘sniffing’ technology outdo dogs on explosives detection?<figure><img src="https://images.theconversation.com/files/128764/original/image-20160629-15251-9imiqc.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C662%2C433&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Technology is catching up with dogs – and has additional advantages.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/stefz/485663374">Stef</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>With each terrorist attack on another airport, train station or other public space, the urgency to find new ways to detect bombs before they’re detonated ratchets up.</p>
<p>Chemical detection of explosives is a cornerstone of aviation security. Typically called “trace detection,” this approach can find minuscule amounts of residue left behind after someone handles an explosive. A form of this technology called <a href="https://www.crcpress.com/Ion-Mobility-Spectrometry-Third-Edition/Eiceman-Karpas-Jr/p/book/9781439859971">ion mobility spectroscopy</a> is what Transportation Security Administration officers are using when they swab and test your laptop, hands or other items at the airport. In a few seconds, a sample is vaporized, and the resulting chemical ions are separated by molecular size and shape, triggering an alarm if an explosive compound is detected.</p>
<p>But <a href="http://dx.doi.org/10.1016/S0039-9140(00)00565-8">this method</a> is labor-intensive and slow for large volumes of stuff, and its effectiveness can depend on the sampling skill of the officer. It relies on contact sampling, which requires security personnel to have access to surfaces where residue may have been left. That’s not useful if a bomber has no intention of going through a security line and having his personal effects searched.</p>
<p>Some security teams rely on dogs, which can be trained to sniff out explosives using their <a href="http://dx.doi.org/10.1016/S0039-9140(00)00546-4">exquisite sense of smell</a>. But the logistics and training involved with the routine deployment of canines can be arduous, and there are <a href="http://dx.doi.org/10.1016/S0039-9140(00)00565-8">cultural barriers</a> to using dogs to directly screen people.</p>
<p>What researchers have wanted to develop for a long time is a new chemical detection technology that could “sniff” for explosives vapor, much like a canine does. Many efforts over the years fell short as not being sensitive enough. My research team has been working on this problem for nearly two decades – and we’re making good headway.</p>
<h2>More and more sensitive</h2>
<p>The one big hurdle to engineering some kind of technology to rival a dog’s nose is the extremely <a href="http://dx.doi.org/10.1016/j.trac.2012.09.010">low vapor pressures of most explosives</a>. What we call the “equilibrium vapor pressure” of a material is basically a measure of how much of it is in the air, available for detection, under perfect conditions at a specific temperature. </p>
<p>Commonly used by military forces around the world, nitro-organic explosives such as <a href="http://militarynewbie.com/wp-content/uploads/2013/11/TM-9-1300-214-Military-Explosives.pdf">TNT, RDX and PETN</a> have equilibrium vapor pressures in the parts per trillion range. To reliably sniff out related vapors in operational environments, like a busy check-in area of an airport, the detection capability would need to be well below that – down into the <a href="http://dx.doi.org/10.1007/978-94-017-0639-1_46">parts per quadrillion range</a> for many explosives.</p>
<p>These levels have been beyond the capability of trace detection instrumentation. Achieving a 325 parts per quadrillion level of detection is analogous to finding <a href="http://dx.doi.org/10.1038/nature14967">one specific tree on the entire planet Earth</a>.</p>
<p>But recent research has pushed the detection envelope into that part-per-quadrillion range. In 2008, an international team used an advanced ionization technique, called secondary electrospray ionization mass spectrometry, to get <a href="http://dx.doi.org/10.1016/j.jasms.2008.10.006">better than part per trillion level detection</a> of <a href="http://www.rsc.org/chemistryworld/podcast/CIIEcompounds/transcripts/TNT.asp">TNT</a> and <a href="https://www.theguardian.com/world/2010/nov/01/cargo-bomb-plot-petn-explosive">PETN</a>.</p>
<p>In 2012, our research team at Pacific Northwest National Laboratory (<a href="http://www.pnnl.gov">PNNL</a>) achieved direct, real-time detection of <a href="https://en.wikipedia.org/wiki/RDX">RDX</a> vapors at levels below 25 parts per quadrillion using atmospheric flow tube mass spectrometry (<a href="http://dx.doi.org/10.1021/ac302828g">AFT-MS</a>).</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/129393/original/image-20160705-817-17yrloc.gif?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/129393/original/image-20160705-817-17yrloc.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/129393/original/image-20160705-817-17yrloc.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=282&fit=crop&dpr=1 600w, https://images.theconversation.com/files/129393/original/image-20160705-817-17yrloc.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=282&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/129393/original/image-20160705-817-17yrloc.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=282&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/129393/original/image-20160705-817-17yrloc.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=355&fit=crop&dpr=1 754w, https://images.theconversation.com/files/129393/original/image-20160705-817-17yrloc.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=355&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/129393/original/image-20160705-817-17yrloc.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=355&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Schematic diagram of the elegant simplicity of the AFT-MS device.</span>
<span class="attribution"><span class="source">PNNL</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Sensitivity for a mass spectrometer is related to how many of the target molecules can be ionized and transferred into the mass spectrometer for detection. The more complete that process is, the better sensitivity will be. Our AFT-MS scheme is different because it uses time to maximize the benefits of the collisions of the explosive vapor molecules with air ions created from the ion source. It is the extent of reaction between the created ions and the explosives molecules that defines the sensitivity. Using AFT-MS, we’ve now expanded the capability to be able to detect a suite of explosives at <a href="http://dx.doi.org/10.1021/ac402513r">single-digit part per quadrillion level</a>. </p>
<h2>Next step: putting it into practice</h2>
<p>So we’ve moved the state of the art of chemical-based explosives detection into a realm where contact sampling is no longer necessary and instruments can “sniff” for explosives in a manner similar to canines.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/129465/original/image-20160705-791-1o7gq0x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/129465/original/image-20160705-791-1o7gq0x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/129465/original/image-20160705-791-1o7gq0x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=562&fit=crop&dpr=1 600w, https://images.theconversation.com/files/129465/original/image-20160705-791-1o7gq0x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=562&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/129465/original/image-20160705-791-1o7gq0x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=562&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/129465/original/image-20160705-791-1o7gq0x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=706&fit=crop&dpr=1 754w, https://images.theconversation.com/files/129465/original/image-20160705-791-1o7gq0x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=706&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/129465/original/image-20160705-791-1o7gq0x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=706&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">PNNL research scientist Robert Ewing presenting a trace vapor sample to the detector.</span>
<span class="attribution"><span class="source">PNNL</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Instruments that have the vapor detection capability of canines and can also operate continuously open up exciting new security screening possibilities. Trace detection wouldn’t need to rely on direct access to suspicious items for sampling. Engineers could create a noninvasive walk-through explosive detection device, similar to a metal detector.</p>
<p>The real innovation is in the direct detection of the vapor plume, enabled by the extreme sensitivity. There is no longer a need to collect explosive particles for vaporization – as is the case in past trace detection technologies that use loud air jets to dislodge particles from people. Instead, the greater sensitivity means the air could simply be constantly sampled for explosives molecules as people pass through.</p>
<p>This approach would certainly make airport checkpoints less onerous, improving throughput and the passenger experience. These types of devices could also be set up at entrances to airport terminals and other public facilities. It would be a major security leap to be able to detect explosives that are entering a building, not only when passing through a checkpoint.</p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/129081/original/image-20160702-18321-qhd1bc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/129081/original/image-20160702-18321-qhd1bc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=509&fit=crop&dpr=1 600w, https://images.theconversation.com/files/129081/original/image-20160702-18321-qhd1bc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=509&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/129081/original/image-20160702-18321-qhd1bc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=509&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/129081/original/image-20160702-18321-qhd1bc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=639&fit=crop&dpr=1 754w, https://images.theconversation.com/files/129081/original/image-20160702-18321-qhd1bc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=639&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/129081/original/image-20160702-18321-qhd1bc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=639&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Making two measurements – vapor detection via mass spectrometer and visual image via currently deployed body scanner – in the same time and space.</span>
<span class="attribution"><span class="source">PNNL</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>A deployed vapor detection capability would also increase safety by adding a second independent form of information to what scanners have available. Currently, most screening techniques, such as x-ray and <a href="http://science.howstuffworks.com/millimeter-wave-scanner.htm">millimeter wave</a> imaging, are based on spotting anomalies – a TSA operator notices a strange shape in the image. A vapor detection technology would add to their toolkit the ability to identify specific chemicals.</p>
<p>It allows for a two-pronged approach to finding explosives: spotting them on an image and sniffing them out in the vapor plume emitted by a checked bag or a person. It’s like recognizing a person you know but haven’t seen in a long time; both seeing a recent picture and hearing their voice may be necessary to identify them, rather than just one of those pieces of information on its own.</p>
<p>Inspired by the tremendous detection capabilities of dogs, we’ve made remarkable advances toward developing technology that can follow in their footsteps. Deploying vapor analysis for explosives can both enhance security levels and provide a less intrusive screening environment. Continuing research aims to hone the technology and lower its costs so it can be deployed at an airport near you.</p><img src="https://counter.theconversation.com/content/60610/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Atkinson works for the Pacific Northwest National Laboratory, a US Department of Energy multi-program laboratory. He receives funding for research and technical support from a variety of US government sources that fund explosives detection R&D, such as the Department of Homeland Security Science and Technology Division. He is also affiliated with Scientific Workshops Inc. as a trustee. Scientific Workshops is a not for profit organization that runs educational subject matter expert workshops related to explosives detection and other scientific topics. </span></em></p>New research is narrowing the gap, creating technology with the detecting capabilities of canines but without the downsides of relying on a biological system.David Atkinson, Senior Research Scientist, Pacific Northwest National LaboratoryLicensed 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/506032015-11-24T19:16:38Z2015-11-24T19:16:38ZCloudy with a chance of life: how to find alien life on distant exoplanets<figure><img src="https://images.theconversation.com/files/102749/original/image-20151123-423-1xrmlfy.jpg?ixlib=rb-1.1.0&rect=257%2C173%2C3592%2C2197&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The light shining through an exoplanet's atmosphere can give us a hint of whether the planet supports life.</span> <span class="attribution"><a class="source" href="http://hubblesite.org/newscenter/archive/releases/2008/11/image/a/">NASA, ESA, and G. Bacon (STScI)</a></span></figcaption></figure><p>How do you go about hunting for life on <a href="https://theconversation.com/au/topics/exoplanets">another planet</a> elsewhere in our galaxy? A useful starting point is to imagine looking from afar for signs of life on Earth. In a telescope like those we have on Earth, those aliens would likely just see the Earth and sun merged together into a single pale yellow dot. </p>
<p>If they were able to separate the Earth from the sun, they’d still only see a pale blue dot. There would be no way for them to image our planet’s surface and see life roving upon it.</p>
<p>However, those aliens could use <a href="http://loke.as.arizona.edu/%7Eckulesa/camp/spectroscopy_intro.html">spectroscopy</a>, taking Earth’s light and breaking it into its component colours, to figure out what gases make up our atmosphere. Among these gases, they might hope to find a “biomarker”, something unusual and unexpected that could only be explained by the presence of life. </p>
<p>On Earth, the most obvious clue to the presence of life is the abundance of free oxygen in our atmosphere. Why oxygen? Because it is highly reactive and readily combines with other molecules on Earth’s surface and in our oceans. Without the constant resupply coming from life, the free oxygen in the atmosphere would largely disappear.</p>
<h2>Biomarkers</h2>
<p>But the story isn’t quite that simple. Life has existed on Earth for <a href="https://theconversation.com/no-australias-new-fossils-are-not-the-oldest-but-their-value-is-set-in-stone-2994">at least 3.5 billion years</a>. For much of that time, however, oxygen levels were far lower than those seen today. </p>
<p>And oxygen alone is not enough to indicate life; there are many abiological processes that can contribute oxygen to a planet’s atmosphere. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/102745/original/image-20151123-435-1xbqs1a.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/102745/original/image-20151123-435-1xbqs1a.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/102745/original/image-20151123-435-1xbqs1a.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=423&fit=crop&dpr=1 600w, https://images.theconversation.com/files/102745/original/image-20151123-435-1xbqs1a.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=423&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/102745/original/image-20151123-435-1xbqs1a.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=423&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/102745/original/image-20151123-435-1xbqs1a.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=531&fit=crop&dpr=1 754w, https://images.theconversation.com/files/102745/original/image-20151123-435-1xbqs1a.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=531&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/102745/original/image-20151123-435-1xbqs1a.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=531&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 concentration of oxygen in the Earth’s atmosphere over the last billion years. As a reference, the dashed red line shows the present concentration of 21%.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Sauerstoffgehalt-1000mj2.png">Wikimedia</a></span>
</figcaption>
</figure>
<p>For example, ultraviolet light could produce abundant oxygen in the atmosphere of a world covered with water, even if it was devoid of life. </p>
<p>The upshot of this is that a single gas does not a biomarker make. Instead, we must instead look for evidence of a chemical imbalance in a planet’s atmosphere, something that can not be explained by anything other than the presence of life.</p>
<p>Here on Earth, we have one: our atmosphere is not just rich in oxygen, but also contains significant traces of methane. While abundant oxygen or methane could easily be explained on a planet without life, we also know that methane and oxygen react with each other strongly and rapidly. </p>
<p>When you put them together, that reaction will cleanse the atmosphere of whichever is least common. So to maintain the amount of methane in our oxygen-rich atmosphere, you need a huge source of methane, replenishing it against oxygen’s depleting influence. The most likely explanation is life.</p>
<h2>Observing exoplanetary atmospheres</h2>
<p>If we find an exoplanet sufficiently similar to our own, there are several ways in which we could study its atmosphere to search for biomarkers. </p>
<p>When a planet passes directly between us and its host star, a small fraction of the star’s light will pass through the planet’s atmosphere on its way to Earth. If we could zoom in far enough, we would actually see the planet’s atmosphere as a translucent ring surrounding the dark spot that marks the body of the planet.</p>
<p>How much starlight passes through that ring gives us an indication of the atmosphere’s density and composition. What we get is a “<a href="https://theconversation.com/explainer-seeing-the-universe-through-spectroscopic-eyes-37759">transmission spectrum</a>”, which is an absorption spectrum of the planetary atmosphere, illuminated by the background light of the star. </p>
<p>Our technology has only now become capable of collecting and analysing these spectra for the first time. As a result, our interpretation remains strongly limited by our telescopic capabilities and our burgeoning understanding of planetary atmospheres. </p>
<p>Despite the current challenges, the technique continues to develop with great success. In the past few years, astronomers have discovered a wide variety of different chemical species in the atmospheres of some of the biggest and baddest of the known transiting exoplanets.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/102750/original/image-20151123-442-1cq1c6b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/102750/original/image-20151123-442-1cq1c6b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/102750/original/image-20151123-442-1cq1c6b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/102750/original/image-20151123-442-1cq1c6b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/102750/original/image-20151123-442-1cq1c6b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/102750/original/image-20151123-442-1cq1c6b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/102750/original/image-20151123-442-1cq1c6b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/102750/original/image-20151123-442-1cq1c6b.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">Many exoplanets may have no atmosphere at all.</span>
<span class="attribution"><span class="source">NASA/JPL-Caltech</span></span>
</figcaption>
</figure>
<h2>Eclipses</h2>
<p>Another approach involves observing a transiting planet and its star as they orbit one another. The goal here is to collect some observations when the planet is visible (but not in transit), and others when it is eclipsed by its star.</p>
<p>With some effort, astronomers can subtract one observation from the other, effectively cancelling the hugely dominant contribution of light from the star. Once that light is removed, what we have left is the day-side spectrum of the planet. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/102817/original/image-20151123-18230-1b6h2pv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/102817/original/image-20151123-18230-1b6h2pv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/102817/original/image-20151123-18230-1b6h2pv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=480&fit=crop&dpr=1 600w, https://images.theconversation.com/files/102817/original/image-20151123-18230-1b6h2pv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=480&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/102817/original/image-20151123-18230-1b6h2pv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=480&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/102817/original/image-20151123-18230-1b6h2pv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=603&fit=crop&dpr=1 754w, https://images.theconversation.com/files/102817/original/image-20151123-18230-1b6h2pv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=603&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/102817/original/image-20151123-18230-1b6h2pv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=603&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">[Star + Planet] - [Star] = [Planet]</span>
<span class="attribution"><span class="source">NASA/JPL-Caltech/R. Hurt (SSC/Caltech)</span></span>
</figcaption>
</figure>
<h2>The future</h2>
<p>Astronomers are constantly developing new techniques to glean information about exoplanetary atmospheres. One that shows particular potential, especially for the search for planets like our own, is the use of <a href="http://web.gps.caltech.edu/%7Evijay/Papers/Polarisation/Planetary%20Atmospheres/bailey-07.pdf">polarised light</a>. </p>
<p>Most of the light we receive from planets is reflected, originating with the host star. The process of reflection brings with it a subtle benefit - the reflected light gains a degree of polarisation. Different surfaces yield different levels of polarisation, and that polarisation might just hold the key to finding the first oceans beyond the solar system.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/102825/original/image-20151123-18233-1q7zd5o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/102825/original/image-20151123-18233-1q7zd5o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/102825/original/image-20151123-18233-1q7zd5o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=200&fit=crop&dpr=1 600w, https://images.theconversation.com/files/102825/original/image-20151123-18233-1q7zd5o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=200&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/102825/original/image-20151123-18233-1q7zd5o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=200&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/102825/original/image-20151123-18233-1q7zd5o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=251&fit=crop&dpr=1 754w, https://images.theconversation.com/files/102825/original/image-20151123-18233-1q7zd5o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=251&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/102825/original/image-20151123-18233-1q7zd5o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=251&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">By rotating a polarising filter, we can block light of certain polarisation. This is how polarised sunglasses cut the glare from puddles and the ocean on a sunny day.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Mudflats-polariser.jpg">Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>These methods are still severely constrained by two factors: the relative faintness of the exoplanets, and their proximity to their host star. The ongoing story of exoplanetary science is therefore heavily focused on overcoming these observational challenges. </p>
<p>Further down the line, advances in technology and the next generation of telescopes may allow the light from an Earth-like planet to be seen directly. At that point, the task becomes (slightly) easier, in part because the planet can be observed for far longer, rather than just relying on eclipse/transit observations. </p>
<p>But even then, spectroscopy will be the way to go; the planets will still be just pale blue dots.</p>
<h2>What we have seen so far</h2>
<p>The exoplanets we have discovered to date are highly inhospitable to life as we know it. None of the planets studied so far would even be habitable to the most extreme of <a href="http://oceanservice.noaa.gov/facts/extremophile.html">extremophiles</a>. </p>
<p>The planets whose atmospheres we have studied are primarily “hot Jupiters”, giant planets orbiting perilously close to their host stars. As they skim their host’s surface, they whizz around with periods of just a few days, yielding transits and eclipses with every orbit. </p>
<p>Because of the vast amounts of energy they receive from their hosts, many of these “hot Jupiters” are enormous, inflated far beyond the scale of our solar system’s largest planet. That size, that heat and their speed, make them the easiest targets for our observations.</p>
<p>But as our technology has improved, it has also become possible to observe, through painstaking effort, some smaller planets, known as “super-Earths”.</p>
<h2>Atmospheres of distant planets…</h2>
<p>The hot Jupiter <a href="http://exoplanet.eu/catalog/hd_189733_b/">HD189733</a> has one of the best understood planetary atmospheres beyond the solar system. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/102830/original/image-20151123-18271-6v821d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/102830/original/image-20151123-18271-6v821d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/102830/original/image-20151123-18271-6v821d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=429&fit=crop&dpr=1 600w, https://images.theconversation.com/files/102830/original/image-20151123-18271-6v821d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=429&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/102830/original/image-20151123-18271-6v821d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=429&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/102830/original/image-20151123-18271-6v821d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=539&fit=crop&dpr=1 754w, https://images.theconversation.com/files/102830/original/image-20151123-18271-6v821d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=539&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/102830/original/image-20151123-18271-6v821d.jpg?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">Artists impression of the broiling blue marble, HD 189733 b.</span>
<span class="attribution"><span class="source">NASA, ESA, M. Kornmesser</span></span>
</figcaption>
</figure>
<p>Observations by the Hubble Space Telescope, in 2013, suggest a deep-blue world, with a thick atmosphere of silicate vapour. Other studies have shown its atmosphere to contain significant amounts of water vapour, and carbon dioxide. </p>
<p>Overall, however, it appears to be a hydrogen-rich gas giant like Jupiter, albeit super-heated, with cloud tops exceeding 1,000 degrees. Beneath the cloud turps lies a widespread dust layer, featuring silicate and metallic salt compounds. </p>
<p>The young giant planets in the <a href="http://www.space.com/20231-giant-exoplanets-hr-8799-atmosphere-infographic.html">HR8799</a> system appear to have hydrogen-rich but complex atmospheres, with compounds such as methane, carbon monoxide and water. They are likely larger, younger, and hotter versions of our own giant planets - with their own unique subtleties. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/102829/original/image-20151123-18233-yd5ae3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/102829/original/image-20151123-18233-yd5ae3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/102829/original/image-20151123-18233-yd5ae3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/102829/original/image-20151123-18233-yd5ae3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/102829/original/image-20151123-18233-yd5ae3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/102829/original/image-20151123-18233-yd5ae3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/102829/original/image-20151123-18233-yd5ae3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/102829/original/image-20151123-18233-yd5ae3.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"></a>
<figcaption>
<span class="caption">A direct image of the four planets known to orbit the star HR 8799.</span>
<span class="attribution"><span class="source">Ben Zuckerman</span></span>
</figcaption>
</figure>
<p>For the super-Earth <a href="http://www.space.com/14634-alien-planet-steamy-waterworld-gj1214b.html">GJ1214b</a> the lesson is to be careful about making conclusions. Early suggestions that this might be a “water world” or have a cloudless hydrogen atmosphere have since been superseded by models featuring a haze of hydrocarbon compounds (like on <a href="http://www.nasa.gov/mission_pages/cassini/whycassini/cassini20130605_prt.htm">Titan</a>), or grains of potassium salt or zinc sulphide. </p>
<p>While the search for Earth-like planets continues using ground- and space-based telescopes, exoplanetary scientists are eagerly awaiting the launch of the James Webb Space Telescope <a href="https://theconversation.com/au/topics/james-webb-telescope">JWST</a>. </p>
<p>That immense telescope, scheduled for launch in around October 2018, could mark the true beginning of the exciting search for distant atmospheric biomarkers and exoplanetary life.</p><img src="https://counter.theconversation.com/content/50603/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Amanda Bauer received funding from Australian Research Council. She works for the Australian Astronomical Observatory, a division of the Department of Industry, Innovation, and Science. </span></em></p><p class="fine-print"><em><span>Brad Carter and Jonti Horner 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>A hint of oxygen and a whiff of methane in a distant exoplanet’s atmosphere may be the first evidence we discover of alien life.Brad Carter, Professor (Physics), University of Southern QueenslandAmanda Bauer, PhD; Astronomer and Outreach Officer, Australian Astronomical ObservatoryJonti Horner, Vice Chancellor's Senior Research Fellow, University of Southern QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/456182015-08-06T11:46:28Z2015-08-06T11:46:28ZIt’s not Earth 2.0, but our new rocky neighbour is a planet worth watching<figure><img src="https://images.theconversation.com/files/90892/original/image-20150805-22471-13icm0j.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4800%2C2700&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Who goes there? It's very unlikely humans ever will, for sure.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:PIA19833-RockyExoplanet-HD219134b-ArtistConcept-20150730.jpg">NASA/JPL-Caltech</a></span></figcaption></figure><p>The recent discovery of <a href="https://theconversation.com/exoplanet-kepler-452b-offers-a-glimpse-into-the-future-fate-of-our-earth-45144">Earth-like exoplanet Kepler 452-b</a> has caught people’s imagination, with some calling it “<a href="http://www.bbc.co.uk/news/science-environment-33641648">Earth 2.0</a>”. But this has led to another new, potentially far more important exoplanet’s discovery going unnoticed. While it may not have a catchy name, <a href="http://arxiv.org/pdf/1507.08532.pdf">HD 219134 b</a>, the nearest known rocky planet outside our solar system, deserves our attention too.</p>
<p>The planet (“b”) orbits its star HD 219134, which is visible to the human eye near the constellation Cassiopeia, only 21 light-years from the sun. The planet orbits its star alongside three others – like our solar system with Mercury, Venus, Earth and Mars, HD 219134 b has planetary siblings.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/90990/original/image-20150806-5268-18g7cc1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/90990/original/image-20150806-5268-18g7cc1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=318&fit=crop&dpr=1 600w, https://images.theconversation.com/files/90990/original/image-20150806-5268-18g7cc1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=318&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/90990/original/image-20150806-5268-18g7cc1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=318&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/90990/original/image-20150806-5268-18g7cc1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=400&fit=crop&dpr=1 754w, https://images.theconversation.com/files/90990/original/image-20150806-5268-18g7cc1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=400&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/90990/original/image-20150806-5268-18g7cc1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=400&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Say hello: HD 219134 is easy to spot in the night sky.</span>
<span class="attribution"><a class="source" href="https://www.st-andrews.ac.uk/news/archive/2015/title,269166,en.php">NASA</a></span>
</figcaption>
</figure>
<p>What makes HD 219134 b special is how near it is to us – relatively speaking. We can learn a lot about exoplanets like this with techniques that would be difficult or impossible for those at greater distances. </p>
<p>For example, using a technique called <a href="http://www.planetary.org/explore/space-topics/exoplanets/radial-velocity.html">the radial velocity method</a> it’s possible to deduce an exoplanet’s mass by measuring tiny movements of the star caused by the exoplanet’s gravitational pull. This reveals that HD 219134 b has a mass of between four and five times that of the Earth, making it a type of exoplanet known as a “super Earth”.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/-BuwWtMygxU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The radial velocity technique for measuring a planet’s mass. Credit: ESO.</span></figcaption>
</figure>
<p>We can learn more about exoplanets when their orbit takes them between their host star and us. This blocks some of the starlight during the transit, which reveals the planet’s diameter. HD 219134 b is just 1.6 times bigger than the Earth, which together with the measured planetary mass establishes that the planet has the density of rock.</p>
<p>In contrast Kepler 452-b’s mass hasn’t been measured, so it’s not known whether the purported “Earth 2.0” is really a rocky planet at all, although similar-sized planets with measured masses are generally rocky. The fact is, at a distance of 1,400 light years it’s very difficult to measure anything using radial velocity methods.</p>
<h2>Getting to know our neighbour</h2>
<p>So HD 219134 b is now both the nearest known rocky planet and, more importantly, the nearest known planet that transits in front of its star. This kind of planet is particularly exciting for astronomers. If it has an atmosphere, then its nature can be revealed when starlight passes through it during transit. </p>
<p>The atoms and ions making up the atmosphere each absorb starlight at their own characteristic pattern of wavelengths. These tiny amounts of extra absorption can be detected, allowing us to measure the atmosphere’s composition. This is important: it reveals details about processes like volcanism on the planet surface, tells us something of how the planet has evolved, and the atmosphere determines the planet’s surface temperature. </p>
<p>Space telescopes, such as the <a href="http://hubblesite.org/">Hubble Space Telescope</a> and the proposed <a href="https://theconversation.com/uk-satellite-twinkle-will-reveal-atmospheres-of-distant-exoplanets-44945">Twinkle mission</a>, can take these measurements. But the accuracy is limited by the amount of light we collect. Give an astronomer a choice between two similar stars at very different distances from the sun, they will always choose the nearer. A factor of 10 increase in distance means 99% less light, and this is precisely why finding such a nearby transiting planet is a big deal.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/90909/original/image-20150805-22481-c7khj7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/90909/original/image-20150805-22481-c7khj7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/90909/original/image-20150805-22481-c7khj7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/90909/original/image-20150805-22481-c7khj7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/90909/original/image-20150805-22481-c7khj7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/90909/original/image-20150805-22481-c7khj7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/90909/original/image-20150805-22481-c7khj7.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 HD 219134 family portrait: artist’s impression of the system.</span>
<span class="attribution"><a class="source" href="http://www.tng.iac.es/news/2015/07/30/rocky/">Avet Harutyunyan/TNG</a></span>
</figcaption>
</figure>
<h2>What about Earth 2.0?</h2>
<p>The search for exo-Earths has moved on, from science fiction to just science. To place ourselves, our planet and our solar system in their proper galactic and universal context by studying other examples can answer questions which have probably existed since human consciousness arose. </p>
<p>Kepler 452-b has an important place in this new science of <a href="http://www.teachastronomy.com/astropedia/article/Comparative-Planetology">comparative planetology</a>, as one of the first convincing candidates for an Earth-like planet. But it’s just a candidate: there is a lot about Kepler 452-b that we can’t be sure about, as it’s just too far away. On the other hand the relative proximity of HD 219134 b, though it orbits very close to its host star and so is far too hot for liquid water to exist on the surface, provides us better opportunities to unlock its secrets.</p>
<p>One of the most important things the <a href="http://www.nasa.gov/mission_pages/kepler/main/">Kepler observatory</a> has revealed is that small rocky planets appear to be plentiful. This makes it a statistical near-certainty that there are Earth-like planets much closer to us than Kepler 452-b – we just haven’t found them yet. Meanwhile, planets around bright, nearby stars such as HD 219134 constitute one of the most exciting areas of astronomy. </p>
<p>HD 219134 b will teach us much in the next few years about the formation and evolution of a neighbouring planetary system, and this will begin the scientific journey that will ultimately place our own solar system in the wider story of planet formation throughout the Milky Way galaxy.</p><img src="https://counter.theconversation.com/content/45618/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Carole Haswell receives funding from STFC and the Royal Astronomical Society. She has previously received funding from the STFC and its precursors, The Leverhulme Trust, The Nuffield Foundation, NASA, the Space Telescope Science Institute and Zonta International. She is affiliated with the Royal Astronomical Society and the Cleveland and Darlington Astronomical Society.</span></em></p>HD 219134 b may not be a catchy name - but our new planetary neighbour deserves just as much attention as Earth’s cousin, Kepler-452 b.Carole Haswell, Senior Lecturer in Astrophysics, The Open UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/377592015-07-17T05:01:24Z2015-07-17T05:01:24ZExplainer: seeing the universe through spectroscopic eyes<figure><img src="https://images.theconversation.com/files/84324/original/image-20150609-5877-68pmhb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Breaking down the colours in the star light can reveal more about what you are looking at.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/indigoskies/8010736764/">Flickr/Indigo Skies Photography</a></span></figcaption></figure><p>When you look up on a clear night and see stars, what are you really looking at? A twinkling pinprick of light with a hint of colour?</p>
<p>Imagine looking at a starry sky with eyes like prisms that separate the light from each star into its full rainbow of colour. Astronomers have built instruments to do just that, and spectroscopy is one of the most powerful tools in the astronomer’s box.</p>
<p>The technique might not produce the well-known <a href="https://theconversation.com/hubble-in-pictures-astronomers-top-picks-40435">pretty pictures</a> sent down by the Hubble Space Telescope, but for astronomers, a spectrum is worth a thousand pictures. </p>
<p>Visible spectra reveal huge amounts of information about objects in the distant cosmos that we can’t learn any other way. </p>
<h2>So what is spectroscopy?</h2>
<p>Spectroscopy is the process of separating starlight into its constituent wavelengths, like a prism turning sunlight into a rainbow. The familiar colours of the rainbow correspond to different wavelengths of visible light.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/81667/original/image-20150514-28648-18qhpsn.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/81667/original/image-20150514-28648-18qhpsn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/81667/original/image-20150514-28648-18qhpsn.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=89&fit=crop&dpr=1 600w, https://images.theconversation.com/files/81667/original/image-20150514-28648-18qhpsn.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=89&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/81667/original/image-20150514-28648-18qhpsn.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=89&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/81667/original/image-20150514-28648-18qhpsn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=111&fit=crop&dpr=1 754w, https://images.theconversation.com/files/81667/original/image-20150514-28648-18qhpsn.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=111&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/81667/original/image-20150514-28648-18qhpsn.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=111&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 spectrum of visible light. Note the wavelength increases towards the red.</span>
<span class="attribution"><a class="source" href="http://commons.wikimedia.org/wiki/File:Spectre_visible_light_el.png">Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>The human eye is sensitive to the visible spectrum – a narrow range of frequencies among the entire electromagnetic spectrum. The visible spectrum covers wavelengths of roughly 390 nanometers to 780 nanometers (astronomers often use units of <a href="http://www.britannica.com/EBchecked/topic/25257/angstrom-A">Angstroms</a> (10<sup>-10</sup>), so visible light spans 3,900 to 7,800 Angstroms). </p>
<p>Once visible starlight reaches the curved primary mirror of a telescope, it is reflected toward the focal point and can then be directed anywhere. If the light is sent directly to a camera, an image of the night sky is seen on a computer screen as a result.</p>
<p>If the light is instead sent through a spectrograph before it hits the camera, then the light from the astronomical object gets separated into its basic parts.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/84326/original/image-20150609-5871-16mqr44.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/84326/original/image-20150609-5871-16mqr44.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/84326/original/image-20150609-5871-16mqr44.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/84326/original/image-20150609-5871-16mqr44.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/84326/original/image-20150609-5871-16mqr44.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/84326/original/image-20150609-5871-16mqr44.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/84326/original/image-20150609-5871-16mqr44.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/84326/original/image-20150609-5871-16mqr44.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The colours of the spectrum revealed as the light passes through a glass prism.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/23629083@N03/14200678625/">Flickr/final gather</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>A very simple spectrograph was used by Issac Newton in the 1660s when he dispersed light with a glass prism. Modern spectrographs consist of a series of optics, a dispersing element and a camera at the end. The light is digitised and sent to a computer, which astronomers use to inspect and analyse the resulting spectra.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/2bVGr1MV2-8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>The video (above) shows the path of distant starlight through the 4-metre Anglo-Australian Telescope (<a href="http://www.aao.gov.au/about-us/AAT">AAT</a>) and a typical spectrograph, revealing real data at the end.</p>
<h2>What do spectra teach us?</h2>
<p>A spectrum allows astronomers to determine many things about the object being viewed, such as how far away it is, its chemical makeup, age, formation history, temperature and more. While every astronomical object has a unique rainbow fingerprint, some general properties are universal.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/84808/original/image-20150612-1486-1uw6q0p.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/84808/original/image-20150612-1486-1uw6q0p.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/84808/original/image-20150612-1486-1uw6q0p.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=492&fit=crop&dpr=1 600w, https://images.theconversation.com/files/84808/original/image-20150612-1486-1uw6q0p.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=492&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/84808/original/image-20150612-1486-1uw6q0p.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=492&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/84808/original/image-20150612-1486-1uw6q0p.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=618&fit=crop&dpr=1 754w, https://images.theconversation.com/files/84808/original/image-20150612-1486-1uw6q0p.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=618&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/84808/original/image-20150612-1486-1uw6q0p.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=618&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Top shows a spiral galaxy spectrum. Bottom shows non-star-forming galaxy spectrum.</span>
<span class="attribution"><span class="source">Screenshot from Australian Astronomical Observatory video</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Here we examine the galaxy spectra shown in the video. The spectrum of a galaxy is the combined light from its billions of stars and all other radiating matter in the galaxy, such as gas and dust.</p>
<p>In the top spectrum you can see a few strong spikes. These are called “emission lines” and occur at discrete wavelengths due to the atomic structure of atoms as <a href="http://cas.sdss.org/DR5/en/proj/advanced/spectraltypes/energylevels.asp">electrons jump between energy levels</a>.</p>
<p>The hydrogen spectrum is particularly important because 90% of the normal matter in the universe is hydrogen. Because of the details of hydrogen’s atomic structure, we recognise the strong hydrogen-alpha emission line at roughly 7,500 Angstroms in the top spectrum image.</p>
<p>In a galaxy, only the youngest, biggest stars are hot enough to excite surrounding hydrogen gas enough that the electrons populate the third energy level, before falling to the second lowest, thus emitting a hydrogen-alpha photon.</p>
<p>Because of this, we know the strength of the hydrogen-alpha line in a galaxy’s spectrum indicates how many very young stars there are in the galaxy. Since the bottom spectrum shows no hydrogen-alpha emission, we can conclude that the bottom galaxy is not sparking new life in the form of shining stars, while the top galaxy harbours several hard working stellar nurseries.</p>
<p>In the bottom spectrum you can see a number dips. These are called “absorption lines” because they appear in the spectrum if there is anything between the light’s source and the observer on Earth absorbing the light. Absorbing material could be the extended layers of a star or interstellar clouds of gas or dust. </p>
<p>The absorption lines close to each other below 5,000 Angstroms in the bottom spectrum are the <a href="https://en.wikipedia.org/wiki/Calcium#H_and_K_lines">calcium H and K lines</a> and can be used to determine how quickly stars are zooming around the galaxy. </p>
<h2>In a galaxy how far away?</h2>
<p>A basic piece of information derived from a spectrum is the distance to the galaxy, or specifically, how much the light has stretched during its journey to Earth. Because the universe is expanding, the light emitted by the galaxy is stretched toward redder wavelengths as it innocently moves across space. We measure this as redshift.</p>
<p>To determine the exact distance of a galaxy, astronomers measure the well-studied pattern of absorption and emission lines in the observed spectrum and compare it to the laboratory wavelengths of these features on Earth. The difference tells how much the light was stretched, and therefore how long the light was travelling through space, and consequently how far away the galaxy is.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/88723/original/image-20150716-5092-1wujea5.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/88723/original/image-20150716-5092-1wujea5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/88723/original/image-20150716-5092-1wujea5.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=339&fit=crop&dpr=1 600w, https://images.theconversation.com/files/88723/original/image-20150716-5092-1wujea5.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=339&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/88723/original/image-20150716-5092-1wujea5.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=339&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/88723/original/image-20150716-5092-1wujea5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=427&fit=crop&dpr=1 754w, https://images.theconversation.com/files/88723/original/image-20150716-5092-1wujea5.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=427&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/88723/original/image-20150716-5092-1wujea5.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=427&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 absorption lines ‘shift’ the farther away an object is, giving us an indication of its distance from us.</span>
<span class="attribution"><span class="source">Georg Wiora (Dr. Schorsch)/Wikimedia Commons</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>In the top galaxy spectrum mentioned earlier, we measure the strong red emission line of hydrogen-alpha to be at a wavelength of roughly 7,450 Angstroms. Since we know that line has a rest wavelength of 6,563 Angstroms, we calculate a redshift of 0.13, which means the light was travelling for 1.7 billion years before it reached our lucky telescope. The galaxy emitted that light when the universe was roughly 11.8 billion years old.</p>
<h2>Australia’s strength in spectroscopy</h2>
<p>Australia has led the way internationally for spectroscopic technology development for the last 20 years, largely due to the use of fibre optics to direct galaxy light from the telescope structure to the spectrograph.</p>
<p>A huge advantage of using optical fibres is that more than one spectrum can be obtained simultaneously, drastically improving the efficiency of the telescope observing time.</p>
<p>Australian astronomers have also led the world in building robotic technologies to position the individual optical fibres. With these, the AAT and the UK Schmidt Telescopes (both located at <a href="http://rsaa.anu.edu.au/observatories/siding-spring-observatory">Siding Spring Observatory</a> in New South Wales) have collected spectra for a third of all the 2.5 million galaxy spectra that humans have ever observed.</p>
<p>While my own research uses hundreds of thousands of galaxy spectra for individual projects, it still amazes me think that each one of these spectra are composite collections of light created by hundreds of billions of stars gravitationally bound together in a single swirling galaxy, many similar to our own Milky Way home.</p><img src="https://counter.theconversation.com/content/37759/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Amanda Bauer works for the Australian Astronomical Observatory. She previously received funding from the Australian Research Council.</span></em></p>Astronomers can tell a whole lot more about a star or a galaxy if they break up the visible light in a rainbow of colours.Amanda Bauer, PhD; Astronomer and Outreach Officer, Australian Astronomical ObservatoryLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/325412014-11-05T11:10:45Z2014-11-05T11:10:45ZIs your religion ready to meet ET?<figure><img src="https://images.theconversation.com/files/61446/original/35p9v35b-1412987953.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Square away your personal philosophy now; proof of life beyond earth is coming.</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-117721720/photo-ancient-observatory-kokino-macedonia.html?src=lb-29877982">Stargazing image via www.shutterstock.com</a></span></figcaption></figure><p>How will humankind react after astronomers hand over rock-solid scientific evidence for the existence of life beyond the Earth? No more speculating. No more wondering. The moment scientists announce this discovery, everything will change. Not least of all, our philosophies and religions will need to incorporate the new information.</p>
<h2>Searching for signs of life</h2>
<p>Astronomers have now identified <a href="http://exoplanet.eu/">thousands of planets in orbit around other stars</a>. At the current rate of discovery, millions more will be found this century.</p>
<p>Having already found the physical planets, astronomers are now searching for our biological neighbors. Over the next fifty years, they will begin the tantalizing, detailed study of millions of planets, looking for evidence of the presence of life on or below the surfaces or in the atmospheres of those planets. </p>
<p>And it’s very likely that astronomers will find it. Despite the fact that more than one-third of Americans surveyed believe that <a href="http://www.csmonitor.com/Science/2012/0628/More-than-one-third-of-Americans-believe-aliens-have-visited-earth">aliens have already visited Earth</a>, the first evidence of life beyond our planet probably won’t be radio signals, little green men or flying saucers. Instead, a 21st century Galileo, using an enormous, 50-meter-diameter telescope, will collect light from the atmospheres of distant planets, looking for the signatures of biologically significant molecules.</p>
<p>Astronomers filter that light from far away through spectrometers – high-tech prisms that tease the light apart into its many distinct wavelengths. They’re looking for the telltale fingerprints of molecules that would not exist in abundance in these atmospheres in the absence of living things. The spectroscopic data will tell whether a planet’s environment has been altered in ways that point to biological processes at work. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/61450/original/6gh8mvc4-1412989314.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/61450/original/6gh8mvc4-1412989314.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=506&fit=crop&dpr=1 600w, https://images.theconversation.com/files/61450/original/6gh8mvc4-1412989314.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=506&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/61450/original/6gh8mvc4-1412989314.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=506&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/61450/original/6gh8mvc4-1412989314.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=636&fit=crop&dpr=1 754w, https://images.theconversation.com/files/61450/original/6gh8mvc4-1412989314.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=636&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/61450/original/6gh8mvc4-1412989314.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=636&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">What is our place in the universe?</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-186568286/photo-closeup-portrait-young-blonde-woman-dreaming-thinking-about-future-life-on-other-planets.html?src=lb-29877982">Woman image via www.shutterstock.com</a></span>
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</figure>
<h2>If we aren’t alone, who are we?</h2>
<p>With the discovery in a distant planet’s light spectrum of a chemical that could only be produced by living creatures, humankind will have the opportunity to read a new page in the book of knowledge. We will no longer be speculating about whether other beings exist in the universe. We will know that we not alone. </p>
<p>An affirmative answer to the question “Does life exist anywhere else in the universe beyond Earth?” would raise immediate and profoundly important cosmotheological questions about our place in the universe. If extraterrestrial others exist, then my religion and my religious beliefs and practices might not be universal. If my religion is not universally applicable to all extraterrestrial others, perhaps my religion need not be offered to, let alone forced on, all <em>terrestrial</em> others. Ultimately, we might learn some important lessons applicable here at home just from considering the possibility of life beyond our planet.</p>
<p>In my <a href="http://www.springer.com/social+sciences/religious+studies/book/978-3-319-05055-3">book</a>, I investigated the sacred writings of the world’s most widely practiced religions, asking what each religion has to say about the uniqueness or non-uniqueness of life on Earth, and how, or if, a particular religion would work on other planets in distant parts of the universe.</p>
<h2>Extrasolar sinners?</h2>
<p>Let’s examine a seemingly simple yet exceedingly complex theological question: could extraterrestrials be Christians? If Jesus died in order to redeem humanity from the state of sin into which humans are born, does the death and resurrection of Jesus, on Earth, also redeem other sentient beings from a similar state of sin? If so, why are the extraterrestrials sinful? Is sin built into the very fabric of the space and time of the universe? Or can life exist in parts of the universe without being in a state of sin and therefore without the need of redemption and thus without the need for Christianity? Many different solutions to these puzzles involving Christian theology have been put forward. None of them yet satisfy all Christians.</p>
<h2>Mormon worlds</h2>
<p>Mormon scripture clearly teaches that other inhabited worlds exist and that “the inhabitants thereof are begotten sons and daughters unto God” (Doctrines and Covenants 76:24). The Earth, however, is a favored world in Mormonism, because Jesus, as understood by Mormons, lived and was resurrected only on Earth. In addition, Mormon so-called intelligences can only achieve their own spiritual goals during their lives on Earth, not during lifetimes on other worlds. Thus, for Mormons, the Earth might not be the physical center of the universe but it is the most favored place in the universe. Such a view implies that all other worlds are, somehow, lesser worlds than Earth.</p>
<h2>Bahá’í without bias</h2>
<p>Members of the Bahá’í Faith have a view of the universe that has no bias for or against the Earth as a special place or for against humans as a special sentient species. The principles of the Bahá’í Faith – unifying society, abandoning prejudice, equalizing opportunities for all people, eliminating poverty – are about humans on Earth. The Bahá’í faithful would expect any creatures anywhere in the universe to worship the same God as do humans, but to do so according to their own, world-specific ways.</p>
<h2>Light years from Mecca</h2>
<p>The pillars of the faith for Muslims require the faithful to pray five times every day while facing Mecca. Because determining the direction of Mecca correctly could be extremely difficult on a quickly spinning planet millions of light years from Earth, practicing the same faith on another world might not make any sense. Yet the words of the Qu'ran tell us that “Whatever beings there are in the heavens and the earth do prostrate themselves to Allah” (13:15). Can terrestrial Muslims accept that the prophetically revealed religion of Muhammad is intended only for humans on earth and that other worlds would have their own prophets?</p>
<h2>Astronomers as paradigm-shatterers</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/63659/original/r89spnwr-1415137492.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/63659/original/r89spnwr-1415137492.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/63659/original/r89spnwr-1415137492.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=960&fit=crop&dpr=1 600w, https://images.theconversation.com/files/63659/original/r89spnwr-1415137492.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=960&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/63659/original/r89spnwr-1415137492.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=960&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/63659/original/r89spnwr-1415137492.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1207&fit=crop&dpr=1 754w, https://images.theconversation.com/files/63659/original/r89spnwr-1415137492.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1207&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/63659/original/r89spnwr-1415137492.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1207&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Philosophers and scientists have forced worldviews to adapt in the past.</span>
</figcaption>
</figure>
<p>At certain moments throughout history, astronomers’ discoveries have exerted an outsized influence on human culture. Ancient Greek astronomers unflattened the Earth – though many then chose to forget this knowledge. Renaissance scholars Copernicus and Galileo put the Earth in motion around the Sun and moved humans away from the center of the universe. In the 20th century, Edwin Hubble eliminated the very idea that the universe has any center at all. He demonstrated that what the universe has is a beginning in time and that, bizarrely, the universe, the very fabric of three-dimensional space, is expanding. </p>
<p>Clearly, when astronomers offer the world bold new ideas, they don’t mess around. Another such paradigm-shattering new idea may be in the light arriving at our telescopes now. </p>
<p>No matter which (a)theistic background informs your theology, you may have to wrestle with the data astronomers will be bringing to houses of worship in the very near future. You will need to ask: Is my God the God of the entire universe? Is my religion a terrestrial or a universal religion? As people work to reconcile the discovery of extrasolar life with their theological and philosophical worldviews, adapting to the news of life beyond Earth will be discomfiting and perhaps even disruptive.</p><img src="https://counter.theconversation.com/content/32541/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Weintraub does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Astronomers have found thousands of exoplanets and the hunt is on for life beyond Earth. Once biological neighbors are identified, our planet’s philosophies and religions will need to adapt.David Weintraub, Professor of Astronomy, Vanderbilt UniversityLicensed as Creative Commons – attribution, no derivatives.