tag:theconversation.com,2011:/ca-fr/topics/space-oddity-73443/articlesSpace Oddity – La Conversation2021-02-07T19:05:26Ztag:theconversation.com,2011:article/1536502021-02-07T19:05:26Z2021-02-07T19:05:26Z5 twinkling galaxies help us uncover the mystery of the Milky Way’s missing matter<figure><img src="https://images.theconversation.com/files/382678/original/file-20210205-14-1cjaiyy.jpg?ixlib=rb-1.1.0&rect=57%2C38%2C6332%2C3554&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption"></span> <span class="attribution"><span class="license">Author provided</span></span></figcaption></figure><p>We’ve all looked up at night and admired the brightly shining stars. Beyond making a gorgeous spectacle, measuring that light helps us learn about matter in our galaxy, the Milky Way.</p>
<p>When astronomers add up all the ordinary matter detectable around us (such as in galaxies, stars and planets), they find only half the amount expected to exist, based on predictions. This normal matter is “<a href="https://www.space.com/20930-dark-matter.html">baryonic</a>”, which means it’s made up of baryon particles such as protons and neutrons.</p>
<p>But about half of this matter in our galaxy is too dark to be detected by even the most powerful telescopes. It takes the form of cold, dark clumps of gas. In this dark gas is the Milky Way’s “missing” baryonic matter. </p>
<p>In a <a href="https://academic.oup.com/mnras/advance-article-abstract/doi/10.1093/mnras/stab139/6105310">paper</a> published in the Monthly Notices of the Royal Astronomical Society, we detail the discovery of five twinkling far-away galaxies that point to the presence of an unusually shaped gas cloud in the Milky Way. We think this cloud may be linked to the missing matter.</p>
<h2>Finding what we can’t see</h2>
<p>Stars twinkle because of turbulence in our atmosphere. When their light reaches Earth, it gets bent as it bounces through different layers of the atmosphere.</p>
<p>Rarely, galaxies can twinkle too, due to the turbulence of gas in the Milky Way. We see this twinkling because of the luminous cores of distant galaxies named “quasars”.</p>
<p>Astronomers can use quasars a bit like backlights, to reveal the presence of clumps of gas around us that would otherwise be impossible to see. The challenge, however, is that it is very rare to catch quasars twinkling.</p>
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Read more:
<a href="https://theconversation.com/curious-kids-why-do-stars-twinkle-81188">Curious Kids: Why do stars twinkle?</a>
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<p>This is where the <a href="https://theconversation.com/the-australian-square-kilometre-array-pathfinder-finally-hits-the-big-data-highway-71217">Australian Square Kilometre Array Pathfinder</a> (ASKAP) comes in. This highly sensitive telescope can view an area about the size of the Southern Cross and detect tens of thousands of distant galaxies, including quasars, in a single observation. </p>
<p>Using ASKAP, we looked at the same patch of sky seven times. Of the 30,000 galaxies we could see, six were twinkling strongly. Surprisingly, five of these were arranged in a long, thin straight line.</p>
<p>Analysis showed we’d captured an invisible clump of gas between us and the galaxies. As light from the galaxies passed through the gas cloud, they appeared to twinkle. </p>
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<p> At the centre is one of the strongly twinkling galaxies. The colours represent brightness, as it fluctuates between shining brightly (red) and more faintly (blue). </p>
<h2>A clump of gas ten light years away</h2>
<p>The cloud of gas we detected was inside the Milky Way, about ten light years away from Earth. For reference, one light year is 9.7 trillion kilometres. </p>
<p>That means light from those twinkling galaxies travelled billions of light years towards Earth, only to be disrupted by the cloud during the last ten years of its journey. </p>
<p>By observing the sky positions of not just the five twinkling galaxies, but also tens of thousands of non-twinkling ones, we were able to draw a boundary around the gas cloud.</p>
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<img alt="" src="https://images.theconversation.com/files/380428/original/file-20210125-19-12u4kcg.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/380428/original/file-20210125-19-12u4kcg.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=476&fit=crop&dpr=1 600w, https://images.theconversation.com/files/380428/original/file-20210125-19-12u4kcg.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=476&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/380428/original/file-20210125-19-12u4kcg.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=476&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/380428/original/file-20210125-19-12u4kcg.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=599&fit=crop&dpr=1 754w, https://images.theconversation.com/files/380428/original/file-20210125-19-12u4kcg.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=599&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/380428/original/file-20210125-19-12u4kcg.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=599&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">We were intrigued by the sky positions of the twinkling galaxies in our ASKAP observations. Each black dot above represents a brightly-shining, distant object.</span>
<span class="attribution"><span class="source">Yuanming Wang</span></span>
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<p>We found it was very straight, the same length as four Moons side-by-side, and only two “<a href="https://earthsky.org/astronomy-essentials/sky-measurements-degrees-arc-minutes-arc-seconds">arcminutes</a>” in width. This is so thin it’s the equivalent of looking at a strand of hair held at arm’s length. </p>
<p>This is the first time astronomers have been able to calculate the geometry and physical properties of a gas cloud in this way. But where did it come from? And what gave it such an unusual shape?</p>
<h2>It’s freezing out there</h2>
<p>Astronomers have predicted that when a star passes too close to a black hole, the extreme forces from the black hole will pull it apart, resulting in a long, thin gas stream. </p>
<p>But there are no massive black holes near that cloud of gas — the <a href="https://www.bbc.com/news/science-environment-52560812">closest one we know about</a> is more than 1,000 light years from Earth.</p>
<p>So we propose another theory: that a hydrogen “snow cloud” was disrupted and stretched out by gravitational forces from a nearby star, turning into a long thin gas cloud. </p>
<p>Snow clouds have only been studied as theoretical possibilities and are almost impossible to detect. But they would be so cold that droplets of hydrogen gas within them could freeze solid. </p>
<p>Some astronomers believe snow clouds make up part of the missing matter in the Milky Way.</p>
<p>It’s incredibly exciting for us to have measured an invisible clump of gas in such detail, using the ASKAP telescope. In the future we plan to repeat our experiment on a much larger scale and hopefully create a “cloud map” of the Milky Way. </p>
<p>We’ll then be able to work out how many other gas clouds are out there, how they’re distributed and what role they might have played in the evolution of the Milky Way.</p>
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Read more:
<a href="https://theconversation.com/half-the-matter-in-the-universe-was-missing-we-found-it-hiding-in-the-cosmos-138569">Half the matter in the universe was missing – we found it hiding in the cosmos</a>
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<img src="https://counter.theconversation.com/content/153650/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Yuanming Wang receives support from China Scholarship Council, and as a Graduate Student with the University of Sydney and CSIRO Astronomy and Space Science.</span></em></p><p class="fine-print"><em><span>Tara Murphy works for the University of Sydney. She receives funding from the Australian Research Council and is an Associate Investigator in the OzGrav Centre of Excellence for Gravitational Wave Discovery.</span></em></p>Thanks to the discovery of five twinkling galaxies in a rare alignment, astronomers have been able to calculate — for the first time — the properties and geometry of an invisible gas cloud in space.Yuanming Wang, PhD student, University of SydneyTara Murphy, Professor, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1545632021-02-04T07:06:04Z2021-02-04T07:06:04ZThese distant ‘baby’ black holes seem to be misbehaving — and experts are perplexed<figure><img src="https://images.theconversation.com/files/382414/original/file-20210204-14-2u8inb.png?ixlib=rb-1.1.0&rect=0%2C0%2C5476%2C2311&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Dr Natasha Hurley-Walker (Curtin / ICRAR) and The GLEAM Team</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p>Radio images of the sky have revealed hundreds of “baby” and supermassive black holes in distant galaxies, with the galaxies’ light bouncing around in unexpected ways. </p>
<p>Galaxies are vast cosmic bodies, tens of thousands of light years in size, made up of gas, dust, and stars (like our Sun). </p>
<p>Given their size, you’d expect the amount of light emitted from galaxies would change slowly and steadily, over timescales far beyond a person’s lifetime. </p>
<p>But our research, <a href="https://academic.oup.com/mnras/article-abstract/501/4/6139/6031337?redirectedFrom=fulltext">published</a> in the Monthly Notices of the Royal Astronomical Society, found a surprising population of galaxies whose light changes much more quickly, in just a matter of years.</p>
<h2>What is a radio galaxy?</h2>
<p>Astronomers think there’s a supermassive black hole at the centre of most galaxies. Some of these are “active”, which means they emit a lot of radiation. </p>
<p>Their powerful gravitational fields pull in matter from their surroundings and rip it apart into an orbiting donut of hot plasma called an “accretion disk”.</p>
<p>This disk orbits the black hole at nearly the speed of light. Magnetic fields accelerate high-energy particles from the disk in long, thin streams or “jets” along the rotational axes of the black hole. As they get further from the black hole, these jets blossom into large mushroom-shaped clouds or “lobes”.</p>
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<a href="https://images.theconversation.com/files/382398/original/file-20210204-18-coa4jt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Radio galaxy with bright yellow core, long thin jets extending in opposite directions and large red lobes" src="https://images.theconversation.com/files/382398/original/file-20210204-18-coa4jt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/382398/original/file-20210204-18-coa4jt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=426&fit=crop&dpr=1 600w, https://images.theconversation.com/files/382398/original/file-20210204-18-coa4jt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=426&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/382398/original/file-20210204-18-coa4jt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=426&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/382398/original/file-20210204-18-coa4jt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=536&fit=crop&dpr=1 754w, https://images.theconversation.com/files/382398/original/file-20210204-18-coa4jt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=536&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/382398/original/file-20210204-18-coa4jt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=536&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 radio galaxy Hercules A has an active supermassive black hole at its centre. Here it is pictured emitting high energy particles in jets expanding out into radio lobes.</span>
<span class="attribution"><span class="source">NASA/ESA/NRAO</span></span>
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<p>This entire structure is what makes up a radio galaxy, so called because it gives off a lot of radio-frequency radiation. It can be hundreds, thousands or even millions of light years across and therefore can take aeons to show any dramatic changes.</p>
<p>Astronomers have long questioned why some radio galaxies host enormous lobes, while others remain small and confined. Two theories exist. One is that the jets are held back by dense material around the black hole, often referred to as frustrated lobes. </p>
<p>However, the details around this phenomenon remain unknown. It’s still unclear whether the lobes are only temporarily confined by a small, extremely dense surrounding environment — or if they’re slowly pushing through a larger but less dense environment.</p>
<p>The second theory to explain smaller lobes is the jets are young and have not yet extended to great distances. </p>
<h2>Old ones are red, babies are blue</h2>
<p>Both young and old radio galaxies can be identified by a clever use of modern radio astronomy: looking at their “radio colour”.</p>
<p>We looked at data from the <a href="https://theconversation.com/what-the-universe-looks-like-when-viewed-with-radio-eyes-66381">GaLactic and Extragalactic All Sky MWA (GLEAM) survey</a>, which sees the sky at 20 different radio frequencies, giving astronomers an unparalleled “radio colour” view of the sky. </p>
<p>From the data, baby radio galaxies appear blue, which means they’re brighter at higher radio frequencies. Meanwhile the old and dying radio galaxies appear red and are brighter in the lower radio frequencies.</p>
<p>We identified 554 baby radio galaxies. When we looked at identical data taken a year later, we were surprised to see 123 of these were bouncing around in their brightness, appearing to flicker. This left us with a puzzle. </p>
<p>Something more than one light year in size can’t vary so much in brightness over less than one year without breaking the laws of physics. So, either our galaxies were far smaller than expected, or something else was happening. </p>
<p>Luckily, we had the data we needed to find out.</p>
<p>Past research on the variability of radio galaxies has used either a small number of galaxies, archival data collected from many different telescopes, or was conducted using only a single frequency. </p>
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Read more:
<a href="https://theconversation.com/weve-mapped-a-million-previously-undiscovered-galaxies-beyond-the-milky-way-take-the-virtual-tour-here-148442">We've mapped a million previously undiscovered galaxies beyond the Milky Way. Take the virtual tour here.</a>
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<p>For our research, we surveyed more than 21,000 galaxies over one year across multiple radio frequencies. This makes it the first “spectral variability” survey, enabling us to see how galaxies change brightness at different frequencies. </p>
<p>Some of our bouncing baby radio galaxies changed so much over the year we doubt they are babies at all. There’s a chance these compact radio galaxies are actually angsty teens rapidly growing into adults much faster than we expected.</p>
<p>While most of our variable galaxies increased or decreased in brightness by roughly the same amount across all radio colours, some didn’t. Also, 51 galaxies changed in both brightness <em>and</em> colour, which may be a clue as to what causes the variability.</p>
<h2>3 possibilities for what is happening</h2>
<p><strong>1) Twinkling galaxies</strong></p>
<p>As light from stars travels through Earth’s atmosphere, it is distorted. This creates the twinkling effect of stars we see in the night sky, called “scintillation”. The light from the radio galaxies in this survey passed through our Milky Way galaxy to reach our telescopes on Earth. </p>
<p>Thus, the gas and dust within our galaxy could have distorted it the same way, resulting in a twinkling effect. </p>
<p><strong>2) Looking down the barrel</strong></p>
<p>In our three-dimensional Universe, sometimes black holes shoot high energy particles directly towards us on Earth. These radio galaxies are called “blazars”. </p>
<p>Instead of seeing long thin jets and large mushroom-shaped lobes, we see blazars as a very tiny bright dot. They can show extreme variability in short timescales, since any little ejection of matter from the supermassive black hole itself is directed straight towards us. </p>
<p><strong>3) Black hole burps</strong></p>
<p>When the central supermassive black hole “burps” some extra particles they form a clump slowly travelling along the jets. As the clump propagates outwards, we can detect it first in the “radio blue” and then later in the “radio red”.</p>
<p>So we may be detecting giant black hole burps slowly travelling through space. </p>
<h2>Where to now?</h2>
<p>This is the first time we’ve had the technological ability to conduct a large-scale variability survey over multiple radio colours. The results suggest our understanding of the radio sky is lacking and perhaps radio galaxies are more dynamic than we expected. </p>
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<img alt="Artist's impression of the SKA: on the left multiple dishes scattered around representing SKA_MID and on the right a large collection of antennas representing SKA_LOW." src="https://images.theconversation.com/files/382417/original/file-20210204-18-kxrm5w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/382417/original/file-20210204-18-kxrm5w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/382417/original/file-20210204-18-kxrm5w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/382417/original/file-20210204-18-kxrm5w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/382417/original/file-20210204-18-kxrm5w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/382417/original/file-20210204-18-kxrm5w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/382417/original/file-20210204-18-kxrm5w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=377&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">An artist’s impression of the SKA telescope. On the left is SKA-Mid, fading into SKA-Low on the right.</span>
<span class="attribution"><span class="source">SKAO/ICRAR/SARAO</span></span>
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<p>As the next generation of telescopes come online, in particular the Square Kilometre Array (SKA), astronomers will build up a dynamic picture of the sky over many years.</p>
<p>In the meantime, it’s worth watching these weirdly behaving radio galaxies and keeping a particularly close eye on the bouncing babies, too.</p>
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Read more:
<a href="https://theconversation.com/the-worlds-oldest-story-astronomers-say-global-myths-about-seven-sisters-stars-may-reach-back-100-000-years-151568">The world's oldest story? Astronomers say global myths about 'seven sisters' stars may reach back 100,000 years</a>
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<img src="https://counter.theconversation.com/content/154563/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kathryn Ross receives funding from the Australian Research Training Program (RTP), funded by the Australian Government. </span></em></p><p class="fine-print"><em><span>Dr Natasha Hurley-Walker is supported by an Australian Research Council Future Fellowship (project number FT190100231), funded by the Australian Government.</span></em></p>Some of the baby radio galaxies found may not be ‘babies’ at all. Rather, they may be ‘angsty teens’, rapidly growing into adults much faster than researchers had anticipated.Kathryn Ross, PhD Student, Curtin UniversityNatasha Hurley-Walker, Radio Astronomer, Curtin UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1479112020-10-13T01:54:04Z2020-10-13T01:54:04ZThis mysterious ‘exotic stellar peacock’ may open the door to a realm of physics only ever glimpsed<figure><img src="https://images.theconversation.com/files/363067/original/file-20201013-19-s0fxyv.jpg?ixlib=rb-1.1.0&rect=24%2C13%2C1253%2C1264&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">ESO/Callingham et al.</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>An astronomical discovery is shedding new light on an exquisitely-formed star system in our own Milky Way galaxy, featuring two <a href="https://astronomy.swin.edu.au/cosmos/w/wolf-rayet+star">Wolf-Rayet stars</a>. These stars are short-lived and consequently very rare, with only a <a href="http://www.physics.usyd.edu.au/%7Egekko/">few hundred confirmed</a> among our galaxy’s one hundred billion or so stars.</p>
<p>Research <a href="https://academic.oup.com/mnras/article/498/4/5604/5917924">published</a> by our team in the Monthly Notices of the Royal Astronomical Society offers a closer look at not one, but two Wolf-Rayet stars, in a binary star system named Apep, about 8000 light years away from Earth.</p>
<p>Wolf-Rayets are often more than 20 times the mass of our sun. They’re fiercely hot, bright and can emit more radiation than a million normal stars. In fact, they’re so luminous they fly apart under their own glare — shedding huge amounts of mass through intense stellar winds and driving elements such as helium, oxygen and carbon into space. </p>
<p>Apep, named after the serpentine Egyptian god of chaos, was first <a href="https://www.sydney.edu.au/news-opinion/news/2018/11/20/doomed-star-in-milky-way-threatens-rare-gamma-ray-burst.html">announced</a> by my team in 2018.
With the new findings from a paper led by recent University of Sydney graduate from my group, Yinuo Han, we threw everything we had at the seemingly inexplicable physics driving this exotic peacock of the stellar kingdom. </p>
<h2>Apep’s dance caught on camera</h2>
<p>Finding any Wolf-Rayet star is a one-in-a-billion event, only possible because their extreme properties act as a beacon visible across the galaxy. In Apep, we find a pair of these rare stars nestled in an orbit, the only example of a binary Wolf-Rayet ever verified.</p>
<p>Their ferocious radiation drives the outer layers of the star off into space, where the material, particularly the carbon, is able to cool and condense into a plume of grains — forming a literal pillar of stardust. </p>
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Read more:
<a href="https://theconversation.com/experts-solve-the-mystery-of-a-giant-x-shaped-galaxy-with-a-monster-black-hole-as-its-engine-138205">Experts solve the mystery of a giant X-shaped galaxy, with a monster black hole as its engine</a>
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<p>In the case of the binary star Apep, however, as the two stars orbit one another, this dust gets twisted and sculpted into a vast glowing sooty tail. Both the geometric form and the motion of this dust encodes the physics of the star’s orbit, as well as the speed of winds. </p>
<p>Using high-resolution imaging techniques, we revealed the form of the glowing plume. By returning to Apep for three consecutive years, subtle differences could be seen in the motion of the dust tail. </p>
<p>Despite the vast distance over which we observed the system, the incredible power of modern telescopes and imaging technologies allowed us to capture Apep’s dance.</p>
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<h2>A potential first for our Milky Way?</h2>
<p>Analysing these data, we produced and a model that matches Apep’s intricate spiral geometry in amazing detail. However the increasing clarity of the imagery only served to double down on the underlying enigma enshrouding the system.</p>
<p>Flouting rules that generally govern other wind-driven dust plumes, Apep’s dust tail seemed to float along at its own slow pace, in open defiance to the the extreme winds that should be driving it. This was hard to fathom, as Wolf-Rayet winds are more than a billion times more powerful than our own solar wind.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/363070/original/file-20201013-23-857waa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="The Apep binary star system." src="https://images.theconversation.com/files/363070/original/file-20201013-23-857waa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/363070/original/file-20201013-23-857waa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/363070/original/file-20201013-23-857waa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/363070/original/file-20201013-23-857waa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/363070/original/file-20201013-23-857waa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/363070/original/file-20201013-23-857waa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/363070/original/file-20201013-23-857waa.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">Wolf-Rayet stars have some of the strongest known winds in the galaxy.</span>
<span class="attribution"><span class="source">European Southern Observatory</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>After double-checking for possible errors, we were forced to accept the dust spiral was, indeed, expanding four times slower than the measured stellar winds. And so, we were confronted with something unheard of in other Wolf-Rayet double star systems; something requiring new physics to understand. </p>
<p>The only explanation that remained was that Apep’s plume was somehow sheltered within its own, more gentle wind. This two-speed model of wind is is <a href="https://cds.cern.ch/record/473405/files/0010581.pdf">theoretically possible</a> if the star that launches the wind has a peculiar property: rapid rotation. </p>
<p>If it’s spinning very fast on its axis, it’s possible this could launch a slow wind in one direction, say around the equator, while maintaining a fast wind closer to the poles. </p>
<p>This opens the door into a realm of fascinating physics that has only been glimpsed by astronomers before.</p>
<h2>Burn bright, live fast, die young</h2>
<p>Wolf-Rayet stars are, by definition, at the end of their life cycle. In perhaps only a few tens of thousands of years — nobody knows exactly when —they’re destined to explode as supernova, releasing a titanic amount of energy and matter into the galaxy and leaving a remnant black hole or neutron star. </p>
<p>It’s here the critical issue of the star’s rapid rotation comes to centre stage. A normal supernova carries few impacts and consequences beyond its immediate stellar neighbourhood. But when the precursor star is a rapid rotator, this can tip the physics into a different domain entirely: that of a <a href="https://astronomy.swin.edu.au/cosmos/g/gamma+Ray+burst">gamma-ray burst</a>. </p>
<p>Here, bursts of raw fury erupt from the rotational poles with such violence they are visible clean across the observable universe. </p>
<p>Being extremely rare, <a href="https://imagine.gsfc.nasa.gov/science/objects/bursts1.html">gamma-ray bursts</a> have never been observed in our galaxy. Calculations imply a direct strike from such an intense burst of radiation, even at a considerable distance off in the deeps of the galaxy, could have real consequences for life here on Earth. </p>
<p>It might cause a range of problems, such as <a href="https://www.popularmechanics.com/space/deep-space/a14487408/how-a-gamma-ray-burst-could-cause-mass-extinction-from-billions-of-miles-away/">ozone depletion and acid rain</a>. Some <a href="https://www.nature.com/news/2003/030922/full/news030922-7.html">studies argue</a> such a strike may have caused the Ordovician–Silurian extinction event in the fossil record — the second-largest (percentage wise) of Earth’s five major extinction events. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/solving-the-mystery-of-the-wimpy-supernova-104726">Solving the mystery of the wimpy supernova</a>
</strong>
</em>
</p>
<hr>
<p>Fortunately for us, in the case of Apep, we’re definitely not in the firing line. If a gamma-ray strike were to be generated, it would be pointed harmlessly off in a direction away from Earth. </p>
<p>If the link to a gamma-ray burst progenitor can be firmly established, this would capture an elusive phenomena formerly only known at cosmological distances. Either way, the future for studies of this system are bright indeed.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/eH7x45BkQdM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">University of Sydney undergraduate unlocked Yinuo Han conducted research on Apep, a Wolf-Rayet binary star system 8000 light years from Earth. Credit: Yinuo Han.</span></figcaption>
</figure><img src="https://counter.theconversation.com/content/147911/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Peter Tuthill receives funding from the Australian Research Council and the University of Sydney. </span></em></p>Surprising findings on an exquisite and huge star system in our Milky Way suggest future potential for an extremely rare gamma-ray burst. This event has never been observed in our galaxy.Peter Tuthill, Astrophysicist, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1464072020-09-20T19:42:37Z2020-09-20T19:42:37ZIf there is life on Venus, how could it have got there? Origin of life experts explain<figure><img src="https://images.theconversation.com/files/358781/original/file-20200918-18-1xkxztj.jpg?ixlib=rb-1.1.0&rect=71%2C35%2C5919%2C3458&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>The <a href="https://theconversation.com/life-on-venus-traces-of-phosphine-may-be-a-sign-of-biological-activity-146093">recent discovery of phosphine</a> in the atmosphere of Venus is exciting, as it may serve as a potential sign of life (among other possible explanations). </p>
<p>The researchers, who <a href="https://www.nature.com/articles/s41550-020-1174-4">published their findings in Nature Astronomy</a>, couldn’t really explain how the phosphine got there. </p>
<p>They explored all conceivable possibilities, including lightning, volcanoes and even delivery by meteorites. But each source they modelled couldn’t produce the amount of phosphine detected.</p>
<p>Most phosphine in Earth’s atmosphere is produced by living microbes. So the possibility of life on Venus producing phosphine can’t be ignored. </p>
<p>But the researchers, led by UK astronomer Jane Greaves, say their discovery “is not robust evidence for life” on Venus. Rather, it’s evidence of “anomalous and unexplained chemistry”, of which biological processes are just one possible origin.</p>
<p>If life were to exist on Venus, how could it have come about? Exploring the origins of life on Earth might shed some light.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/life-on-venus-traces-of-phosphine-may-be-a-sign-of-biological-activity-146093">Life on Venus? Traces of phosphine may be a sign of biological activity</a>
</strong>
</em>
</p>
<hr>
<h2>The ingredients for life (as we know it)</h2>
<p>Understanding how life formed on Earth not only helps us understand our own origins, but could also provide insight into the key ingredients needed for life, as we know it, to form. </p>
<p>The details around the origins of life on Earth are still shrouded in mystery, with <a href="https://www.scientificamerican.com/article/lifes-origins-by-land-or-sea-debate-gets-hot/">multiple competing scientific theories</a>. But most theories include a common set of environmental conditions considered vital for life. These are: </p>
<p><strong>Liquid water</strong></p>
<p>Water is needed to dissolve the molecules needed for life, to facilitate their chemical reactions. Although other solvents (such as methane) have been suggested to potentially support life, water is most likely. This is because it <a href="http://sitn.hms.harvard.edu/uncategorized/2019/biological-roles-of-water-why-is-water-necessary-for-life/">can dissolve a huge range of different molecules</a> and is found throughout the universe.</p>
<p><strong>Mild temperatures</strong> </p>
<p>Temperatures higher than 122°C destroy most complex organic molecules. This would make it almost impossible for carbon-based life to form in very hot environment. </p>
<p><strong>A process to concentrate molecules</strong> </p>
<p>As the origin of life would have required a large amount of organic molecules, a process to concentrate organics from the diluted surrounding environment would be required – either through absorption onto mineral surfaces, evaporation or floating on top of water in oily slicks. </p>
<p><strong>A complex natural environment</strong></p>
<p>For life to have originated, there would have had to be a complex natural environment wherein a diverse range of conditions (temperature, pH and salt concentrations) could create chemical complexity. Life itself is incredibly complex, so even the most primitive versions would need a complex environment to originate.</p>
<p><strong>Trace metals</strong></p>
<p>A range of trace metals, amassed through water-rock interactions, would be needed to promote the formation of organic molecules.</p>
<p>So if these are the conditions required for life, what does that tell us about the likelihood of life forming on Venus? </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/358787/original/file-20200918-14-6vka30.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Photo of Venus" src="https://images.theconversation.com/files/358787/original/file-20200918-14-6vka30.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/358787/original/file-20200918-14-6vka30.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=615&fit=crop&dpr=1 600w, https://images.theconversation.com/files/358787/original/file-20200918-14-6vka30.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=615&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/358787/original/file-20200918-14-6vka30.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=615&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/358787/original/file-20200918-14-6vka30.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=773&fit=crop&dpr=1 754w, https://images.theconversation.com/files/358787/original/file-20200918-14-6vka30.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=773&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/358787/original/file-20200918-14-6vka30.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=773&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Venus has 90 times the atmospheric pressure of Earth.</span>
<span class="attribution"><span class="source">NASA</span></span>
</figcaption>
</figure>
<h2>It’s unlikely today …</h2>
<p>The possibility of life as we know it forming on the surface of present-day Venus is incredibly low. An average surface temperature above 400°C means the surface can’t possibly have liquid water and this heat would also destroy most organic molecules. </p>
<p>Venus’s milder upper atmosphere, however, has temperatures low enough for water droplets to form and thus could potentially be suitable for the formation of life. </p>
<p>That said, this environment has its own limitations, such as clouds of sulfuric acid which would destroy any organic molecules not protected by a cell. For example, on Earth, molecules such as DNA are rapidly destroyed by acidic conditions, although some <a href="https://sciencing.com/types-bacteria-living-acidic-ph-9296.html">bacteria can survive</a> in extremely acidic environments.</p>
<p>Also, the constant falling of water droplets from Venus’s atmosphere down to its extremely hot surface would destroy any unprotected organic molecules in the droplets. </p>
<p>Beyond this, with no surfaces or mineral grains in the Venusian atmosphere on which organic molecules could concentrate, any chemical building blocks for life would be scattered through a diluted atmosphere – making it incredibly difficult for life to form. </p>
<h2>… but possibly less unlikely in the past</h2>
<p>Bearing all this in mind, if atmospheric phosphine is indeed a sign of life on Venus, there are three main explanations for how it could have formed. </p>
<p>Life may have formed on the planet’s surface when its conditions were very different to now. </p>
<p>Modelling suggests the surface of early Venus was very similar to early Earth, with lakes (or even oceans) of water and <a href="https://www.nasa.gov/feature/goddard/2016/nasa-climate-modeling-suggests-venus-may-have-been-habitable">mild conditions</a>. This was before a runaway greenhouse effect turned the planet into the hellscape it is today.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/358782/original/file-20200918-16-1s8z2gp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Computer generated surface view of Eistla Regio region on Venus." src="https://images.theconversation.com/files/358782/original/file-20200918-16-1s8z2gp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/358782/original/file-20200918-16-1s8z2gp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=467&fit=crop&dpr=1 600w, https://images.theconversation.com/files/358782/original/file-20200918-16-1s8z2gp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=467&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/358782/original/file-20200918-16-1s8z2gp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=467&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/358782/original/file-20200918-16-1s8z2gp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=587&fit=crop&dpr=1 754w, https://images.theconversation.com/files/358782/original/file-20200918-16-1s8z2gp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=587&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/358782/original/file-20200918-16-1s8z2gp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=587&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This is a computer-generated picture of the Eistla Regio region on Venus’s surface.</span>
<span class="attribution"><span class="source">NASA</span></span>
</figcaption>
</figure>
<p>If life formed back then, it might have adapted to spread into the clouds. Then, when intense climate change boiled the oceans away – killing all surface-based life – microbes in the clouds would have become the last outpost for life on Venus.</p>
<p>Another possibility is that life in Venus’s atmosphere (if there is any) came from Earth. </p>
<p>The planets of our inner solar system have been documented to exchange materials in the past. When meteorites crash into a planet, they can send that planet’s rocks hurtling into space where they occasionally intersect with the orbits of other planets.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/meteorites-from-mars-contain-clues-about-the-red-planets-geology-130104">Meteorites from Mars contain clues about the red planet's geology</a>
</strong>
</em>
</p>
<hr>
<p>If this happened between Earth and Venus at some point, the rocks from Earth may have contained microbial life that could have adapted to Venus’s highly acidic clouds (similar to Earth’s acid-resistant bacteria).</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/358784/original/file-20200918-16-7blw0k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Rendered image of meteorite hitting Earth." src="https://images.theconversation.com/files/358784/original/file-20200918-16-7blw0k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/358784/original/file-20200918-16-7blw0k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=384&fit=crop&dpr=1 600w, https://images.theconversation.com/files/358784/original/file-20200918-16-7blw0k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=384&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/358784/original/file-20200918-16-7blw0k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=384&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/358784/original/file-20200918-16-7blw0k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=483&fit=crop&dpr=1 754w, https://images.theconversation.com/files/358784/original/file-20200918-16-7blw0k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=483&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/358784/original/file-20200918-16-7blw0k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=483&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">If rocks from Earth containing microbial life entered Venus’s orbit in the past, this life may have adapted to Venus’s atmospheric conditions.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>A truly alien explanation</h2>
<p>The third explanation to consider is that a truly alien form of life (life as we <em>don’t</em> know it) could have formed on Venus’s 400°C surface and survives there to this day. </p>
<p>Such a foreign life probably wouldn’t be carbon-based, as nearly all complex carbon molecules break down at extreme temperatures. </p>
<p>Although carbon-based life produces phosphine on Earth, it’s impossible to say <em>only</em> carbon-based life can produce phosphine. Therefore, even if totally alien life exists on Venus, it may produce molecules that are still recognisable as a potential sign of life. </p>
<p>It’s only through further missions and research that we can find out whether there is, or was, life on Venus. As prominent scientist Carl Sagan <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3114207/#:%7E:text=non%2Dlocal%20perception-,Introduction,et%20al.%2C%201999">once said</a>: “extraordinary claims require extraordinary evidence”. </p>
<p>Luckily, two of the <a href="https://www.nasa.gov/press-release/nasa-selects-four-possible-missions-to-study-the-secrets-of-the-solar-system">four finalist proposals</a> for NASA’s next round of funding for planetary exploration are focused on Venus.</p>
<p>These include VERITAS, an orbiter proposed to map the surface of Venus, and DAVINCI+, proposed to drop through the planet’s skies and sample different atmospheric layers on the way down.</p><img src="https://counter.theconversation.com/content/146407/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Luke Steller receives funding from a Research Training Program scholarship provided by the Australian government. </span></em></p><p class="fine-print"><em><span>Martin Van Kranendonk receives funding from the Australian Research Council and BHP. </span></em></p>Considering what we know about the key ingredients for life’s formation on Earth, here are three explanations for how this process may have occurred on our sister planet.Luke Steller, PhD Student, UNSW SydneyMartin Van Kranendonk, Professor and Head of School, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1382052020-05-12T19:47:10Z2020-05-12T19:47:10ZExperts solve the mystery of a giant X-shaped galaxy, with a monster black hole as its engine<p>A team of US and South African researchers has <a href="https://arxiv.org/abs/2005.02723">published</a> highly detailed images of the largest X-shaped “radio galaxy” ever discovered – PKS 2014-55.</p>
<p>Notably, they’ve helped resolve ongoing confusion about the galaxy’s unusual shape.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/334265/original/file-20200512-175224-f1dbkn.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/334265/original/file-20200512-175224-f1dbkn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/334265/original/file-20200512-175224-f1dbkn.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=732&fit=crop&dpr=1 600w, https://images.theconversation.com/files/334265/original/file-20200512-175224-f1dbkn.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=732&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/334265/original/file-20200512-175224-f1dbkn.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=732&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/334265/original/file-20200512-175224-f1dbkn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=920&fit=crop&dpr=1 754w, https://images.theconversation.com/files/334265/original/file-20200512-175224-f1dbkn.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=920&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/334265/original/file-20200512-175224-f1dbkn.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=920&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The MeerKAT image of the giant X-shaped radio galaxy PKS 2014-55.</span>
<span class="attribution"><span class="source">Courtesy of SARAO and Bill Cotton et al/Author provided (no reuse)</span></span>
</figcaption>
</figure>
<p>The <a href="https://www.sarao.ac.za/media-releases/south-africas-meerkat-solves-mystery-of-x-galaxies/">spectacular new images</a> were taken using the 64-antenna <a href="https://www.sarao.ac.za/science-engineering/meerkat/about-meerkat/">MeerKAT</a> telescope in South Africa, by an international research team led by Bill Cotton of the US National Radio Astronomy Observatory. </p>
<h2>Zooming in on a cosmic giant</h2>
<p>Our research team also took detailed images of galaxy PKS 2014-55 last year, as part of the <a href="https://en.wikipedia.org/wiki/Evolutionary_Map_of_the_Universe">Evolutionary Map of the Universe project</a> led
by astrophysicist <a href="https://www.atnf.csiro.au/people/Ray.Norris/">Ray Norris</a>. We used CSIRO’s <a href="https://www.csiro.au/en/Research/Astronomy/ASKAP-and-the-Square-Kilometre-Array/SKA">Australian Square Kilometre Array Pathfinder</a> (ASKAP) telescope in Western Australia, which just completed its first set of pilot astronomical surveys. </p>
<p>Thanks to its innovative “radio cameras”, ASKAP can rapidly map very large areas of the sky to catalogue millions of objects emitting radio waves, from nearby supernova remnants to distant galaxies.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/334287/original/file-20200512-175219-s8xxo0.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/334287/original/file-20200512-175219-s8xxo0.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=782&fit=crop&dpr=1 600w, https://images.theconversation.com/files/334287/original/file-20200512-175219-s8xxo0.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=782&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/334287/original/file-20200512-175219-s8xxo0.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=782&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/334287/original/file-20200512-175219-s8xxo0.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=983&fit=crop&dpr=1 754w, https://images.theconversation.com/files/334287/original/file-20200512-175219-s8xxo0.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=983&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/334287/original/file-20200512-175219-s8xxo0.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=983&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Our ASKAP image of the giant X-shaped radio galaxy PKS 2014-55.</span>
<span class="attribution"><span class="source">CSIRO and the EMU team/Author provided (no reuse).</span></span>
</figcaption>
</figure>
<p>The prominent X-shape of PKS 2014-55 is made up of two pairs of <a href="https://blog.galaxyzoo.org/2014/02/03/the-curious-lives-of-radio-galaxies-part-one/">giant lobes</a> consisting of hot jets of electrons. These jets spurt outwards from a <a href="https://astronomy.swin.edu.au/cosmos/S/Supermassive+Black+Hole">supermassive black hole</a> at the galaxy’s heart.</p>
<p>The lobes emit electromagnetic radiation in the form of radio waves, which can only be detected by radio telescopes like <a href="https://www.csiro.au/en/Research/Facilities/ATNF/ASKAP">ASKAP</a>. Humans can’t see radio waves. But if we could, from Earth PKS 2014-55 would look about the same size as the Moon.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-the-universe-looks-like-when-viewed-with-radio-eyes-66381">What the universe looks like when viewed with radio eyes</a>
</strong>
</em>
</p>
<hr>
<h2>What makes a radio galaxy?</h2>
<p>Typically, <a href="https://en.wikipedia.org/wiki/Radio_galaxy">radio galaxies</a> have only one pair of lobes. One is a “jet” and the other a “counter-jet”. </p>
<p>These jets expand into the surrounding space at nearly the speed of light. They initially move in a straight line, but twist and bend into many marvellous shapes as they encounter their surroundings. </p>
<p>Centaurus A, seen below, is an example of a giant elliptical galaxy with two prominent radio lobes. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/334245/original/file-20200512-66657-3w0228.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/334245/original/file-20200512-66657-3w0228.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/334245/original/file-20200512-66657-3w0228.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=375&fit=crop&dpr=1 600w, https://images.theconversation.com/files/334245/original/file-20200512-66657-3w0228.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=375&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/334245/original/file-20200512-66657-3w0228.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=375&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/334245/original/file-20200512-66657-3w0228.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=471&fit=crop&dpr=1 754w, https://images.theconversation.com/files/334245/original/file-20200512-66657-3w0228.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=471&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/334245/original/file-20200512-66657-3w0228.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=471&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This is an artist’s impression of the famous Centaurus A galaxy, which has two prominent radio lobes emerging from its central black hole.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/gsfc/18199018792/in/photolist-tJbJf5-2dNEVuC-29htjhd-EEHmKy-rzqGTD-95Yds7-VWRqoY-9KgqiH-qLsNuo-2hREZpf-2i9UMm7-U7eWMd-2h9dNaZ-2hcZa9a-2gGzwWB-2g2YXPm-26Twqde-2iyBv3a-D2Jexx-2dYDFz5-HbrkoD-2iKYoeb-2ecFGiW-S9bNa5-2hn6G22-2i2DXQD-2icZgrT-2f7Tk25-YW3jMi-dyhNrD-tv7Viw-2ioaJLK-2cPDMFH-2iw39Y4-Nf1txG-wTUY9C-2hmvcEb-25jHWii-2hSYj8B-dxh7au-2iRWf2C-2iw2z2v-YW3DJX-PNyWWK-fue4yp-6JLH7w-2hUxAFv-7Hb1Zt-6Zfmp7-9KgqhX">NASA Goddard Space Flight Center/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Galaxy PKS 2014-55’s <a href="https://blog.galaxyzoo.org/2014/02/04/the-curious-lives-of-radio-galaxies-part-two/">giant X-shape</a>, with two pairs of lobes emerging at very different angles, is highly unusual. </p>
<h2>What makes the lobes?</h2>
<p>To understand why having two pairs of lobes is unusual, we first need to understand what creates the lobes.</p>
<p>Nearly all big galaxies have a supermassive black hole at their centre. </p>
<p>In an active galaxy, powerful jets of charged particles can emerge from the area around the supermassive black hole. Astronomers believe these are emitted from near the poles of the black hole, which is why there are two of them, and they usually point in opposite directions.</p>
<p>When the black hole’s activity stops, the jets stop growing and the material in them flows back towards the centre. Thus, what we see as one lobe of a radio galaxy is made up of both a jet spurting out, and the backflow material.</p>
<h2>A mystery solved</h2>
<p>In the past, there were two major theories for why PKS 2014-55 has two pairs of lobes. </p>
<p>The first suggested there were actually <em>two</em> massive active black holes at the galaxy’s centre, each emitting two <a href="https://blog.galaxyzoo.org/2014/01/22/how-do-black-holes-form-jets/">powerful jets</a>. </p>
<p>The second theory suggested the supermassive black hole had undergone a <a href="https://en.wikipedia.org/wiki/Spin-flip">spin flip</a>. This is when a rotating black hole’s spin axis has a sudden change in orientation, resulting in a second pair of jets at a different angle from the first pair.</p>
<p>But the recent observations from the South African MeerKAT telescope strongly suggest a third possibility: that the two larger lobes are the fast-moving particles zooming out from the black hole, while the two smaller lobes are the backflow looping around to fall back in.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/334263/original/file-20200512-175262-bogw1y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/334263/original/file-20200512-175262-bogw1y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/334263/original/file-20200512-175262-bogw1y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=335&fit=crop&dpr=1 600w, https://images.theconversation.com/files/334263/original/file-20200512-175262-bogw1y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=335&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/334263/original/file-20200512-175262-bogw1y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=335&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/334263/original/file-20200512-175262-bogw1y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=420&fit=crop&dpr=1 754w, https://images.theconversation.com/files/334263/original/file-20200512-175262-bogw1y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=420&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/334263/original/file-20200512-175262-bogw1y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=420&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The South African Radio Astronomy Observatory’s MeerKAT telescope array consists of 64 radio dishes (pictured). Computers combine signals from these antennas to synthesise a telescope eight kilometres in diameter.</span>
<span class="attribution"><span class="source">SARAO/Author provided (no reuse)</span></span>
</figcaption>
</figure>
<p>The MeerKAT team achieved high-resolution images ten times more sensitive than our ASKAP pilot observations conducted here in Australia last year. </p>
<h2>A cosmic wonder</h2>
<p>Using <a href="https://www.csiro.au/en/Research/Facilities/ATNF/ASKAP">CSIRO’s ASKAP</a> telescope, our team observed the “purple butterfly” of PKS 2014-55 to be an enormous cosmic structure. It spans at least five million light years – about 20 times the size of our own Milky Way galaxy. </p>
<p>PKS 2014-55 is located on the outskirts of a massive cluster of galaxies known as Abell 3667. It was discovered more than 60 years ago using the <a href="https://www.atnf.csiro.au/news/newsletter/jun02/Flowering_of_Fleurs.htm">Mills Cross Telescope</a> at CSIRO’s old <a href="https://www.environment.nsw.gov.au/heritageapp/ViewHeritageItemDetails.aspx?id=2260832">Fleurs field station</a> in New South Wales. </p>
<p>The galaxy was first seen by <a href="https://www.atnf.csiro.au/people/rekers/">Ron Ekers</a> using the <a href="https://www.cambridge.org/core/journals/publications-of-the-astronomical-society-of-australia/article/parkes-interferometer/9EB4F096050C7F3A8020E3770444C1E7">Parkes Interferometer</a> in 1969.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-brain-transplant-for-one-of-australias-top-telescopes-129138">A brain transplant for one of Australia's top telescopes</a>
</strong>
</em>
</p>
<hr>
<h2>ASKAP</h2>
<p>The ASKAP telescope we used to capture PKS 2014-55 is an array of 36 radio dishes laid out in a pattern six kilometres in diameter. Together, the dishes make up a large radio telescope that uses Earth’s rotation to produce sharp images of astronomical sources near and far. </p>
<p>Each dish is 12m wide and <a href="https://www.csiro.au/en/Research/Astronomy/ASKAP-and-the-Square-Kilometre-Array/PAFs">equipped</a> with new technologies developed by CSIRO and industry partners. ASKAP is a fast survey machine, taking radio images over very wide areas of the sky. Several surveys of the entire sky are expected to start next year.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/333671/original/file-20200508-49546-110hle4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/333671/original/file-20200508-49546-110hle4.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=298&fit=crop&dpr=1 600w, https://images.theconversation.com/files/333671/original/file-20200508-49546-110hle4.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=298&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/333671/original/file-20200508-49546-110hle4.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=298&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/333671/original/file-20200508-49546-110hle4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=375&fit=crop&dpr=1 754w, https://images.theconversation.com/files/333671/original/file-20200508-49546-110hle4.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=375&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/333671/original/file-20200508-49546-110hle4.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=375&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Australian Square Kilometre Array (ASKAP) radio telescope, located in the Murchison Shire in Western Australia.</span>
</figcaption>
</figure>
<hr>
<p><em>We acknowledge the Wajarri Yamatji as the traditional owners of the Murchison Radio-astronomy Observatory site.</em></p><img src="https://counter.theconversation.com/content/138205/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Baerbel Koribalski does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Like a cosmic butterfly in the sky, radio galaxy PKS 2014-55 was observed by CSIRO researchers with the Australian SKA Pathfinder telescope.Baerbel Koribalski, Senior research scientist, CSIROLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1200712019-07-10T20:18:57Z2019-07-10T20:18:57ZSpace Oddity at 50: the ‘novelty song’ that became a cultural touchstone<figure><img src="https://images.theconversation.com/files/283217/original/file-20190709-51258-1t3ofue.png?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">David Bowie in the film clip for Space Oddity: the song would become an anthem for space exploration with an enduring appeal.</span> <span class="attribution"><span class="source">YouTube</span></span></figcaption></figure><p>When the 22-year-old David Bowie penned Space Oddity, a song that would ultimately become a <a href="https://bowiesongs.wordpress.com/2009/11/11/space-oddity/">recognised</a> classic, he was a burgeoning pop artist without a record deal. A folk singer without a gig, a sometime mime, and a purveyor of <a href="https://youtu.be/NUiboPRPOzo">ice creams</a>. His first serious relationship, with the actress <a href="https://www.theguardian.com/commentisfree/2019/feb/01/david-bowie-girl-mousy-hair-muse">Hermione Farthingale</a>, was in free fall. </p>
<p>It was December 1968, and Bowie’s manager Kenneth Pitt was collating a promotional film to pimp his client’s wares to London television and film producers. He requested Bowie pen a “special piece of new material” to contemporise the otherwise retrospective nature of the film. </p>
<p>And then, on Christmas Eve, astronaut Bill Anders captured his iconic photograph of Earth from the Apollo 8 spacecraft while circumnavigating the Moon.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/283205/original/file-20190709-51262-1brzz2s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/283205/original/file-20190709-51262-1brzz2s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/283205/original/file-20190709-51262-1brzz2s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=480&fit=crop&dpr=1 600w, https://images.theconversation.com/files/283205/original/file-20190709-51262-1brzz2s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=480&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/283205/original/file-20190709-51262-1brzz2s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=480&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/283205/original/file-20190709-51262-1brzz2s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=603&fit=crop&dpr=1 754w, https://images.theconversation.com/files/283205/original/file-20190709-51262-1brzz2s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=603&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/283205/original/file-20190709-51262-1brzz2s.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">Earthrise, December 25, 1968</span>
<span class="attribution"><span class="source">NASA</span></span>
</figcaption>
</figure>
<p>The Earthrise image was still resonating in the public’s imagination when Bowie retreated to his room in Clareville Grove, London to write his space cabaret. Composing on a 12-string Hagstrom guitar with a little sonic weirdness from a Stylophone given to him by <a href="https://en.wikipedia.org/wiki/Marc_Bolan">Marc Bolan</a>, he came up with Space Oddity.</p>
<p>A blatant commercial object, a “pragmatic” turn by a fledgling artist, the song would become an anthem for space exploration for decades (and for TV news obituaries on the occasion of Bowie’s <a href="https://youtu.be/mH3-HV2WDdQ">death</a> in 2016). </p>
<p>Space Oddity tells of an astronaut Major Tom, launched into space in a manner akin to the Apollo missions. Yet in this instance all does not go according to plan and he is left adrift in the abyss of space, “floating ‘round my tin can, far above the Moon.”</p>
<p>At the time it was considered a “novelty song” to hang alongside other opportunists riding the vapor trails of the <a href="https://www.nasa.gov/audience/forstudents/5-8/features/nasa-knows/what-was-the-saturn-v-58.html">Saturn V</a>. (<a href="https://www.nytimes.com/2019/06/29/fashion/watches-omega-speedmaster-moonwatch-anniversary.html">Omega</a> watches, <a href="https://www.orlandosentinel.com/space/apollo-11-anniversary/os-ne-apollo-11-tang-20190704-ahrgsi5hmfdunfy4ldazrgvkr4-story.html">Tang</a>, <a href="https://www.atlasobscura.com/articles/first-energy-bar">Space Food Sticks</a> etc). Bowie was acutely aware of the commercialisation of the space exploration story, of course. “You have really made the grade, and the papers want to know whose shirts you wear,” exalts ground control as Tom hurtles towards the heavens.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/iYYRH4apXDo?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>Eschewing the typical pop song template, Bowie designed the piece as if it was a dramatic play. “I think I wanted to write a new kind of musical,” he <a href="https://slate.com/culture/2015/12/david-bowie-and-enda-walsh-musical-lazarus-reviewed.html">reflected</a> in 2002, “and that’s how I saw my future at the time.”</p>
<p>The song – one of his earliest and perhaps most outrageous musical assemblages – is also indicative of the artist he would become, a restless creative magpie perched by the wireless, plucking phrases and vocal stylings from the inbound radio waves. </p>
<p>The definitive version, recorded in late June 1969 at Trident Studios, was pressed and released as a single within three weeks – on July 11 – to leverage the hype of the impending Apollo moon landing. It also sealed a new recording deal with Mercury Records. Bowie was back.</p>
<p>However, his long-time producing partner <a href="https://en.wikipedia.org/wiki/Tony_Visconti">Tony Visconti</a> refused to work on the song, citing it as a distasteful departure from the singer’s hippie folk leanings. Visconti’s unease led him to recommend <a href="https://en.wikipedia.org/wiki/Gus_Dudgeon">Gus Dudgeon</a> (who would later work with Elton John) as producer. The song’s adventurous orchestration and unsettling harmonics owe much to Dudgeon’s ambition.</p>
<p>Through resonance, tone and unexpected harmonic shifts Bowie and Dudgeon achieved a meta-pop song full of cultural and musical references. There are lyrical and tonal references to the Bee Gees’ <a href="https://youtu.be/S43YhQ_eGTw">New York Mining Disaster 1941</a> while an acoustic passage signposts <a href="https://youtu.be/gP3-TU6xPvc">Old Friends</a> by Simon & Garfunkel. Even the metallic chimes of the Stylophone recall the pulsating intro of the Beatles’ <a href="https://youtu.be/t1Jm5epJr10">I Am The Walrus</a>. This was music for space, both inside and out, an experimental sonic palette that would open up a whole <a href="https://www.technologyreview.com/s/613762/space-music-drugs/">new genre</a> of musical art direction. </p>
<p>Of course, Kubrick’s <a href="https://www.imdb.com/title/tt0062622/">2001: A Space Odyssey</a> hangs heavily over proceedings. The two works are not only linked by name, but by their respective critiques of the cultural zeitgeist of “space fever”. </p>
<figure>
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<p>A sense of melancholia and detachment permeates Bowie’s recording. Yet, Major Tom’s predicament – floating in a tin can far above the world – is perhaps not the perilous event we might suspect. He seems quite OK with it all. Even his observation that there is “nothing I can do” comes across as somewhat of a relief.</p>
<p>We are never really sure whether the communication breakdown with ground control was accidental or by design. In Norman Mailer’s Apollo 11 chronicle <a href="https://www.goodreads.com/book/show/238970.Of_a_Fire_on_the_Moon">Of a Fire on the Moon</a>, he notes that the “obvious pleasure” of the astronaut, “was to be alone in the sky”.</p>
<h2>Rushing towards the stars</h2>
<p>Still, in a 1980 <a href="https://www.npr.org/sections/therecord/2017/10/06/555850186/how-ashes-to-ashes-put-the-first-act-of-david-bowies-career-to-rest">interview</a>, Bowie revealed Major Tom’s dilemma was a comment on what he saw at the time as the limits of American exceptionalism: </p>
<blockquote>
<p>Here we had the great blast of American technological know-how shoving this guy up into space, but once he gets there, he’s not quite sure why he’s there. And that’s where I left him.</p>
</blockquote>
<p>For such a challenging work, the press reaction in Britain to Space Oddity was largely positive, Tony Palmer, writing in the Observer, appreciated the song’s cynical air at a time when “we cling pathetically to every moonman’s dribbling joke, when we admire unquestioningly the so-called achievement of our helmeted heroes.” </p>
<p>Music journalist Penny Valentine’s review for the ensuing album, which would feature Space Oddity as the lead track, observed that Bowie had captured “the rather frightening atmosphere we all live in as the backdrop to his songs.”</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/283248/original/file-20190709-44505-1fqa54u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/283248/original/file-20190709-44505-1fqa54u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/283248/original/file-20190709-44505-1fqa54u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=288&fit=crop&dpr=1 600w, https://images.theconversation.com/files/283248/original/file-20190709-44505-1fqa54u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=288&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/283248/original/file-20190709-44505-1fqa54u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=288&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/283248/original/file-20190709-44505-1fqa54u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=362&fit=crop&dpr=1 754w, https://images.theconversation.com/files/283248/original/file-20190709-44505-1fqa54u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=362&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/283248/original/file-20190709-44505-1fqa54u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=362&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Cover of Space Oddity, the album.</span>
<span class="attribution"><span class="source">Author provided</span></span>
</figcaption>
</figure>
<p>Indeed, come July 1969, the promise of the Sixties and the hippy trip of the free love movement were a few festivals and a bunch of ghoulish murders away from coming to an end. The sense of being adrift like Major Tom was not just a fantasy construction any more. </p>
<p>The song’s television debut would be on July 20 when the BBC aired the track during the Apollo broadcast, albeit after the Lunar Module had safely touched down. A scenario that even surprised Bowie – “of course, I was overjoyed that they did”.</p>
<p>Despite its contrived beginnings, Bowie designed a cultural touchstone for a historic moment of human engineering and blind courage. Even 50 years hence, he appears to us fully formed on Space Oddity as a moonstruck balladeer and completely in sync with the times.</p>
<p>The immaculately dressed changeling who would go on to hit the glam rock jackpot with his alien stage persona <a href="https://youtu.be/3qrOvBuWJ-c">Ziggy Stardust</a>. A character who captured the abrasive temperament of the moment as he straddled the jet-trails of our collective rushing towards the stars.</p><img src="https://counter.theconversation.com/content/120071/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mitch Goodwin does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Fifty years ago, on July 11, 1969, David Bowie released Space Oddity. With its adventurous orchestration, unsettling harmonics and melancholy narrative, the now classic song captured a moment.Mitch Goodwin, Faculty of Arts, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.