tag:theconversation.com,2011:/ca/topics/aurora-australis-15735/articlesAurora Australis – The Conversation2023-03-29T04:32:17Ztag:theconversation.com,2011:article/2026182023-03-29T04:32:17Z2023-03-29T04:32:17ZWhat are auroras, and why do they come in different shapes and colours? Two experts explain<figure><img src="https://images.theconversation.com/files/518083/original/file-20230329-24-p4501h.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3000%2C1998&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://unsplash.com/photos/LtnPejWDSAY">Lightscape / Unsplash</a></span></figcaption></figure><p>Over millennia, humans have observed and been inspired by beautiful displays of light bands dancing across dark night skies. Today, we call these lights the aurora: the aurora borealis in the northern hemisphere, and the aurora australis in the south.</p>
<p>Nowadays, we understand auroras are caused by charged particles from Earth’s magnetosphere and the solar wind colliding with other particles in Earth’s upper atmosphere. Those collisions excite the atmospheric particles, which then release light as they “relax” back to their unexcited state. </p>
<p>The colour of the light corresponds to the release of discrete chunks of energy by the atmospheric particles, and is also an indicator of how much energy was absorbed in the initial collision.</p>
<p>The frequency and intensity of auroral displays is related to activity on the Sun, which follows an 11-year cycle. Currently, we are approaching the next maximum, which is <a href="https://www.weather.gov/news/201509-solar-cycle">expected in 2025</a>.</p>
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<figcaption><span class="caption">Fox Fires, a short film inspired by the Finnish folk tale of the aurora borealis.</span></figcaption>
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<h2>Connections to the Sun</h2>
<p>Such displays have long been documented by peoples throughout <a href="http://www.ewebtribe.com/NACulture/articles/aurora.html">North America</a>, Europe, <a href="https://www.smithsonianmag.com/smart-news/evidence-of-earliest-candidate-aurora-found-in-ancient-chinese-texts-180979979/">Asia</a> and <a href="https://education.riaus.org.au/cosmos-magazine-aurora-traditions-of-the-first-australians/">Australia</a>.</p>
<p>In the 17th century, scientific explanations for what caused the aurora began to surface. Possible explanations included air from Earth’s atmosphere rising out of Earth’s shadow to become sunlit (<a href="https://www.nasa.gov/mission_pages/themis/auroras/aurora_history.html">Galileo in 1619</a>) and light reflections from high-altitude ice crystals (<a href="https://pwg.gsfc.nasa.gov/polar/EPO/auroral_poster/aurora_all.pdf">Rene Descartes and others</a>). </p>
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Read more:
<a href="https://theconversation.com/do-the-northern-lights-make-sounds-that-you-can-hear-168032">Do the northern lights make sounds that you can hear?</a>
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<p>In 1716, English astronomer Edmund Halley was the first to suggest a possible connection with Earth’s magnetic field. In 1731, a French philosopher named Jean-Jacques d'Ortous de Mairan noted a coincidence between the number of <a href="https://theconversation.com/giant-sunspot-returns-and-its-bigger-and-badder-than-ever-34002">sunspots</a> and aurora. He proposed that the aurora was connected with the Sun’s atmosphere. </p>
<p>It was here that the connection between activity on the Sun was linked with auroras here on Earth, giving rise to the areas of science now called “<a href="https://www.nasa.gov/mission_pages/sunearth/the-heliopedia">heliophysics</a>” and “<a href="https://spaceplace.nasa.gov/spaceweather/en/">space weather</a>”.</p>
<h2>Earth’s magnetic field as a particle trap</h2>
<p>The most common source of <a href="https://media.bom.gov.au/social/blog/1557/what-is-an-aurora/#:%7E:text=The%20colour%20emitted%20depends%20on,dark%20red%20or%20blue%20light.">aurora</a> is particles travelling within Earth’s <a href="https://www.nasa.gov/mission_pages/sunearth/multimedia/magnetosphere.html">magnetosphere</a>, the region of space occupied by Earth’s natural magnetic field. </p>
<p>Images of Earth’s magnetosphere typically show how the magnetic field “bubble” protects Earth from space radiation and repels most disturbances in the solar wind. However, what is not normally highlighted is the fact that Earth’s magnetic field contains its own population of electrically charged particles (or “plasma”). </p>
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<figcaption><span class="caption">Model representation of Earth’s magnetic field interacting with the solar wind.</span></figcaption>
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<p>The magnetosphere is composed of charged particles that have escaped from Earth’s upper atmosphere and charged particles that have entered from the solar wind. Both types of particles are trapped in Earth’s magnetic field.</p>
<p>The motions of electrically charged particles are controlled by electric and magnetic fields. Charged particles gyrate around magnetic field lines, so when viewed at large scales magnetic field lines act as “pipelines” for charged particles in a plasma.</p>
<p>The Earth’s magnetic field is similar to a standard “dipole” magnetic field, with field lines bunching together near the poles. This bunching up of field lines actually alters the particle trajectories, effectively turning them around to go back the way they came, in a process called “magnetic mirroring”.</p>
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<figcaption><span class="caption">‘Magnetic mirroring’ makes charged particles bounce back and forth between the poles.</span></figcaption>
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<h2>Earth’s magnetosphere in a turbulent solar wind</h2>
<p>During quiet and stable conditions, most particles in the magnetosphere stay trapped, happily bouncing between the south and north magnetic poles out in space. However, if a disturbance in the solar wind (such as a <a href="https://www.swpc.noaa.gov/phenomena/coronal-mass-ejections">coronal mass ejection</a>) gives the magnetosphere a “whack”, it becomes disturbed. </p>
<p>The trapped particles are accelerated and the magnetic field “pipelines” suddenly change. Particles that were happily bouncing between north and south now have their bouncing location moved to lower altitudes, where Earth’s atmosphere becomes more dense.</p>
<p>As a result, the charged particles are now likely to collide with atmospheric particles as they reach the polar regions. This is called “particle precipitation”. Then, when each collision occurs, energy is transferred to the atmospheric particles, exciting them. Once they relax, they emit the light that forms the beautiful aurora we see.</p>
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<h2>Curtains, colours and cameras</h2>
<p>The amazing displays of aurora dancing across the sky are the result of the complex interactions between the <a href="https://www.nasa.gov/feature/goddard/2021/themis-researchers-find-standing-waves-at-edge-of-earth-magnetic-bubble">solar wind and the magnetosphere</a>. </p>
<p>Aurora appearing, disappearing, brightening and forming structures like curtains, swirls, picket fences and travelling waves are all visual representations of the invisible, ever-changing dynamics in Earth’s magnetosphere as it interacts with the solar wind.</p>
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<p>As these videos show, aurora comes in all sorts of <a href="https://aurorasaurus.org/learn#aurora-colors">colours</a>. </p>
<p>The most common are the greens and reds, which are both emitted by oxygen in the upper atmosphere. Green auroras correspond to altitudes close to 100 km, whereas the red auroras are higher up, above 200 km. </p>
<p>Blue colours are emitted by nitrogen – which can also emit some reds. A range of pinks, purples and even white light are also possible due to a mixture of these emissions.</p>
<p>The aurora is more brilliant in photographs because camera sensors are more sensitive than the human eye. Specifically, our eyes are less sensitive to colour at night. However, if the aurora is bright enough it can be quite a sight for the naked eye. </p>
<h2>Where and when?</h2>
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<figcaption><span class="caption">Catching aurora in the southern hemisphere.</span></figcaption>
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<p>Even under quiet space weather conditions, aurora can be very prominent at high latitudes, such as in <a href="https://allsky.gi.alaska.edu/">Alaska</a>, <a href="https://auroramax.com/live">Canada</a>, <a href="https://site.uit.no/spaceweather/data-and-products/tgo-all-sky-cameras/">Scandinavia</a> and <a href="http://polaris.nipr.ac.jp/%7Eacaurora/syoCDC/index.html">Antarctica</a>. When a space weather disturbance takes place, auroras can migrate to much lower latitudes to become visible across the continental <a href="https://www.youtube.com/watch?v=_Myo-0CLrck&t=2s">United States</a>, <a href="https://www.agenzianova.com/en/news/aurora-boreale-in-germania-video/">central Europe</a> and even <a href="https://twitter.com/Rosiebscorpio/status/1639180442053283840?s=20">southern</a> and <a href="https://twitter.com/perthobs/status/1639122431532216325?s=20">mainland Australia</a>. </p>
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<p>The severity of the space weather event typically controls the range of locations where the aurora is visible. The strongest events are the most rare.</p>
<p>So, if you’re interested in hunting auroras, keep an eye on your local space weather forecasts (<a href="https://www.swpc.noaa.gov/">US</a>, <a href="https://www.sws.bom.gov.au/">Australia</a>, <a href="https://www.metoffice.gov.uk/weather/specialist-forecasts/space-weather">UK</a>, <a href="https://spaceweather.sansa.org.za/">South Africa</a> and <a href="https://swe.ssa.esa.int/current-space-weather">Europe</a>). There are also numerous space weather experts on social media and even aurora-hunting citizen science projects (such as <a href="https://www.aurorasaurus.org/">Aurorasaurus</a>) that you can contribute towards!</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/uRufGWOiWmI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A rare sighting of the aurora australis from central Australia, with Uluru in the foreground.</span></figcaption>
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<p>Get outside and witness one of nature’s true natural beauties – aurora, Earth’s gateway to the heavens.</p>
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Read more:
<a href="https://theconversation.com/fire-in-the-sky-the-southern-lights-in-indigenous-oral-traditions-39113">Fire in the sky: The southern lights in Indigenous oral traditions</a>
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<img src="https://counter.theconversation.com/content/202618/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Brett Carter receives funding from the Australian Research Council, the SmartSat CRC and the Australian Department of Defence. He has also consulted for Chimu Adventures as part of their Southern Lights Flight tours. </span></em></p><p class="fine-print"><em><span>Elizabeth A. MacDonald receives funding from NASA and employed by NASA's Goddard Space Flight Center. The Aurorasaurus project receives funding from NASA and NSF. </span></em></p>The aurora is one of nature’s most spectacular sights, a dazzling glow in the upper atmosphere driven by space weather.Brett Carter, Associate Professor, RMIT UniversityElizabeth A. MacDonald, Space Physicist, NASALicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1878362022-08-01T20:03:39Z2022-08-01T20:03:39ZMeteors seem to be raining down on New Zealand, but why are some bright green?<figure><img src="https://images.theconversation.com/files/476788/original/file-20220731-19335-76trxr.jpg?ixlib=rb-1.1.0&rect=5%2C304%2C3828%2C1851&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Greg Price</span>, <span class="license">Author provided</span></span></figcaption></figure><p>New Zealand may seem to be under meteor bombardment at the moment. After a <a href="https://theconversation.com/equivalent-to-1-800-tonnes-of-tnt-what-we-now-know-about-the-meteor-that-lit-up-the-daytime-sky-above-new-zealand-186636">huge meteor exploded</a> above the sea near Wellington on July 7, creating a sonic boom that could be heard across the bottom of the South Island, a smaller fireball was captured two weeks later above Canterbury. </p>
<p><a href="https://fireballs.nz/">Fireballs Aotearoa</a>, a collaboration between astronomers and citizen scientists which aims to recover freshly fallen meteorites, has received a lot of questions about these events. One of the most frequent is about the bright green colour, and whether it is the same green produced by auroras. </p>
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<img alt="An image of an aurora australis" src="https://images.theconversation.com/files/476789/original/file-20220731-20-zrewrz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/476789/original/file-20220731-20-zrewrz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/476789/original/file-20220731-20-zrewrz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/476789/original/file-20220731-20-zrewrz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/476789/original/file-20220731-20-zrewrz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/476789/original/file-20220731-20-zrewrz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/476789/original/file-20220731-20-zrewrz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">An aurora australis observed from the international space station.</span>
<span class="attribution"><span class="source">Wikimedia Commons</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p>Green fireballs have been reported and filmed in New Zealand regularly. Bright meteors often signal the arrival of a chunk of asteroid, which can be anywhere between a few centimetres to a metre in diameter when it comes crashing through the atmosphere. </p>
<p>Some of these asteroids contain nickel and iron and they hit the atmosphere at speeds of up to 60km per second. This releases an enormous amount of heat very quickly, and the vapourised iron and nickel radiate green light. </p>
<p>But is this the same as the bright green of an aurora? For the most recent meteor, the answer is mainly no, but it’s actually not that simple.</p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/equivalent-to-1-800-tonnes-of-tnt-what-we-now-know-about-the-meteor-that-lit-up-the-daytime-sky-above-new-zealand-186636">Equivalent to 1,800 tonnes of TNT: what we now know about the meteor that lit up the daytime sky above New Zealand</a>
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<h2>The colours of a meteor trail</h2>
<p>The green glow of the aurora is caused by oxygen ions in the upper atmosphere, created by collisions between atmospheric oxygen molecules and particles ejected by the sun. </p>
<p>These oxygen ions recombine with electrons to produce oxygen atoms, but the electrons can persist in an excited state for several seconds. In an energy transition known as “forbidden” because it does not obey the usual quantum rules, they then radiate the auroral green light at 557nm wavelength.</p>
<p>A meteor can also shine by this route, but only if it’s extremely fast. Very fast meteors heat up in the thin atmosphere above 100km where auroras form. </p>
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Read more:
<a href="https://theconversation.com/are-the-northern-lights-caused-by-particles-from-the-sun-not-exactly-174019">Are the northern lights caused by 'particles from the Sun'? Not exactly</a>
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<p>If you want to see a green auroral wake from a meteor, watch out for the Perseid meteor shower, which has now started and will peak on August 13 in the southern hemisphere. </p>
<p>Also arriving at about 60km per second, the Perseids are extremely fast bits of the <a href="https://www.space.com/33677-comet-swift-tuttle-perseid-meteor-shower-source.html">comet Swift-Tuttle</a>. Some Perseids trail a beautiful, glowing and distinctly green wake behind them, particularly at the start of their path.</p>
<p>Once the Canterbury meteor hit on July 22, the capricious winds of the upper atmosphere twisted the gently glowing trail, resulting in a pale yellow glow towards the end (as seen in the GIF below, also recorded by Greg Price for an earlier meteor). This is caused by sodium atoms being continually excited in a catalytic reaction involving ozone.</p>
<p><img src="https://cdn.theconversation.com/static_files/files/2231/The_22_July_meteor_-_persistent_train_-_credit_Greg_Price.gif?1659310010" width="100%"> </p>
<h2>Are we being bombarded by meteors?</h2>
<p>Yes and no. The arrival of big, booming green meteors and the dropping of meteorites isn’t rare in New Zealand, but it is rare to recover the rock. Fireballs Aotearoa is working to improve the recovery rate.</p>
<p>In an average year, perhaps four meteorites hit New Zealand. We’re encouraging citizen scientists to build their own meteor camera systems so they can catch these events. </p>
<p>By comparing the meteor against the starry background and triangulating images caught by multiple cameras, we can pin down the meteor’s position in the atmosphere to within tens of metres.</p>
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<img alt="The July 22 meteor as seen by a specialised meteor camera near Ashburton." src="https://images.theconversation.com/files/476790/original/file-20220731-43929-h2dp31.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/476790/original/file-20220731-43929-h2dp31.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/476790/original/file-20220731-43929-h2dp31.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/476790/original/file-20220731-43929-h2dp31.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/476790/original/file-20220731-43929-h2dp31.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/476790/original/file-20220731-43929-h2dp31.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/476790/original/file-20220731-43929-h2dp31.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">
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<span class="caption">The July 22 meteor as seen by a specialised meteor camera near Ashburton.</span>
<span class="attribution"><span class="source">Campbell Duncan/NASA/CAMS NZ</span>, <span class="license">Author provided</span></span>
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<p>Not only does that help us find the rock, but it tells us what the pre-impact orbit of the meteoroid was, which in turn tells us which part of the solar system it came from. This is a rather efficient way of sampling the solar system without ever having to launch a space mission.</p>
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<img alt="Map of witness reports and cameras." src="https://images.theconversation.com/files/476791/original/file-20220731-31484-7i4x0t.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/476791/original/file-20220731-31484-7i4x0t.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=440&fit=crop&dpr=1 600w, https://images.theconversation.com/files/476791/original/file-20220731-31484-7i4x0t.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=440&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/476791/original/file-20220731-31484-7i4x0t.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=440&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/476791/original/file-20220731-31484-7i4x0t.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=553&fit=crop&dpr=1 754w, https://images.theconversation.com/files/476791/original/file-20220731-31484-7i4x0t.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=553&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/476791/original/file-20220731-31484-7i4x0t.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=553&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Witness reports and high-resolution meteor cameras help to calculate a meteor’s trajectory. This map shows the approximate trajectory of the July 22 meteor at the top of the red shape in the centre.</span>
<span class="attribution"><span class="source">Fireballs Aotearoa and International Meteor Association</span>, <span class="license">Author provided</span></span>
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<p>Fireballs Aotearoa is rapidly populating Otago with meteor cameras and there are half a dozen more in other parts of the South Island. The North Island isn’t well covered yet, and we’re keen for more people (in either island) to build or buy a meteor camera and keep it pointed at the sky. </p>
<p>Then next time a bright meteor explodes with a boom above New Zealand, we may be able to pick up the meteorite and do some good science with it.</p>
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<p><em>Many thanks for the input from Jim Rowe of the UK Fireball Alliance, and Greg Price who photographed the July 22 meteor and the persistent train.</em></p><img src="https://counter.theconversation.com/content/187836/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>William Jack Baggaley receives funding from University of Canterbury. </span></em></p>The green glow of an aurora is caused by oxygen ions in the upper atmosphere. Some meteors can glow in this way, too, but only if they are extremely fast.Jack Baggaley, Professor Emeritus Physics and Astronomy, University of CanterburyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1740192022-01-20T15:17:36Z2022-01-20T15:17:36ZAre the northern lights caused by ‘particles from the Sun’? Not exactly<figure><img src="https://images.theconversation.com/files/440264/original/file-20220111-23-19p1ssc.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5406%2C3599&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/northern-lights-on-night-sky-aurora-1908662476">PhotoVisions/Shutterstock</a></span></figcaption></figure><p>What a spectacle a big aurora is, its shimmering curtains and colourful rays of light illuminating a dark sky. Many people refer to aurora as the northern lights (the aurora borealis), but there are <a href="https://www.nationalgeographic.co.uk/travel/2020/05/electric-dreams-where-to-see-the-southern-lights">southern lights</a> too (the aurora australis). Either way, if you’re lucky enough to catch a glimpse of this phenomenon, it’s something you won’t soon forget.</p>
<p>The aurora is <a href="https://link.springer.com/article/10.1007%2Fs11214-021-00798-8">often explained simply</a> as “particles from the Sun” hitting our atmosphere. But that’s not technically accurate except in a few limited cases. So <a href="https://www.skyatnightmagazine.com/space-science/what-causes-northern-lights/">what does happen</a> to create this <a href="https://www.nasa.gov/aurora">natural marvel</a>?</p>
<p>We see the aurora when energetic charged particles – electrons and sometimes ions – collide with atoms in the upper atmosphere. While the aurora often follows explosive events on the Sun, it’s not quite true to say these energetic particles that cause the aurora come from the Sun.</p>
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Read more:
<a href="https://theconversation.com/curious-kids-what-causes-the-northern-lights-111573">Curious Kids: what causes the northern lights?</a>
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</p>
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<p>Earth’s magnetism, the force that directs the compass needle, dominates the motions of electrically charged particles in space around Earth. The <a href="https://www.feynmanlectures.caltech.edu/II_01.html#Ch1-S2">magnetic field</a> near the surface of Earth is normally steady, but its strength and direction fluctuate when there are displays of the aurora. These fluctuations are caused by what’s called a magnetic substorm – a rapid disturbance in the magnetic field in near-Earth space.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/440886/original/file-20220114-23-1o904tp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/440886/original/file-20220114-23-1o904tp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=365&fit=crop&dpr=1 600w, https://images.theconversation.com/files/440886/original/file-20220114-23-1o904tp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=365&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/440886/original/file-20220114-23-1o904tp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=365&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/440886/original/file-20220114-23-1o904tp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=459&fit=crop&dpr=1 754w, https://images.theconversation.com/files/440886/original/file-20220114-23-1o904tp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=459&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/440886/original/file-20220114-23-1o904tp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=459&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Many people travel to high-latitude countries every year in the hope of seeing the northern lights.</span>
<span class="attribution"><span class="source">Douglas Cooper</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>To understand what happens to trigger a substorm, we first need to learn about plasma. Plasma is a gas in which a significant number of the atoms have been broken into ions and electrons. The gas of the uppermost regions of Earth’s atmosphere is in the plasma state, as is the gas that makes up the Sun and other stars. A gas of plasma flows away continuously from the Sun: this is called the <a href="https://www.jpl.nasa.gov/nmp/st5/SCIENCE/solarwind.html">solar wind</a>.</p>
<p>Plasma behaves differently from those gases we meet in everyday life. Wave a magnet around in your kitchen and nothing much happens. The air of the kitchen consists overwhelmingly of electrically neutral atoms, so it’s quite undisturbed by the moving magnet. In a plasma, however, with its electrically charged particles, things are different. So if your house was filled with plasma, waving a magnet around would make the air move.</p>
<p>When solar wind plasma arrives at the earth it interacts with the planet’s magnetic field (as illustrated below – the magnetic field is represented by the lines that look a bit like a spider). Most of the time, plasma travels easily along the lines of the magnetic field, but not across them. This means that solar wind arriving at Earth is diverted around the planet and kept away from the Earth’s atmosphere. In turn, the solar wind drags the field lines out into the elongated form seen on the night side, called the magnetotail.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/440887/original/file-20220114-27-1lpyj1p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/440887/original/file-20220114-27-1lpyj1p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=469&fit=crop&dpr=1 600w, https://images.theconversation.com/files/440887/original/file-20220114-27-1lpyj1p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=469&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/440887/original/file-20220114-27-1lpyj1p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=469&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/440887/original/file-20220114-27-1lpyj1p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=589&fit=crop&dpr=1 754w, https://images.theconversation.com/files/440887/original/file-20220114-27-1lpyj1p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=589&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/440887/original/file-20220114-27-1lpyj1p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=589&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A coronal mass ejection leaves the Sun, travelling towards the Earth’s magnetic field (this image is not to scale).</span>
<span class="attribution"><a class="source" href="https://sohowww.nascom.nasa.gov/gallery/images/large/sunearth01_prev.jpg">SOHO (ESA & NASA)</a></span>
</figcaption>
</figure>
<p>Sometimes moving plasma brings magnetic fields from different regions together, causing a local breakdown in the pattern of magnetic field lines. This phenomenon, called <a href="https://www.nasa.gov/content/goddard/science-of-magnetic-reconnection">magnetic reconnection</a>, heralds a new magnetic configuration, and, importantly, unleashes a huge amount of energy. </p>
<p>These events happen fairly often in the Sun’s outer atmosphere, causing an explosive energy release and pushing clouds of magnetised gas, called coronal mass ejections, away from the Sun (as seen in the image above).</p>
<p>If a coronal mass ejection arrives at Earth it can in turn trigger reconnection in the magnetotail, releasing energy that drives electrical currents in near-Earth space: the substorm. Strong <a href="https://link.springer.com/article/10.1007%2Fs11214-008-9373-9">electric fields</a> that develop in this process accelerate electrons to high energies. Some of these electrons may have come from the solar wind, allowed into near-Earth space by reconnection, but their acceleration in the substorm is essential to their role in the aurora.</p>
<p>These particles are then funnelled by the magnetic field towards the atmosphere high above the polar regions. There they collide with the oxygen and nitrogen atoms, exciting them <a href="http://wp.lancs.ac.uk/aurorawatchuk/2017/05/10/the-vivid-lights-what-causes-the-colour-of-the-aurora/">to glow</a> as the aurora.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/northern-lights-to-death-rays-how-electromagnetism-haunts-our-everyday-life-85129">Northern lights to death rays: how electromagnetism haunts our everyday life</a>
</strong>
</em>
</p>
<hr>
<p>Now you know exactly what causes the northern lights, how do you optimise your chances of seeing it? Seek out dark skies far from cities and towns. The further north you can go the better but you don’t need to be in the Arctic Circle. We see them from time to time in Scotland, and they’ve even been spotted in the <a href="https://www.bbc.co.uk/news/uk-england-tyne-59929434">north of England</a> – although they’re still better seen at higher latitudes.</p>
<p>Websites such as <a href="https://aurorawatch.lancs.ac.uk/">AuroraWatch UK</a> can tell you when it’s worth heading outside. And remember that while <a href="http://sidc.oma.be/">events on the Sun</a> can give us a few days warning, these are indicative, not foolproof. Perhaps part of the magic lies in the fact that you need a little bit of luck to see the aurora in all its glory.</p><img src="https://counter.theconversation.com/content/174019/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alexander MacKinnon has previously received funding from the STFC, for research on energetic phenomena on the Sun.</span></em></p>It’s often said that the aurora, or the northern lights, is caused by ‘particles from the Sun’. But in reality things are more complicated.Alexander MacKinnon, Honorary Research Fellow, Physics and Astronomy, University of GlasgowLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1650002021-10-21T19:12:08Z2021-10-21T19:12:08ZCurious Kids: Why are the northern lights only spotted near the North Pole?<figure><img src="https://images.theconversation.com/files/427864/original/file-20211021-15-1x7qi1g.jpg?ixlib=rb-1.1.0&rect=0%2C12%2C8075%2C2864&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Aurora Australis, or Southern Lights, reflected in the water.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><em>Curious Kids is a series for children of all ages. Have a question you’d like an expert to answer? Send it to <a href="mailto:curiouskidscanada@theconversation.com">CuriousKidsCanada@theconversation.com</a>.</em></p>
<blockquote>
<p><strong>Why are the northern lights only spotted at areas around the poles? — Naba, 9, Oakville, Ont.</strong></p>
</blockquote>
<p>The northern lights are also called auroras, and they are regularly visible near Earth’s North and South Poles. They are a direct connection between the Earth and what’s happening on the sun.</p>
<p>Did you know that the sun has weather? But unlike Earth’s weather, the sun’s weather can affect the entire solar system! We call it space weather.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/solar-weather-has-real-material-effects-on-earth-118453">Solar weather has real, material effects on Earth</a>
</strong>
</em>
</p>
<hr>
<p>The sun is constantly blowing a spray of tiny particles in all directions, called the solar wind. This wind isn’t made of air, like on Earth. It’s made of mostly hydrogen, and it’s blowing at hundreds of kilometres per second (this is more than a thousand times faster than hurricane-force wind on Earth). </p>
<p>This incredibly fast wind has been blowing on to the Earth for billions of years, so why hasn’t it blown away Earth’s air by crashing into us?</p>
<p>Fortunately, for living things like us, the Earth has a magnetic field, which causes the planet to act like a giant magnet in space and protects Earth from the solar wind. Earth’s magnetic field is what causes <a href="https://www.livescience.com/32732-how-does-a-compass-work.html">a compass to work</a>. <a href="https://www.steampoweredfamily.com/activities/how-to-make-a-compass/">The small magnet in a compass</a> aligns with Earth’s magnetic field and always points to Earth’s magnetic North Pole. Earth’s magnetic field is totally invisible to our eyes, but we can <a href="https://www.geomag.nrcan.gc.ca/mag_fld/default-en.php">measure it with magnets and other scientific instruments</a>.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/o4FSg-90XlA?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A NASA video showing how the Earth’s magnetic field protects from the solar wind.</span></figcaption>
</figure>
<p>The particles that make up the solar wind are deflected by Earth’s magnetic field, so they mostly pass around the Earth without crashing into us. But it’s not a perfect shield: because of the <a href="https://science.nasa.gov/science-news/news-articles/earths-magnetosphere">shape of Earth’s magnetic field</a>, close to the North and South Poles, a little bit of the solar wind can sometimes get through and crash directly into the Earth’s atmosphere.</p>
<p>This crash happens between very tiny particles at speeds much faster than a bullet, so the result is very different from than say, a car crash. Instead of throwing off smaller pieces or exploding, they emit light. The colours tell us about what type of atmospheric particle is being crashed into by the solar wind. Red and green are from oxygen collisions, and blue is from nitrogen.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/427892/original/file-20211021-24-1b9lal4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="the northern lights" src="https://images.theconversation.com/files/427892/original/file-20211021-24-1b9lal4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/427892/original/file-20211021-24-1b9lal4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/427892/original/file-20211021-24-1b9lal4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/427892/original/file-20211021-24-1b9lal4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/427892/original/file-20211021-24-1b9lal4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/427892/original/file-20211021-24-1b9lal4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/427892/original/file-20211021-24-1b9lal4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=499&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 northern lights as seen from Iceland.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<h2>Space weather</h2>
<p>Exactly what the auroras look like depends a bit on the state of Earth’s magnetic field and atmosphere, but more directly depends on space weather. Sometimes the sun produces a storm, called a <a href="https://www.swpc.noaa.gov/phenomena/solar-flares-radio-blackouts">solar flare</a> or a <a href="https://earthsky.org/space/what-are-coronal-mass-ejections/">coronal mass ejection</a>, when there are suddenly a lot more particles injected into the solar wind, making it stronger than usual. Because we have telescopes <a href="https://sohowww.nascom.nasa.gov/">in space</a> and <a href="http://obs.astro.ucla.edu/intro.html">on Earth</a> that carefully watch the sun for these storms, we usually have two to three days warning before a storm hits the Earth.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/space-weather-is-difficult-to-predict-with-only-an-hour-to-prevent-disasters-on-earth-159895">Space weather is difficult to predict — with only an hour to prevent disasters on Earth</a>
</strong>
</em>
</p>
<hr>
<p>Typically, a solar storm will cause an impressive display of auroras only for people who live in the far north and south of the world, underneath the part of Earth’s magnetic field that can let the solar wind through. But sometimes, a really powerful storm can cause the auroras to be visible much closer to the equator. </p>
<p>When this happens, it means that a lot of the solar wind particles are crashing all over Earth’s atmosphere. It’s not dangerous to us directly because we’re protected from these fast-moving particles by Earth’s atmosphere. But astronauts who are above the atmosphere may have <a href="https://www.space.com/3247-astronauts-sleep-safety-solar-flare.html">to take shelter in a heavily shielded part of the space station</a>, and satellites can be temporarily shut down or even broken.</p>
<p>On very rare occasions, the auroras caused by a solar storm can be so powerful that <a href="https://www.nasa.gov/topics/earth/features/sun_darkness.html">electrical lines</a> on Earth can be damaged, causing many people to <a href="https://www.washingtonpost.com/news/capital-weather-gang/wp/2013/10/31/the-scary-halloween-solar-storm-of-2003-a-warning-for-todays-space-weather/">lose power</a>.</p>
<p>The sun has a cycle of storms: <a href="https://spaceplace.nasa.gov/solar-cycles/">it has more frequent storms every 11 years</a>, which is called the solar maximum. When the sun is near solar maximum, auroras are more likely to happen. The next solar maximum is <a href="https://www.nasa.gov/press-release/solar-cycle-25-is-here-nasa-noaa-scientists-explain-what-that-means">predicted to be in late 2024 or early 2025</a>, so we will have more and more auroras to watch over the next few years.</p>
<p>If you want to see auroras, you can check the <a href="https://spaceweather.com/">space weather forecast</a> every night just like you can check your local weather forecast every day.</p>
<p>In places close to the poles, where people have been watching auroras for as long as we’ve been human, <a href="https://newsinteractives.cbc.ca/longform/legends-of-the-northern-lights">many cultures understand the lights as a cosmic connection</a>. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/fire-in-the-sky-the-southern-lights-in-indigenous-oral-traditions-39113">Fire in the sky: The southern lights in Indigenous oral traditions</a>
</strong>
</em>
</p>
<hr>
<p>A truly bright auroral display is an incredible experience. It’s a powerful reminder of connection between the Earth’s atmosphere, magnetic field and the sun, all of which are vitally important to life on Earth. </p>
<hr>
<p><em>Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to <a href="mailto:curiouskidscanada@theconversation.com">CuriousKidsCanada@theconversation.com</a>. Please tell us your name, age and the city where you live.</em>
<em>And since curiosity has no age limit — adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.</em></p>
<hr><img src="https://counter.theconversation.com/content/165000/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Samantha Lawler receives funding from the Natural Sciences and Engineering Research Council of Canada.</span></em></p>A curious kid asks: Why are the northern lights only spotted at areas around the poles?Samantha Lawler, Assistant professor of astronomy, University of ReginaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1554452021-03-23T02:53:31Z2021-03-23T02:53:31ZClimate explained: how particles ejected from the Sun affect Earth’s climate<figure><img src="https://images.theconversation.com/files/386315/original/file-20210224-17-sbtks2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Earth's magnetic field protects us from the solar wind, guiding the solar particles to the polar regions.</span> <span class="attribution"><a class="source" href="https://sohowww.nascom.nasa.gov/gallery/images/sunearth01.html">SOHO (ESA & NASA)</a></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/287622/original/file-20190811-144878-bvgm9l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/287622/original/file-20190811-144878-bvgm9l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/287622/original/file-20190811-144878-bvgm9l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/287622/original/file-20190811-144878-bvgm9l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/287622/original/file-20190811-144878-bvgm9l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/287622/original/file-20190811-144878-bvgm9l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/287622/original/file-20190811-144878-bvgm9l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
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<span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p><em><strong><a href="https://theconversation.com/nz/topics/climate-explained-74664">Climate Explained</a></strong> is a collaboration between The Conversation, Stuff and the New Zealand Science Media Centre to answer your questions about climate change.</em> </p>
<p><em>If you have a question you’d like an expert to answer, please send it to <a href="mailto:climate.change@stuff.co.nz">climate.change@stuff.co.nz</a></em></p>
<hr>
<blockquote>
<p><strong>When the Sun ejects solar particles into space, how does this affect the Earth and climate? Are clouds affected by these particles?</strong></p>
</blockquote>
<p>When we consider the Sun’s influence on Earth and our climate, we tend to think about solar radiation. We are acutely aware of the skin-burning dangers of ultraviolet, or UV, radiation. </p>
<p>But the Sun is an active star. It also continuously releases what is known as “<a href="https://en.wikipedia.org/wiki/Solar_wind">solar wind</a>”, made up of charged particles, largely protons and electrons, that travel at speeds of hundreds of kilometres per hour.</p>
<p>Some of these particles that reach Earth are guided into the polar atmosphere by our magnetic field. As a result, we can see the southern lights, aurora australis, in the southern hemisphere, and the northern equivalent, aurora borealis. </p>
<figure class="align-center ">
<img alt="Aurora Australis" src="https://images.theconversation.com/files/389700/original/file-20210315-21-hbzclj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/389700/original/file-20210315-21-hbzclj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=372&fit=crop&dpr=1 600w, https://images.theconversation.com/files/389700/original/file-20210315-21-hbzclj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=372&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/389700/original/file-20210315-21-hbzclj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=372&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/389700/original/file-20210315-21-hbzclj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=467&fit=crop&dpr=1 754w, https://images.theconversation.com/files/389700/original/file-20210315-21-hbzclj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=467&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/389700/original/file-20210315-21-hbzclj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=467&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Aurora australis observed above southern New Zealand.</span>
<span class="attribution"><span class="source">Shutterstock/Fotos593</span></span>
</figcaption>
</figure>
<p>This visible manifestation of solar particles entering Earth’s atmosphere is a constant reminder there is more to the Sun than sunlight. But the particles have other effects as well. </p>
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<strong>
Read more:
<a href="https://theconversation.com/why-is-the-suns-atmosphere-so-hot-spacecraft-starts-to-unravel-our-stars-mysteries-128242">Why is the sun's atmosphere so hot? Spacecraft starts to unravel our star's mysteries</a>
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<h2>Solar particles and ozone</h2>
<p>When solar particles enter the atmosphere, their high energies ionise neutral atmospheric nitrogen and oxygen molecules, which make up 99% of the atmosphere. This “<a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016GL068279">energetic particle precipitation</a>”, named because it’s like a rain of particles from space, is a major source of <a href="https://progearthplanetsci.springeropen.com/articles/10.1186/s40645-014-0024-3">ionisation in the polar atmosphere</a> above 30km altitude — and it sets off a chain of reactions that produces <a href="https://aura.gsfc.nasa.gov/science/feature-20200701.html">chemicals</a> that facilitate the <a href="https://www.nobelprize.org/prizes/chemistry/1995/crutzen/lecture/">destruction of ozone</a>. </p>
<p>The impact of solar particles on atmospheric ozone was first observed in 1969. Since the early 2000s, thanks to new kinds of satellite observations, we have seen growing evidence that solar particles play an <a href="https://www.nature.com/articles/ncomms6197">important part</a> in influencing polar ozone. During particularly active times, when the Sun releases large amounts of particles into space, up to 60% of ozone at altitudes above 50km can be depleted. The effect can last for weeks.</p>
<p>Lower down in the atmosphere, below 50km, solar particles are important contributors to the year-to-year variability in polar ozone levels, often through <a href="https://progearthplanetsci.springeropen.com/articles/10.1186/s40645-014-0024-3">indirect pathways</a>. Here, solar particles again contribute to <a href="https://ozonewatch.gsfc.nasa.gov/facts/">ozone loss</a>, but a recent discovery showed they also help curb some of the <a href="https://doi.org/10.5194/acp-21-2819-2021">depletion in the Antarctic ozone hole</a>.</p>
<h2>How ozone affects the climate</h2>
<p>Most of the ozone in the atmosphere resides in a thin layer at altitudes of 20-25km — the “<a href="https://scied.ucar.edu/learning-zone/atmosphere/ozone-layer">ozone layer</a>”. </p>
<p>But ozone is everywhere in the atmosphere, from the Earth’s surface to altitudes above 100km. It is a greenhouse gas and plays a key role in heating and cooling the atmosphere, which makes it critical for climate. </p>
<p>In the southern hemisphere, <a href="https://doi.org/10.1002/qj.2330">changes in polar ozone</a> are known to influence regional climate conditions. </p>
<figure class="align-center ">
<img alt="Satellite image of Earth's atmosphere" src="https://images.theconversation.com/files/389699/original/file-20210315-17-gr8nv2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/389699/original/file-20210315-17-gr8nv2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=364&fit=crop&dpr=1 600w, https://images.theconversation.com/files/389699/original/file-20210315-17-gr8nv2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=364&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/389699/original/file-20210315-17-gr8nv2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=364&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/389699/original/file-20210315-17-gr8nv2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=457&fit=crop&dpr=1 754w, https://images.theconversation.com/files/389699/original/file-20210315-17-gr8nv2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=457&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/389699/original/file-20210315-17-gr8nv2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=457&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Solar particles ionise nitrogen and oxygen molecules in the atmosphere, which leads to other chemical reactions that contribute to ozone destruction.</span>
<span class="attribution"><span class="source">Shutterstock/PunyaFamily</span></span>
</figcaption>
</figure>
<p>Its depletion above Antarctica had a cooling effect, which in turn pulled the westerly wind jet that circles the continent closer. As the Antarctic hole recovers, this <a href="https://www.uow.edu.au/media/2019/ozone-depletion-driving-climate-change-in-southern-hemisphere.php">wind belt can meander further north</a> and affect rainfall patterns, sea-surface temperatures and ocean currents. The <a href="https://niwa.co.nz/climate/information-and-resources/southern-annular-mode">Southern Annular Mode</a> describes this north-south movement of the wind belt that circles the southern polar region.</p>
<p>Ozone is important for future climate predictions, not only in the thin ozone layer, but throughout the atmosphere. It is crucial we understand the factors that influence ozone variability, be it man-made or natural like the Sun. </p>
<h2>The Sun’s direct influence</h2>
<p>The link between solar particles and ozone is reasonably well established, but what about any direct effects solar particles may have on the climate? </p>
<p>We have observational evidence that solar activity influences <a href="https://doi.org/10.1029/2008JA014029">regional climate variability at both poles</a>. Climate models also suggest such polar effects link to larger climate patterns (such as the Northern and Southern Annular Modes) and influence conditions in mid-latitudes. </p>
<p>The details are not yet well understood, but for the first time the influence of <a href="https://doi.org/10.5194/gmd-10-2247-2017">solar particles on the climate system</a> will be included in climate simulations used for the upcoming Intergovernmental Panel on Climate Change (<a href="https://www.ipcc.ch/">IPCC</a>) assessment.</p>
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Read more:
<a href="https://theconversation.com/solar-weather-has-real-material-effects-on-earth-118453">Solar weather has real, material effects on Earth</a>
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<p>Through solar radiation and particles, the Sun provides a key energy input to our climate system. While these do vary with the Sun’s 11-year cycle of magnetic activity, they can not explain the recent rapid increase in global temperatures due to climate change.</p>
<p>We know rising levels of <a href="https://www.acs.org/content/acs/en/climatescience/greenhousegases.html">greenhouse gases</a> in the atmosphere are pushing up Earth’s surface temperature (the physics have been known <a href="https://www.sciencedirect.com/science/article/pii/S0160932716300308">since the 1800s</a>). We also know human activities have greatly <a href="https://www.esrl.noaa.gov/gmd/ccgg/trends/">increased greenhouse gases</a> in the atmosphere. Together these two factors explain the observed rise in global temperatures.</p>
<h2>What about clouds?</h2>
<p>Clouds are much lower in the atmosphere than where most solar particles penetrate. Particles know as galactic cosmic rays (coming from the centre of our galaxy rather than the Sun) may be linked to cloud formation. </p>
<p>It has been suggested cosmic rays could influence the formation of condensation nuclei, which act as “seeds” for clouds. But recent <a href="https://doi.org/10.1002/2017JD027475">research</a> at the <a href="https://home.cern/">CERN</a> nuclear research facility suggests the effects are insignificant. </p>
<p>This doesn’t rule out some other mechanisms for cosmic rays to affect cloud formation, but thus far there is little supporting evidence.</p><img src="https://counter.theconversation.com/content/155445/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Annika Seppälä is a Senior Lecturer at the University of Otago. She has previously received research funding from the European Council and the Academy of Finland.</span></em></p>When solar particles reach the Earth, they not only produce spectacular auroras but also contribute to the chemical reactions leading to ozone depletion, which in turn influences climate patterns.Annika Seppälä, Senior Lecturer in Geophysics, University of OtagoLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1550402021-02-15T04:00:08Z2021-02-15T04:00:08ZWe found the first Australian evidence of a major shift in Earth’s magnetic poles. It may help us predict the next<figure><img src="https://images.theconversation.com/files/384156/original/file-20210215-21-1bbrzt.jpg?ixlib=rb-1.1.0&rect=20%2C37%2C2227%2C1085&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>About 41,000 years ago, something remarkable happened: Earth’s magnetic field flipped and, for a temporary period, magnetic north was south and magnetic south was north. </p>
<p><a href="https://www.nature.com/subjects/palaeomagnetism">Palaeomagnetists</a> refer to this as a geomagnetic excursion. This event, which is different to a complete magnetic pole reversal, occurs irregularly through time and reflects the dynamics of Earth’s molten <a href="https://www.nationalgeographic.org/encyclopedia/core/">outer core</a>. </p>
<p>The strength of Earth’s magnetic field would have almost vanished during the event, called the Laschamp excursion, which lasted a <a href="https://www.frontiersin.org/articles/10.3389/feart.2019.00086/full">few thousand years</a>. </p>
<p>Earth’s magnetic field acts as a shield against high-energy particles from the Sun and outside the solar system. Without it the planet would be bombarded by these charged particles. </p>
<p>We don’t know when the next geomagnetic excursion will happen. But if it happened today, it would be crippling. </p>
<p>Satellites and navigation apps would be rendered useless — and power distribution systems would be disrupted at a cost of <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016SW001491">between</a> US$7 billion and US$48 billion each day in the United States alone.</p>
<p>Obviously, satellites and electric grids didn’t exist 41,000 years ago. But the Laschamp excursion — named after the lava flows in France where it was first recognised — still left its mark. </p>
<p>We recently detected its signature in Australia for the first time, in a 5.5 metre-long sediment core taken from the bottom of Lake Selina, Tasmania. </p>
<p>Within these grains lay 270,000 years of history, which we unpack in <a href="https://www.sciencedirect.com/science/article/abs/pii/S1871101421000030">our paper</a> published in the journal Quaternary Geochronology. </p>
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Read more:
<a href="https://theconversation.com/explainer-what-happens-when-magnetic-north-and-true-north-align-123265">Explainer: what happens when magnetic north and true north align?</a>
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<h2>How sediment can record Earth’s magnetic field</h2>
<p>Rock and soil can naturally contain magnetic particles, such as the iron mineral <a href="https://www.sciencedirect.com/topics/engineering/magnetite">magnetite</a>. These magnetic particles are like tiny compass needles aligned with Earth’s magnetic field. </p>
<p>They can be carried from the landscape into lakes through rainfall and wind. They eventually accumulate on the lake’s bottom, becoming buried and locking in place. They effectively become a fossil record of Earth’s magnetic field. </p>
<p>Scientists can then drill into lake beds and use a device called a magnetometer to recover the information held by the lake sediment. The deeper we drill, the further back in time we go.</p>
<p>In 2014 my colleagues and I travelled to Lake Selina in Tasmania with the goal of extracting the area’s climate, vegetation and “paleomagnetic” record, which is the record of Earth’s magnetic field stored in rocks, sediment and other materials.</p>
<p>Led by University of Melbourne Associate Professor <a href="https://findanexpert.unimelb.edu.au/profile/6089-michael-shawn-fletcher">Michael-Shawn Fletcher</a>, we drilled into the lake floor from a makeshift floating platform rigged to two inflatable rafts.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/384153/original/file-20210215-15-1accaw6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Lake Selina, Tasmania." src="https://images.theconversation.com/files/384153/original/file-20210215-15-1accaw6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/384153/original/file-20210215-15-1accaw6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=425&fit=crop&dpr=1 600w, https://images.theconversation.com/files/384153/original/file-20210215-15-1accaw6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=425&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/384153/original/file-20210215-15-1accaw6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=425&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/384153/original/file-20210215-15-1accaw6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=533&fit=crop&dpr=1 754w, https://images.theconversation.com/files/384153/original/file-20210215-15-1accaw6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=533&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/384153/original/file-20210215-15-1accaw6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=533&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Lake Selina is a small sub-alpine lake located near the west coast of Tasmania. Sediment from the lake was sampled in the form of 2x2cm cubes, each containing a few hundred years’ worth of magnetic field history.</span>
<span class="attribution"><span class="source">Michael-Shawn Fletcher</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>The first Australian evidence of Laschamp</h2>
<p>Our dating of the core revealed that the biggest shift in magnetic pole positions and the lowest magnetic field intensity at Lake Selina both occurred during the Laschamp excursion.</p>
<p>But for a core that spanned several glacial periods, no single dating method could be trusted to precisely determine its age. So we employed numerous scientific techniques including radiocarbon dating and beryllium isotope <a href="https://www.cerege.fr/fr/equipements/ln2c">analysis</a>.</p>
<p>The latter involves tracking the presence of an isotope called beryllium-10. This is formed when high-energy cosmic particles bombard Earth, colliding with oxygen and nitrogen atoms in the atmosphere. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/new-evidence-for-a-human-magnetic-sense-that-lets-your-brain-detect-the-earths-magnetic-field-113536">New evidence for a human magnetic sense that lets your brain detect the Earth's magnetic field</a>
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</p>
<hr>
<p>Since a weaker magnetic field leads to more of these charged particles bombarding Earth, we expected to find more beryllium-10 in sediment containing magnetic particles “locked-in” during the Laschamp excursion. Our findings confirmed this.</p>
<p>The interaction between charged cosmic particles and air particles in Earth’s atmosphere is also what creates auroras. Several generations of people would have witnessed a plethora of spectacular auroras during the Laschamp excursion. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/384141/original/file-20210214-19-1q3v064.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Aurora borealis over the Gulf of Finland." src="https://images.theconversation.com/files/384141/original/file-20210214-19-1q3v064.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/384141/original/file-20210214-19-1q3v064.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/384141/original/file-20210214-19-1q3v064.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/384141/original/file-20210214-19-1q3v064.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/384141/original/file-20210214-19-1q3v064.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/384141/original/file-20210214-19-1q3v064.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/384141/original/file-20210214-19-1q3v064.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=499&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 interaction between charged cosmic particles and the highest air particles in Earth’s atmosphere is what creates auroras. During the Laschamp excursion, several generations of people would have witnessed a plethora of spectacular auroras.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Building on work from the 1980s</h2>
<p>Only two other lakes in Australia — Lake Barrine and Lake Eacham in Queensland — have provided a “full-vector” record, wherein both the <a href="https://academic.oup.com/gji/article/81/1/103/674602">past directions</a> and <a href="https://academic.oup.com/gji/article/81/1/121/674627">past intensity</a> of the magnetic field are obtained from the same core. </p>
<p>But at 14,000 years old, the records from these lakes are much younger than the Laschamp excursion. Four decades later, our work at Lake Selina with modern techniques has revealed the exciting potential for similar research at other Australian lakes. </p>
<p>Currently, Australia is considered a paleomagnetic “blind spot”. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/384170/original/file-20210215-23-1eo00yc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Stalactites hang from cave ceiling." src="https://images.theconversation.com/files/384170/original/file-20210215-23-1eo00yc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/384170/original/file-20210215-23-1eo00yc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/384170/original/file-20210215-23-1eo00yc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/384170/original/file-20210215-23-1eo00yc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/384170/original/file-20210215-23-1eo00yc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/384170/original/file-20210215-23-1eo00yc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/384170/original/file-20210215-23-1eo00yc.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">‘Speleothems’ such as stalactites (pictured) and stalagmites are mineral deposits that form in caves.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>More data from lake sediments, archaeological artefacts, lava flows and mineral <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/speleothem">cave formations</a>, including stalagmites and stalactites, could greatly improve our understanding of Earth’s magnetic field. </p>
<p>With this knowledge, we may one day potentially be able to predict the next geomagnetic excursion, before our phones stop working and the birds overhead veer off-course and crash into windows.</p>
<p>Our dating of the Lake Selina core is just the start. We’re sure there are more secrets embedded beneath, waiting to be found. And so we continue our search.</p>
<hr>
<p><em>This work was carried out in collaboration with <a href="http://www.archaeomagnetism.com/taal-lab-facilities">La Trobe University</a>, the <a href="http://rses.anu.edu.au/research/facilities/palaeomagnetic-laboratory">Australian National University</a>, The University of Wollongong, the Australian Nuclear Science and Technology Organisation and the European Centre for Research and Teaching in Environmental Geosciences (<a href="https://www.cerege.fr/fr/equipements/ln2c">CEREGE</a>).</em></p><img src="https://counter.theconversation.com/content/155040/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Agathe Lise-Pronovost receives funding from the Australian Research Council. </span></em></p>Researchers have found the first Australian evidence of this global event, during which people on Earth would have witnessed a multitude of spectacular auroras.Agathe Lise-Pronovost, McKenzie Research Fellow in Earth Sciences, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1115732019-02-12T12:33:10Z2019-02-12T12:33:10ZCurious Kids: what causes the northern lights?<figure><img src="https://images.theconversation.com/files/258503/original/file-20190212-174887-2wfoul.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4851%2C3224&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A magical sight. </span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/ronel_reyes/8479833336/sizes/l">Ronel Reyes/Flickr.</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p><em><a href="https://theconversation.com/au/topics/curious-kids-36782">Curious Kids</a> is a series by <a href="https://theconversation.com/uk">The Conversation</a>, which gives children of all ages the chance to have their questions about the world answered by experts. All questions are welcome: find out how to enter at the bottom of this article.</em> </p>
<hr>
<blockquote>
<p><strong>What causes the northern lights? – Ffion, age 6.75, Pembrokeshire, UK.</strong></p>
</blockquote>
<p>I first saw the <a href="https://theconversation.com/uk/topics/northern-lights-14791">northern lights</a> three years ago, while driving home one night. They were so beautiful, I had to stop the car and get out to have a proper look, even though it was cold. Although the northern lights might look like magic, they can actually be explained by science – with a bit of help from the Sun, birds and fizzy drinks. </p>
<p>The energy for making the northern lights comes from the Sun. The Sun creates something called the “solar wind”. This is different to the light that we get from the Sun, which keeps us warm and helps us to see during the day.</p>
<p>This solar wind drifts away from the Sun through space, carrying tiny particles called protons and electrons. Protons and electrons are some of the tiny building blocks that make up most of the stuff in the universe, like plants and chocolate and me and you.</p>
<p>Think of the smallest Lego bricks you have in your toy box, which can be stuck together to make bigger things - these are what protons and electrons (and neutrons too) are to the universe. These particles carry lots of energy from the Sun, on their journey through space.</p>
<h2>The solar wind</h2>
<p>Sometimes the solar wind is strong, and sometimes it’s weak. We can only see the northern lights at times when the solar wind is strong enough. </p>
<p>When the solar wind reaches planet Earth, something very interesting happens: it runs into the Earth’s magnetic field. The magnetic field forces the solar wind away, and makes it travel around the Earth instead.</p>
<p>The magnetic field is what makes the needle on a compass point north, and is how birds know where to go when they migrate – it’s also why we have the north and south poles at all. </p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/fVsONlc3OUY?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
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<p>The magnetic field interacts with the solar wind and guides the protons and electrons down towards Earth along the magnetic field, away from the middle of the planet and toward the north and south poles.</p>
<p>Because of this, we get both northern and <a href="https://theconversation.com/uk/topics/southern-lights-15736">southern lights</a> – also known as the <a href="https://theconversation.com/uk/topics/aurora-borealis-14790">aurora borealis</a> and the <a href="https://theconversation.com/uk/topics/aurora-australis-15735">aurora australis</a>. </p>
<h2>Shake it up</h2>
<p>When the solar wind gets past the magnetic field and travels towards the Earth, it runs into the atmosphere. The atmosphere is like a big blanket of gas surrounding our planet, which contains lots of different particles that make up the air that we breathe and help to protect us from harmful radiation from the Sun. </p>
<p>As the protons and electrons from the solar wind hit the particles in the Earth’s atmosphere, they release energy – and this is what causes the northern lights. </p>
<p>Here’s how it happens: imagine you have a bottle of fizzy drink, and you give it a good shake. This puts lots of energy into the bottle, and when you open it, this energy will be released in a big stream of fizzy bubbles. </p>
<p>In the same way, the protons and electrons from the Sun “shake up” the particles in the atmosphere. Then, the particles let out all that energy in the form of light (instead of bubbles). </p>
<p>Different types of particles in the atmosphere make different colours after they’re shaken up – oxygen makes red and green light, and nitrogen makes blue light. Our eyes see green best out of all the colours, so we see green the brightest when we look at the northern lights.</p>
<p>It is easiest to see the northern lights in winter when is it very dark at night, and also outside of cities and away from street lights. You are more likely to see them the further north you are too. Check out this great website <a href="https://aurorawatch.lancs.ac.uk/">Aurora Watch</a> from Lancaster University – it might just help you find them!</p>
<p><em>This article has been corrected: the Earth’s magnetic field is not weaker at the poles, as the article originally stated.</em></p>
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<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=376&fit=crop&dpr=1 600w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=376&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=376&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=472&fit=crop&dpr=1 754w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=472&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=472&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="attribution"><a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p><em>Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question – along with your name, age and town or city where you live – to curiouskids@theconversation.com. Send as many questions as you want! We won’t be able to answer every question, but we’ll do our best.</em></p>
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<p><em>More <a href="https://theconversation.com/topics/curious-kids-36782?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=CuriousKidsUK">Curious Kids</a> articles, written by academic experts:</em></p>
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<li><p><em><a href="https://theconversation.com/curious-kids-why-do-spiders-have-hairy-legs-108602?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=CuriousKidsUK">Why do spiders have hairy legs? - Audrey, age five, Melbourne, Australia</a></em></p></li>
<li><p><em><a href="https://theconversation.com/curious-kids-why-are-there-different-seasons-at-specific-times-of-the-year-109380?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=CuriousKidsUK">Why do we have different seasons at specific times of the year? – Shrey, age nine, Mumbai, India</a></em></p></li>
<li><p><em><a href="https://theconversation.com/curious-kids-how-is-water-made-109434?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=CuriousKidsUK">How is water made? – Clara, age eight, Canberra, Australia</a></em></p></li>
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<p class="fine-print"><em><span>Paul O'Mahoney does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The northern lights might look like magic, but they can actually be explained by science – here’s how.Paul O'Mahoney, Post-Doctoral Research Assistant in Photobiology, University of DundeeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/927112018-03-29T10:29:39Z2018-03-29T10:29:39ZSpace weather threatens high-tech life<figure><img src="https://images.theconversation.com/files/212007/original/file-20180326-159081-ibu4ks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A coronal mass ejection erupts from the sun in 2012.</span> <span class="attribution"><a class="source" href="https://svs.gsfc.nasa.gov/11095">NASA</a></span></figcaption></figure><p>Shortly after 4 a.m. on a crisp, cloudless September morning in 1859, the sky above what is currently Colorado erupted in bright red and green colors. Fooled by the brightness into <a href="https://arstechnica.com/science/2012/05/1859s-great-auroral-stormthe-week-the-sun-touched-the-earth/">thinking it was an early dawn</a>, gold-rush miners in the mountainous region of what was then called the Kansas Territory woke up and started making breakfast. What happened in more developed regions was even more disorienting, and carries a warning for the wired high-tech world of the 21st century.</p>
<p>As the sky lit up over the nighttime side of the Earth, <a href="https://io9.gizmodo.com/how-the-carrington-event-let-telegraphs-run-on-aurora-p-1686759750">telegraph systems worldwide went berserk</a>, clacking nonsense code and emitting large sparks that ignited fires in nearby piles of paper tape. Telegraph operators <a href="https://science.nasa.gov/science-news/science-at-nasa/2008/06may_carringtonflare">suffered electrical burns</a>. Even disconnecting the telegraph units from their power sources <a href="https://science.nasa.gov/science-news/science-at-nasa/2008/06may_carringtonflare">didn’t stop the frenzy</a>, because the transmission wires themselves were carrying huge electrical currents. Modern technology had just been humbled by a fierce space weather storm that had arrived from the sun, the <a href="http://doi.org/10.1029/2011SW000734">largest ever recorded</a> – and more than twice as powerful as a storm nine years earlier, which had itself been the largest in known history.</p>
<p>My seven years of research on predicting solar storms, combined with my decades using GPS satellite signals under <a href="http://www.cis.rit.edu/%7Errdpci/space-weather.html">various solar storm conditions</a>, indicate that today’s even more sensitive electronics and satellites would be devastated should an event of that magnitude occur again. In 2008, a panel of experts commissioned by the National Academy of Sciences issued a detailed report with a sobering conclusion: The world would be <a href="https://www.nap.edu/catalog/12643/severe-space-weather-events-understanding-societal-and-economic-impacts-a">thrown back to the life of the early 1800s</a>, and it would take years – or even a decade – to recover from an event that large. </p>
<h2>A solar explosion</h2>
<p>Space weather storms have happened since the birth of the solar system, and have <a href="https://arxiv.org/ftp/arxiv/papers/0902/0902.3446.pdf">hit Earth many times</a>, both before and after that massive event in 1859, which was named the <a href="https://arstechnica.com/science/2012/05/1859s-great-auroral-stormthe-week-the-sun-touched-the-earth/">Carrington event</a> after a British astronomer who <a href="http://www.solarstorms.org/SCarrington.html">recorded his observations of the sun</a> at the time. They’re caused by huge electromagnetic explosions on the surface of the sun, called <a href="https://www.swpc.noaa.gov/phenomena/coronal-mass-ejections">coronal mass ejections</a>. Each explosion sends billions of protons and electrons, in a <a href="http://pluto.space.swri.edu/image/glossary/plasma.html">superheated ball of plasma</a>, out into the solar system.</p>
<p><a href="https://spacemath.gsfc.nasa.gov/weekly/3Page27.pdf">About 1 in every 20</a> coronal mass ejections heads in a direction that <a href="https://theconversation.com/how-facebook-the-wal-mart-of-the-internet-dismantled-online-subcultures-71536">intersects Earth’s orbit</a>. <a href="https://www.spaceweatherlive.com/en/help/how-do-we-know-if-a-cme-is-earth-directed-and-when-its-going-to-arrive">Around three days later</a>, our planet experiences what is called a space weather storm or a geomagnetic storm. </p>
<p>While these events are described using terms like “weather” and “storm,” they do not affect whether it’s rainy or sunny, hot or cold, or other aspects of what it’s like outdoors on any given day. Their effects are not meteorological, but only electromagnetic. </p>
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<a href="https://images.theconversation.com/files/212010/original/file-20180326-159081-14mbyu0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/212010/original/file-20180326-159081-14mbyu0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/212010/original/file-20180326-159081-14mbyu0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/212010/original/file-20180326-159081-14mbyu0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/212010/original/file-20180326-159081-14mbyu0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/212010/original/file-20180326-159081-14mbyu0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/212010/original/file-20180326-159081-14mbyu0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/212010/original/file-20180326-159081-14mbyu0.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">Aurorae are signs of a geomagnetic storm.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/image-feature/goddard/2017/northern-lights-over-alaska-2">NASA/Terry Zaperach</a></span>
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<h2>Hitting Earth</h2>
<p>When the coronal mass ejection arrives at Earth, the charged particles collide with air molecules in the upper atmosphere, generating heat and <a href="https://www.timeanddate.com/astronomy/northern-southern-lights.html">light called aurora</a>.</p>
<p>Also, as happens anytime <a href="https://www.youtube.com/watch?v=DVcvKwEUYqk">moving electrical charges encounter a magnetic field</a>, the interaction creates a spontaneous electrical current in any conductor that’s available. If the plasma ball is big enough, its interaction with Earth’s magnetic field can induce <a href="https://doi.org/10.1002/swe.20065">large currents on long wires</a> on the ground, like the one that overloaded telegraph circuits in 1859.</p>
<p><iframe id="6KR2O" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/6KR2O/2/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>On March 13, 1989, a storm only about <a href="https://www.swpc.noaa.gov/noaa-scales-explanation">one-fifth as strong</a> as the Carrington event hit Earth. It induced a large surge of current in the long power lines of the <a href="http://www.hydroquebec.com/learning/notions-de-base/tempete-mars-1989.html">Hydro-Quebec power grid</a>, causing physical damage to transmission equipment and leaving <a href="https://www.scientificamerican.com/article/geomagnetic-storm-march-13-1989-extreme-space-weather/">6 million people without power for nine hours</a>. Another storm-induced power surge <a href="https://spectrum.ieee.org/energy/the-smarter-grid/a-perfect-storm-of-planetary-proportions">destroyed a large transformer</a> at a New Jersey nuclear plant. Even though a spare transformer was nearby, it still took <a href="http://www.solarstorms.org/SWChapter1.html">six months to remove and replace</a> the melted unit. Some people worried that the bright auroral lights meant <a href="https://www.washingtonpost.com/news/capital-weather-gang/wp/2017/06/08/trumps-budget-eliminates-program-that-detects-infrastructure-crippling-solar-storms/">nuclear war had broken out</a>.</p>
<p>And in October 2003, a rapid series of solar storms affected Earth. Collectively called the Halloween solar storm, this series <a href="https://www.nasa.gov/topics/solarsystem/features/halloween_storms.html">caused surges</a> that <a href="https://www.directionsmag.com/article/1510">threatened the North American power grid</a>. Its <a href="https://www.space.com/23396-scary-halloween-solar-storm-2003-anniversary.html">effects on satellites</a> made GPS navigation erratic and interrupted communications connections during the peak of the storm.</p>
<p>Larger storms will have wider effects, cause more damage and take longer to recover from.</p>
<h2>Wide-reaching effects</h2>
<p>Geomagnetic storms attack the lifeblood of modern technology: electricity. A space weather storm typically lasts for two or three days, during which the entire planet is subjected to powerful electromagnetic forces. The <a href="https://www.nap.edu/catalog/12643/severe-space-weather-events-understanding-societal-and-economic-impacts-a">National Academy of Sciences study</a> concluded that an especially massive storm would damage and shut down power grids and communications networks worldwide.</p>
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<figcaption>
<span class="caption">Electricity, shown in the upper right, is integrated into every aspect of modern life.</span>
<span class="attribution"><a class="source" href="https://www.fcc.gov/help/public-safety-tech-topic-19-communications-interdependencies">Federal Communications Commission</a></span>
</figcaption>
</figure>
<p>After the storm passed, there would be no simple way to restore power. Manufacturing plants that build replacements for burned-out lines or power transformers would have no electricity themselves. Trucks needed to deliver raw materials and finished equipment wouldn’t be able to fuel up, either: Gas pumps run on electricity. And what pumps were running would soon dry up, because electricity also runs the machinery that extracts oil from the ground and refines it into usable fuel. </p>
<p>With transportation stalled, food wouldn’t get from farms to stores. Even systems that seem non-technological, like public water supplies, would shut down: Their pumps and purification systems need electricity. People in developed countries would find themselves with no running water, no sewage systems, no refrigerated food, and no way to get any food or other necessities transported from far away. People in places with more basic economies would also be without needed supplies from afar.</p>
<p>It could take <a href="https://www.nap.edu/catalog/12643/severe-space-weather-events-understanding-societal-and-economic-impacts-a">between four and 10 years</a> to repair all the damage. In the meantime, people would need to grow their own food, find and carry and purify water, and cook meals over fires.</p>
<p>Some systems would continue to operate, of course: bicycles, horse-drawn carriages and sailing ships. But another type of equipment that would keep working provides a clue to preventing this type of disaster: Electric cars would continue to work, but only in places where there were solar panels and wind turbines to recharge them.</p>
<h2>Preparing and protecting</h2>
<p>Geomagnetic storms would affect those small-scale installations far less than grid-scale systems. It’s a basic principle of electricity and magnetism that the longer a wire that’s exposed to a moving magnetic field, the <a href="https://doi.org/10.1016/S1364-6826(02)00126-8">larger the current that’s induced</a> in that wire.</p>
<p>In 1859, the telegraph system was so profoundly affected because it had wires stretching from city to city across the U.S. Those very long wires had to handle enormous amounts of energy all at once, and failed. Today, there are long runs of wires connecting power generators to consumers – such as <a href="https://www.eia.gov/todayinenergy/detail.php?id=27152">from Niagara Falls to New York City</a> – that would be similarly susceptible to large induced currents.</p>
<p>The only way to reduce vulnerability to geomagnetic storms is to substantially revamp the power grid. Now, it is a <a href="https://www.eia.gov/todayinenergy/detail.php?id=27152">vast web of wires</a> that effectively spans continents. Governments, businesses and communities need to work together to split it into much smaller components, each serving a town or perhaps even a neighborhood – or an individual house. These “<a href="https://www.energy.gov/articles/how-microgrids-work">microgrids</a>” can be connected to each other, but should have <a href="https://science.nasa.gov/science-news/science-at-nasa/2010/26oct_solarshield">protections built in</a> to allow them to be disconnected quickly when a storm approaches. That way, the length of wires affected by the storm will be shorter, reducing the potential for damage.</p>
<p>A family using solar panels and batteries for storage and an electric car to get around would likely find its water supply, natural gas or internet service disrupted. But their freedom to travel, and to use electric lights to work after dark, would provide a much better chance at survival.</p>
<h2>When will the next storm hit?</h2>
<p>People should start preparing today. It’s impossible to know when a major storm will hit next: The most we’ll get is a <a href="https://theconversation.com/new-solar-storm-forecasting-technique-breaks-the-24-hour-warning-barrier-for-earth-42917">three-day warning</a> when something happens on the surface of the sun. It’s really only a matter of time before there is another one like the Carrington event.</p>
<p><a href="https://doi.org/10.1063/1.4993929">Solar astrophysicists</a> are also studying the sun to identify any events or conditions that might herald a coronal mass ejection. They’re collecting enormous amounts of data about the sun and using computer analysis to try to connect that information to geomagnetic storms on Earth. This work is underway and will become more refined over time. The research has not yet yielded a reliable prediction of a coming solar storm before an ejection occurs, but it improves each year. </p>
<p>In my view, the safest course of action involves developing microgrids based on renewable energy. That would not only improve people’s quality of life around the planet right now, but also provide the best opportunity to maintain that lifestyle when adverse events happen.</p><img src="https://counter.theconversation.com/content/92711/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Roger Dube has previously received funding from the National Aeronautics and Space Administration (NASA). </span></em></p>The wired Earth of the 21st century is at the mercy of the volatile nature of the sun.Roger Dube, Research Professor of Imaging Science, Rochester Institute of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/836772017-09-08T00:18:31Z2017-09-08T00:18:31ZMassive sunspots and huge solar flares mean unexpected space weather for Earth<figure><img src="https://images.theconversation.com/files/185178/original/file-20170907-9585-c1fei2.jpg?ixlib=rb-1.1.0&rect=183%2C0%2C1615%2C1074&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A huge solar flare flashes in the middle of the sun on Sept. 6, 2017. A separate image of the Earth provides scale.</span> <span class="attribution"><a class="source" href="https://svs.gsfc.nasa.gov/12706">NASA/GSFC/SDO</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>If you still have your solar viewing glasses from the eclipse, now is a good time to slap them on and look up at the sun. You’ll see two big dark areas visible on our star. These massive sunspots are regions of intense and complicated magnetic fields that can produce solar flares – bursts of high-energy radiation. You can just make them out with solar viewing glasses, but they’re better viewed through a solar telescope. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"905107565406818304"}"></div></p>
<p>These two huge sunspots are currently causing quite a bit of consternation and interest. The solar storms they’ve sent toward Earth may affect communications and other technologies like GPS and radio signals. They’re causing amazing displays of the Northern and Southern Lights. And space weather scientists like us are excited because we wouldn’t normally expect this much activity from the sun at the moment.</p>
<p>The sun goes through 11-year cycles of solar activity. What scientists call a solar maximum is the time in the cycle when the sun is putting out the most energy. That’s when we tend to see the most sunspots, solar flares and associated solar storms. Some solar maxima are larger or more active than others – such as the 1990-1991 solar max. But this last cycle, which peaked in 2014, was <a href="https://solarscience.msfc.nasa.gov/predict.shtml">quite small</a>, and there were few large geomagnetic storms.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/185117/original/file-20170907-9538-1uarzku.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/185117/original/file-20170907-9538-1uarzku.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/185117/original/file-20170907-9538-1uarzku.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/185117/original/file-20170907-9538-1uarzku.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/185117/original/file-20170907-9538-1uarzku.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/185117/original/file-20170907-9538-1uarzku.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/185117/original/file-20170907-9538-1uarzku.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/185117/original/file-20170907-9538-1uarzku.jpeg?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"></a>
<figcaption>
<span class="caption">The number of sunspots varies over the years, but you’d expect to see more during solar maxima and fewer during solar minima.</span>
<span class="attribution"><a class="source" href="http://www.swpc.noaa.gov/products/goes-x-ray-flux">NOAA</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>We’re heading into the bottom of solar minimum, when the sun tends to have fewer sunspots, <a href="https://www.nasa.gov/content/goddard/the-difference-between-flares-and-cmes">solar flares</a> and <a href="http://www.swpc.noaa.gov/phenomena/coronal-mass-ejections">coronal mass ejections</a> – large <a href="http://earthsky.org/space/what-are-coronal-mass-ejections">expulsions of plasma, electrons and ions, and magnetic fields</a>. But despite where we are in the sun’s cycle, activity on the sun has dramatically picked up over the past few days. On and off, these two sunspots have been flaring and shooting out coronal mass ejections, directed toward Earth.</p>
<p>So what’s going on with the sun? And should we be concerned about this somewhat out-of-character solar behavior?</p>
<h2>Here’s what’s happened so far</h2>
<p>On September 4, the sun started sputtering. A moderately large flare (<a href="https://www.nasa.gov/mission_pages/sunearth/news/classify-flares.html">classified as an M5.5</a>) erupted at approximately 18:30 UTC. It produced a coronal mass ejection aimed at Earth.</p>
<p>The sun continued to flare on September 5. A <a href="https://helios.gsfc.nasa.gov/sep.html">solar energetic particle</a> event from the previous day’s activity arrived at the Earth, where it likely affected radio communications as well as the health of satellite systems.</p>
<p>On September 6, the sun produced two massive <a href="https://www.nasa.gov/mission_pages/sunearth/news/X-class-flares.html">X-class flares</a>. This is the category for the strongest of all solar flares.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"905456884911661057"}"></div></p>
<p>NASA announced one was <a href="https://www.nasa.gov/feature/goddard/2017/active-region-on-sun-continues-to-emits-solar-flares">the most powerful since at least 2008</a>. It <a href="https://twitter.com/NASASun/status/905822026488619008">produced another coronal mass ejection</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/185122/original/file-20170907-9542-wyifki.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/185122/original/file-20170907-9542-wyifki.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/185122/original/file-20170907-9542-wyifki.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/185122/original/file-20170907-9542-wyifki.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/185122/original/file-20170907-9542-wyifki.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/185122/original/file-20170907-9542-wyifki.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/185122/original/file-20170907-9542-wyifki.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/185122/original/file-20170907-9542-wyifki.jpeg?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"></a>
<figcaption>
<span class="caption">The second and strongest of the two X-class flares on September 6 produced a coronal mass ejection directed at Earth.</span>
<span class="attribution"><span class="source">NOAA</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Over the next day, the same sunspots continued to spit out more solar flares. It took about an hour for the <a href="https://helios.gsfc.nasa.gov/sep.html">solar energetic particles</a> they emitted to arrive at Earth. These protons are incredibly fast-moving. They can affect communication systems, typically in the polar regions where they are more likely to enter into the Earth’s atmosphere. As with all increases of radiation in space, they can also affect satellite systems and the health of astronauts. </p>
<p>Early in the morning hours of September 7 in the U.S., that first coronal mass ejection that erupted from the sun three days earlier arrived at Earth. Because of the way its magnetic field aligned with Earth’s, it <a href="http://wdc.kugi.kyoto-u.ac.jp/dst_realtime/201709/index.html">generated only a small geomagnetic storm</a>.</p>
<p>After being detected by spacecraft upstream from Earth in the solar wind, the massive coronal mass ejection from September 6 also hit Earth on the evening of September 7 EDT. Its arrival was a few hours earlier than <a href="http://www.swpc.noaa.gov/products/wsa-enlil-solar-wind-prediction">space weather forecasting agencies</a> around the world predicted.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/185185/original/file-20170907-9603-8u5a2w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/185185/original/file-20170907-9603-8u5a2w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/185185/original/file-20170907-9603-8u5a2w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/185185/original/file-20170907-9603-8u5a2w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/185185/original/file-20170907-9603-8u5a2w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/185185/original/file-20170907-9603-8u5a2w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/185185/original/file-20170907-9603-8u5a2w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/185185/original/file-20170907-9603-8u5a2w.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">Both sunspots are visible on the sun’s surface, as well as the flare in the solar atmosphere.</span>
<span class="attribution"><a class="source" href="https://svs.gsfc.nasa.gov/12706">NASA/GSFC/SDO</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>What other effects will Earth see?</h2>
<p>All this solar activity has already caused a couple of radiation storms in Earth’s high latitude regions that <a href="http://www.swpc.noaa.gov/phenomena/solar-flares-radio-blackouts">blacked out radio communication</a> at certain frequencies. The impacts extended toward the equator and have affected high-frequency communications, including ham radios, which are used in emergency and disaster relief management. Radio fade-out maps from the <a href="http://www.sws.bom.gov.au/HF_Systems/6/2/2">Australian Bureau of Meteorology</a> show that <a href="http://www.swpc.noaa.gov/communities/radio-communications">high-frequency radio communication disruptions</a> have likely occurred in the same areas being pummeled by Hurricane Irma.</p>
<p>There has likely been a <a href="https://www.engadget.com/2017/09/07/a-huge-solar-flare-temporarily-knocked-out-gps-communications/">loss of global navigation system satellite communications</a> in those same areas, but it will take time for the data to be analyzed and for us to gain a full understanding of how this space weather activity has affected those on the ground. The <a href="https://theconversation.com/are-you-a-frequent-flyer-solar-storm-radiation-can-be-harmful-28775">radiation storms</a> may also force flights over the polar regions to reroute to avoid increased radiation exposures for people on board and potential loss of communication and navigation systems for aircraft on these paths. </p>
<p>With the collision of the coronal mass ejection from this X-class flare with Earth come other impacts for the near-Earth space environment. <a href="https://theconversation.com/divert-power-to-shields-the-solar-maximum-is-coming-11228">Geomagnetic storms</a>, like the one currently in progress, are known to wreak havoc on a range of satellite and ground-based communication technologies, as well as <a href="https://theconversation.com/damaging-electric-currents-in-space-affect-earths-equatorial-region-not-just-the-poles-45073">power grids</a>, GPS/GNSS, and orbit predictions of satellites and space debris. It is also very likely to produce dazzling aurora activity as far south as the northern U.S. and Europe in the Northern Hemisphere, and as far north as southern Australia and New Zealand in the Southern Hemisphere. </p>
<p>While scientists and aurora-hunting enthusiasts closely watch the storm’s ongoing effects, others will be bracing for problems and disruptions to the many technological services that will be affected.</p>
<p>We don’t need to worry about this coronal mass ejection being “the big one” – a solar storm direct hit that could cause widespread power blackouts and trigger <a href="https://science.nasa.gov/science-news/science-at-nasa/2014/23jul_superstorm/">as much as US$2 trillion worth of damage</a>, according to a National Academy of Sciences study. But this storm, on the back of this month’s abnormally active space weather, may wind up on the larger end of the scale, and will be the subject of lots of analysis and research.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/185120/original/file-20170907-9568-1nt2u26.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/185120/original/file-20170907-9568-1nt2u26.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/185120/original/file-20170907-9568-1nt2u26.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/185120/original/file-20170907-9568-1nt2u26.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/185120/original/file-20170907-9568-1nt2u26.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/185120/original/file-20170907-9568-1nt2u26.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/185120/original/file-20170907-9568-1nt2u26.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/185120/original/file-20170907-9568-1nt2u26.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"></a>
<figcaption>
<span class="caption">Images of the sun during solar cycle 23. You typically see more activity during a solar maximum (2001) than during a minimum (1996 or 2006).</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/mission_pages/sunearth/science/solarcycle23.html">ESA&NASA/SoHO</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>We don’t yet fully understand everything that is happening. But the activity over the past few days, when the sun should be within its quietest period, shows that significant space weather events are possible at any stage of the 11-year solar cycle.</p>
<p>You can help us study this and other solar storms as a citizen scientist. Sign up for <a href="http://www.aurorasaurus.org/">Aurorasaurus</a> and let us know if you observe aurorae with this event.</p><img src="https://counter.theconversation.com/content/83677/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alexa Halford receives funding from NASA. </span></em></p><p class="fine-print"><em><span>Brett Carter receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Julie Currie receives funding from the Australian Research Council. </span></em></p>At a time in the sun’s cycle when space weather experts expect less solar activity, our star is going bonkers with solar flares and coronal mass ejections. What effects will Earth feel?Alexa Halford, Researcher in Physics and Astronomy, Dartmouth CollegeBrett Carter, Senior Research Fellow, RMIT UniversityJulie Currie, Research Officer, RMIT UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/562752016-03-17T04:34:11Z2016-03-17T04:34:11ZWhat the ‘weather’ is like on a star can help in the search for life<figure><img src="https://images.theconversation.com/files/115379/original/image-20160317-30211-1m1jg4l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">An artist’s illustration of Kappa Ceti whose stellar winds are 50 times stronger than our sun’s. Any Earth-like planet would need a magnetic field to protect its atmosphere if it was to stand a chance of hosting life.</span> <span class="attribution"><span class="source">M. Weiss/CfA</span></span></figcaption></figure><p>Scientists are studying the “weather” around young sun-like stars in an attempt to understand the conditions needed for a system to have planets that <a href="https://theconversation.com/what-makes-one-earth-like-planet-more-habitable-than-another-33479">would stand a chance of hosting life</a>.</p>
<p><a href="http://simbad.u-strasbg.fr/simbad/sim-id?Ident=HD+20630">Kappa Ceti</a> is a relatively nearby star that <a href="http://www.solstation.com/stars/kap-ceti.htm">resembles our sun in its youth</a>, when it was just half-a-billion years old. But the <a href="http://arxiv.org/abs/1603.03937">results of a detailed study</a> of Kappa Ceti released overnight reveal a star far more violent and active than our modern-day sun.</p>
<p>When we look at stars in the night sky, we often imagine serene glowing balls of gas that will illuminate the universe for billions of years. </p>
<p>But stars give off more than just light. They shed material, continually flooding their environment with a <a href="http://astronomy.swin.edu.au/cosmos/S/stellar+winds">stellar wind</a>. They also emit vast explosions of material, <a href="http://hesperia.gsfc.nasa.gov/sftheory/flare.htm">flares</a> and <a href="http://solarscience.msfc.nasa.gov/CMEs.shtml">mass ejections</a>, continually flinging their outer layers into space.</p>
<p>This flood of material spewing from a star is known as <a href="http://spaceweather.com/">space weather</a> and, until recently, it has proven incredibly challenging for astronomers to study on any star other than the sun.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/115369/original/image-20160317-30203-x8blvm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/115369/original/image-20160317-30203-x8blvm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/115369/original/image-20160317-30203-x8blvm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/115369/original/image-20160317-30203-x8blvm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/115369/original/image-20160317-30203-x8blvm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/115369/original/image-20160317-30203-x8blvm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/115369/original/image-20160317-30203-x8blvm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/115369/original/image-20160317-30203-x8blvm.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">Our sun burps, on August 31, 2012, flinging material into space as part of a coronal mass ejection.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/gsfc/7931831962">Flickr/NASA Goddard Space Flight Centre</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Measuring a star’s activity</h2>
<p>An important question in astrobiology is: “how normal is our sun?”. Is our star unusual, with life an accidental beneficiary? Or are there other sun-like stars capable of hosting planets with life? </p>
<p>The problem is that stars are <a href="http://imagine.gsfc.nasa.gov/features/cosmic/nearest_star_info.html">very far away</a>. Even the <a href="http://hubblesite.org/newscenter/archive/releases/1996/04/image/a/">most powerful telescopes</a> can barely resolve the disks of even the largest stars. So how can we study the weather generated by those stars? </p>
<p>To do this, the scientists in the <a href="https://bcool.irap.omp.eu">BCool consortium</a> take advantage of the fact that stars, particularly active ones, have strong magnetic fields that are intimately tied to the star’s activity. </p>
<p>As light (an electromagnetic wave) passes through a strong magnetic field, it becomes polarised. The degree and type of polarisation depends on both the direction and the strength of the magnetic field. </p>
<p>It is this polarisation that the BCool scientists measure to study the magnetic fields of sun-like stars. They observe those stars in polarised light (a bit like putting polarised sunglasses on the telescope), which allows them to map the magnetic field on the surface of the star. </p>
<p>From this, they calculate how the field extends outward from the star, and how it evolves with time. This allows them to determine the stellar wind and to model the impact of that wind on any orbiting planets.</p>
<h2>A younger star</h2>
<p>Kappa Ceti is located 30 light-years from Earth, in the constellation of <a href="http://www.ianridpath.com/startales/cetus.htm">Cetus</a> (the Whale).</p>
<p>It is very similar to our sun – about as massive, as bright and as hot. But while our sun is very much middle-aged, Kappa Ceti is far younger. At between 400 and 800 million years old, Kappa Ceti is probably a good analogue for what our sun was like back when life was first getting a foothold on Earth. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/115201/original/image-20160315-25487-dmprma.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/115201/original/image-20160315-25487-dmprma.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/115201/original/image-20160315-25487-dmprma.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=538&fit=crop&dpr=1 600w, https://images.theconversation.com/files/115201/original/image-20160315-25487-dmprma.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=538&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/115201/original/image-20160315-25487-dmprma.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=538&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/115201/original/image-20160315-25487-dmprma.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=676&fit=crop&dpr=1 754w, https://images.theconversation.com/files/115201/original/image-20160315-25487-dmprma.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=676&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/115201/original/image-20160315-25487-dmprma.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=676&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 computer model showing the magnetic field lines of Kappa Ceti (gray lines) looping out from the star’s surface. These magnetic fields generate a stellar wind 50 times stronger than our sun’s.</span>
<span class="attribution"><span class="source">TCD / A Vidotto Do Nascimento et. al (2016). ApJLetters</span></span>
</figcaption>
</figure>
<p>Similar to other young stars, Kappa Ceti has been found to be very magnetically active. Its surface is littered with large starspots – stellar acne resulting from the cooling effect of magnetic fields erupting through the stellar surface.</p>
<p>While our sun also has spots, those on stars such as Kappa Ceti are far larger and more numerous, the result of a much stronger magnetic field.</p>
<p>Such a strong magnetic field propels a stream of plasma (ionised gas) into space, with this stellar wind being 50 times stronger than that of our sun.</p>
<p>What would that mean for any planets around such a star? Would they be able to survive the onslaught?</p>
<h2>Stellar winds and atmospheres</h2>
<p>Stellar winds can be dangerous things. Without protection, a star’s wind can <a href="http://mars.nasa.gov/news/whatsnew/index.cfm?FuseAction=ShowNews&NewsID=1869">strip the atmosphere from a planet</a>, leaving it an airless husk. And a stronger wind poses more of a threat than a weaker one.</p>
<p>Fortunately, planets often come with their own shield, a magnetic field of their very own that can protect them from their host star’s worst excesses. </p>
<p>This is nicely seen here on Earth. The great majority of the solar wind is deflected around our planet. Only the most energetically flung particles break through, following the Earth’s magnetic field to the poles, where they trigger the beautiful Aurora Borealis and Australis.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/GW8o62mlQdo?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>But would the Earth’s magnetic field stand up to a wind as strong as Kappa Ceti’s? The BCool team looked into this. It’s thought that when the Earth was young, its magnetic field was probably <a href="http://www.sciencedirect.com/science/article/pii/S003192019900103X?np=y">no stronger than it is today</a>. </p>
<p>As it turns out, our magnetic field would have been enough, even if our sun was once as active as Kappa Ceti. The Earth’s shield, the magnetosphere, would have been compressed, shrunk to about one-third its current size. But it would have endured, protecting Earth and allowing our planet to remain habitable.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/115396/original/image-20160317-30244-1j3fqth.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/115396/original/image-20160317-30244-1j3fqth.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/115396/original/image-20160317-30244-1j3fqth.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=328&fit=crop&dpr=1 600w, https://images.theconversation.com/files/115396/original/image-20160317-30244-1j3fqth.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=328&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/115396/original/image-20160317-30244-1j3fqth.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=328&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/115396/original/image-20160317-30244-1j3fqth.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=412&fit=crop&dpr=1 754w, https://images.theconversation.com/files/115396/original/image-20160317-30244-1j3fqth.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=412&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/115396/original/image-20160317-30244-1j3fqth.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=412&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 rendition of Earth’s magnetosphere.</span>
<span class="attribution"><span class="source">NASA</span></span>
</figcaption>
</figure>
<p>Mars, however, was not so lucky. It’s a smaller planet and its interior cooled more quickly than the Earth’s, quashing the internal dynamo that drives our planet’s magnetic shield.</p>
<p>Without a strong magnetic field, Mars was exposed to the full force of the sun’s youthful rage. Over the aeons, its atmosphere has been <a href="http://www.nasa.gov/press-release/nasa-mission-reveals-speed-of-solar-wind-stripping-martian-atmosphere/">slowly stripped away</a>. At the same time, the remains were drawn down, chemically trapped in the planet’s surface. </p>
<p>The result is a frigid, arid world, with an atmosphere just a tenuous wisp of its former glory. </p>
<h2>The search for life out there</h2>
<p>Astronomers should soon begin to discover the first truly Earth-like planets orbiting other stars, and the race will be on to search for evidence of life upon them. But where should we look? </p>
<p>To choose the most promising targets, those scientists will have to consider the many factors that can make one planet more liveable than another. So the <a href="https://theconversation.com/for-life-to-form-on-a-planet-it-needs-to-orbit-the-right-kind-of-star-33477">nature of the planet’s host star</a> will play a vital role.</p>
<p>By studying stars such as Kappa Ceti, we are building an understanding of how stars and planets interact. Once those first exo-Earths are found, it will be possible to measure and characterise the winds of their host stars. This will then help us determine which of those planets to target in the search for life elsewhere.</p><img src="https://counter.theconversation.com/content/56275/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>In the search for life on other planets in the universe we need to find the right kind of star, and it needs to have the right kind of space weather.Jonti Horner, Vice Chancellor's Senior Research Fellow, University of Southern QueenslandStephen Marsden, Senior Lecturer (Astronomy), University of Southern QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/503412015-11-09T15:16:50Z2015-11-09T15:16:50ZWhat’s it like to see auroras on other planets?<figure><img src="https://images.theconversation.com/files/101275/original/image-20151109-29341-pe4xmd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Aalto University</span></span></figcaption></figure><p>Witnessing an aurora first-hand is a truly awe-inspiring experience. The natural beauty of the northern or southern lights captures the public imagination unlike any other aspect of space weather. But auroras aren’t unique to Earth and can be seen on several other planets in our solar system.</p>
<p><a href="https://theconversation.com/what-caused-those-spectacular-northern-lights-and-how-you-can-catch-them-next-time-39081">An aurora</a> is the impressive end result of a series of events that starts at the sun. The sun constantly emits a stream of charged particles known as the solar wind into the depths of the solar system. When these particles reach a planet, such as Earth, they interact with the magnetic field surrounding it (the magnetosphere), compressing the field into a teardrop shape and transferring energy to it.</p>
<p>Because of the way the lines of a magnetic field can change, the charged particles inside the magnetosphere can then be accelerated into the upper atmosphere. Here they collide with molecules such as nitrogen and oxygen, giving off energy in the form of light. This creates a ribbon of colour that can be seen across the sky close to the planet’s magnetic north and south poles – this is the aurora.</p>
<h2>Gas giant auroras</h2>
<p>Using measurements from spacecraft, such as <a href="http://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens">Cassini</a>, or images from telescopes, such as the <a href="http://hubblesite.org/">Hubble Space Telescope</a>, space physicists have been able to verify that some of our closest neighbours have their own auroras. Scientists do this by studying the electromagnetic radiation received from the planets, and certain wavelength emissions are good indicators of the presence of auroras.</p>
<p>Each of the gas giants (Jupiter, Saturn, Uranus, and Neptune) has a strong magnetic field, a dense atmosphere and, as a result, its own aurora. The exact nature of these auroras is slightly different from Earth’s, since their atmospheres and magnetospheres are different. The colours, for example, depend on the gases in the planet’s atmosphere. But the fundamental idea behind the auroras is the same.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/101276/original/image-20151109-29326-1md6x8a.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/101276/original/image-20151109-29326-1md6x8a.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=342&fit=crop&dpr=1 600w, https://images.theconversation.com/files/101276/original/image-20151109-29326-1md6x8a.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=342&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/101276/original/image-20151109-29326-1md6x8a.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=342&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/101276/original/image-20151109-29326-1md6x8a.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=430&fit=crop&dpr=1 754w, https://images.theconversation.com/files/101276/original/image-20151109-29326-1md6x8a.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=430&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/101276/original/image-20151109-29326-1md6x8a.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=430&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Blue aurora on Jupiter.</span>
<span class="attribution"><span class="source">NASA/J Clarke</span></span>
</figcaption>
</figure>
<p>For example, several of Jupiter’s moons, including Io, Ganymede and Europa, affect the blue aurora created by the solar wind. Io, which is just a little larger than our own moon, is volcanic and spews out vast amounts of charged particles into Jupiter’s magnetosphere, <a href="http://www.space.com/29248-jupiter-auroras-volcanic-moon-io.html">producing large electrical currents</a> and bright ultraviolet (UV) aurora.</p>
<p>On Saturn, the strongest auroras are in the UV and infrared bands of the colour spectrum and so would not be visible to the human eye. But weaker (and rarer) pink and purple auroras <a href="http://www.sciencedirect.com/science/article/pii/S0019103515002328">have also been spotted</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/101162/original/image-20151108-16255-11oqoqm.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/101162/original/image-20151108-16255-11oqoqm.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=591&fit=crop&dpr=1 600w, https://images.theconversation.com/files/101162/original/image-20151108-16255-11oqoqm.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=591&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/101162/original/image-20151108-16255-11oqoqm.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=591&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/101162/original/image-20151108-16255-11oqoqm.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=743&fit=crop&dpr=1 754w, https://images.theconversation.com/files/101162/original/image-20151108-16255-11oqoqm.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=743&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/101162/original/image-20151108-16255-11oqoqm.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=743&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Hubble Space Telescope captures Saturn’s aurora.</span>
<span class="attribution"><span class="source">NASA/ESA/Hubble</span></span>
</figcaption>
</figure>
<p>Mercury also has a magnetosphere and so we might expect aurora there too. Unfortunately, Mercury is too small and too close to the sun for it to retain an atmosphere, meaning the planet doesn’t have any molecules for the solar wind to excite and that means no auroras.</p>
<h2>The unexpected auroras</h2>
<p>On Venus and Mars, the story is different. While neither of these planets has a large-scale magnetic field, both have an atmosphere. As the solar wind interacts with the Venusian ionosphere (the layer of the atmosphere with the most charged particles), it actually creates or induces a magnetic field. Using data from the <a href="http://www.esa.int/Our_Activities/Space_Science/Venus_Express">Venus Express</a> spacecraft, <a href="http://www.sciencemag.org/content/336/6081/567">scientists found</a> that this magnetic field stretches out away from the sun to form a “magnetotail” that redirects accelerated particles into the atmosphere and forms an aurora.</p>
<p><a href="https://theconversation.com/how-did-mars-lose-its-habitable-climate-the-answer-is-blowing-in-the-solar-wind-50258">Mars’s atmosphere is too thin</a> for a similar process to occur there, but it still has aurora created by localised magnetic fields embedded in the planet’s crust. These are the remnants of a much larger, global magnetic field that disappeared as the planet’s core cooled. Interaction between the solar wind and the Martian atmosphere generates “discrete” auroras that are confined to the regions of crustal field. </p>
<p>A [recent discovery]([(https://theconversation.com/how-did-mars-lose-its-habitable-climate-the-answer-is-blowing-in-the-solar-wind-50258) by the <a href="https://www.nasa.gov/mission_pages/maven/main/index.html">MAVEN mission</a> showed that Mars also has much larger auroras spread across the northern hemisphere, and probably the whole planet too. This “diffuse” aurora is the result of solar energetic particles raining into the Martian atmosphere, rather than particles from the solar wind interacting with a magnetic field.</p>
<p>If an astronaut were to stand on the surface of Mars, they might still see an aurora but it would likely be rather faint and blue, and, unlike on Earth, not be necessarily near the planet’s poles.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/101272/original/image-20151109-29333-u6cfas.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/101272/original/image-20151109-29333-u6cfas.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/101272/original/image-20151109-29333-u6cfas.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/101272/original/image-20151109-29333-u6cfas.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/101272/original/image-20151109-29333-u6cfas.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/101272/original/image-20151109-29333-u6cfas.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/101272/original/image-20151109-29333-u6cfas.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">Brown dwarf with red aurora.</span>
<span class="attribution"><span class="source">Chuck Carter and Gregg Hallinan/Caltech</span></span>
</figcaption>
</figure>
<p>Most planets outside our solar system are too dim compared to their parent star for us to see if they have auroras. But scientists <a href="http://www.nature.com/nature/journal/v523/n7562/full/nature14619.html">recently discovered</a> a brown dwarf (an object bigger than a planet but not big enough to burn like a star) 18 light years from Earth that is believed to have a bright red aurora. This raises the possibility of discovering other exoplanets with atmospheres and magnetic fields that have their own auroras.</p>
<p>Such discoveries are exciting and beautiful, but they are also scientifically useful. Investigating auroras gives scientists tantalising clues about a planet’s magnetic and particle environment and could further our understanding of how charged particles and magnetic fields interact. This could even unlock the answers to other physics problems, <a href="http://news.mit.edu/2010/fusion-ldx-0125">such as nuclear fusion</a>.</p><img src="https://counter.theconversation.com/content/50341/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nathan Case receives funding from the Science and Technology Facilities Council. Nathan is a member of the AuroraWatch UK team at Lancaster University which issues alerts of potential aurora visibility from the UK.</span></em></p>Recent Martian findings are just the latest discoveries of aurora on other planets, both in and out of our solar system.Nathan Case, Senior Research Associate in Space and Planetary Physics, Lancaster UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/466362015-08-28T13:30:17Z2015-08-28T13:30:17ZSix amazing sights that look even better from the International Space Station<figure><img src="https://images.theconversation.com/files/92927/original/image-20150825-15875-1pkpm9z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Hurricane Arthur photographed by ESA astronaut Alexander Gerst.</span> <span class="attribution"><span class="source">ESA/NASA</span></span></figcaption></figure><p>Imagine seeing the lights of cities spreading around <a href="http://www.nasa.gov/multimedia/imagegallery/image_feature_1923.html">the Nile Delta</a> and then in less than an hour gazing down on <a href="http://www.nasa.gov/multimedia/imagegallery/image_feature_152.html">Mount Everest</a>. The astronauts on the <a href="http://www.nasa.gov/mission_pages/station/main/index.html">International Space Station</a> (ISS) are among the lucky few who will have this humbling, once-in-a-lifetime experience of seeing the beauty of Earth from space. </p>
<p>The ISS doesn’t just offer spectacular and countless views of the natural and man-made landscapes of our planet. It also immerses its residents into the Earth’s space environment and reveals how dynamic its atmosphere is, from its lower layers to its protective <a href="http://www.swpc.noaa.gov/phenomena/earths-magnetosphere">magnetic shield</a>, constantly swept by the solar wind.</p>
<p>The best views are seen from <a href="http://www.esa.int/Our_Activities/Human_Spaceflight/Views_from_Cupola">the Cupola</a>, an observation deck module attached to the ISS in 2010 and comprising seven windows. So, what are the amazing sights that you can see from the space station?</p>
<h2>1. Storms and lightning</h2>
<p>When the ISS orbits over a sea of thunderclouds, it’s not rare for astronauts to witness an impressive amount of lightning. What is unusual, however, is seeing lightning sprites, which were <a href="http://earthobservatory.nasa.gov/IOTD/view.php?id=86463">observed on August 10th</a> by astronauts aboard the space station.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/92911/original/image-20150825-17055-o3talf.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/92911/original/image-20150825-17055-o3talf.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/92911/original/image-20150825-17055-o3talf.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/92911/original/image-20150825-17055-o3talf.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/92911/original/image-20150825-17055-o3talf.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/92911/original/image-20150825-17055-o3talf.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/92911/original/image-20150825-17055-o3talf.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">ISS astronauts spotted a sprite (the red jellyfish-like structure on the right of the image) appearing above thunder clouds on August 10, 2015.</span>
<span class="attribution"><span class="source">NASA</span></span>
</figcaption>
</figure>
<p>Sprites are electrical discharges, similar to thunder lights. However, instead of occurring in the lower layer of Earth’s atmosphere, these very fast, red-coloured discharges (due to the excited nitrogen at this altitude) occur much higher up and are as such difficult to observe from the ground.</p>
<h2>2. Sunrises and sunsets</h2>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/92928/original/image-20150825-15896-1ar0fkw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/92928/original/image-20150825-15896-1ar0fkw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/92928/original/image-20150825-15896-1ar0fkw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/92928/original/image-20150825-15896-1ar0fkw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/92928/original/image-20150825-15896-1ar0fkw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/92928/original/image-20150825-15896-1ar0fkw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/92928/original/image-20150825-15896-1ar0fkw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Sunset over the Indian Ocean.</span>
<span class="attribution"><span class="source">NASA/ESA/G Bacon</span></span>
</figcaption>
</figure>
<p>With the ISS orbiting the Earth every 90 minutes, astronauts can see the Sun rise and set around 16 times every 24 hours. The dramatic views from the station display a rainbow-like horizon as the Sun appears and disappears beyond the horizon.</p>
<p>The changes in colour are due to the angle of the solar rays and their scattering in the Earth’s atmosphere. If similar jaw-dropping views can be seen from Earth, seeing our mother planet lit up in the rising Sun certainly adds to the intensity of the picture.</p>
<h2>3. Stars and the Milky Way</h2>
<figure>
<iframe src="https://player.vimeo.com/video/38409143" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
<figcaption><span class="caption">Amazing sightings of distant astronomical objects as seen from the space shuttle.</span></figcaption>
</figure>
<p>From the ground, atmospheric conditions and light pollution affect our ability to see stars and other celestial bodies. As light travels through layers of hot and cold air, the bending of its rays render a flickering image of these distant objects, while atmospheric particles such as dust prevent from seeing fainter objects such as nebulae and galaxies.</p>
<p>The lack of an atmosphere at the orbiting altitude of the ISS allows the residents on the space station to see the stars, the Milky Way and other astronomical features with much greater clarity than is possible on Earth.</p>
<h2>4. Meteor showers</h2>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/92916/original/image-20150825-17096-duu601.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/92916/original/image-20150825-17096-duu601.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/92916/original/image-20150825-17096-duu601.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/92916/original/image-20150825-17096-duu601.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/92916/original/image-20150825-17096-duu601.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/92916/original/image-20150825-17096-duu601.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/92916/original/image-20150825-17096-duu601.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 disintegration of a Perseid meteor photographed in August 2011 from the ISS.</span>
<span class="attribution"><span class="source">NASA</span></span>
</figcaption>
</figure>
<p>Astronauts aboard the ISS can also witness the disintegration of meteoroids in the Earth’s atmosphere. Those small bodies are fragments detached from celestial bodies such as asteroids and comets. As they enter in the Earth’s atmosphere at great speed, the heat due to the body interaction with air rapidly destroys them. Whereas the chance of seeing them from the ground is very much weather dependent, being on the ISS guarantees the best seats to watch these shooting stars flaming across our planet’s sky.</p>
<h2>5. Auroras</h2>
<p>Also known as northern and southern lights, auroras are created when solar storms, consisting of large magnetised clouds of energetic particles launched from the sun, or strong <a href="http://www.swpc.noaa.gov/phenomena/solar-wind">solar wind</a>, interact with the Earth’s magnetic shield. Upon collision with the Earth, these solar streams energise particles within the planet’s magnetic shield.</p>
<figure>
<iframe src="https://player.vimeo.com/video/130263115" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
<figcaption><span class="caption">Time lapses showing the ISS travelling through auroras.</span></figcaption>
</figure>
<p>When they enter the upper layer of the Earth’s atmosphere, these energetic particles excite nitrogen and oxygen atoms present at these altitudes. Then when they return from their excited state, these atoms emit light of different colours indicative of the amount of energy they absorbed. This typically produces green and red, ribbon-like curtains. </p>
<h2>6. Cosmic rays</h2>
<p><a href="http://helios.gsfc.nasa.gov/gcr.html">Galactic cosmic rays</a> aren’t really a phenomenon you can see. These energetic sub-atomic particles come from intense astronomical sources such as exploding stars or black holes. If they pass into the body they can damage tissue and break DNA, causing various diseases over the course of time.</p>
<p>Most cosmic rays do not penetrate in the thick atmosphere of the Earth. Since the ISS sits outside this protected zone, its astronauts are much more likely to be struck by the particles. Astronauts regularly see <a href="http://www.sciencedirect.com/science/article/pii/S0042698905006735">flashes of light</a> when they close their eyes, which is thought to be caused by cosmic rays interacting with body parts that play role in vision, such as the optic nerve or visual centres in the brain.</p>
<p>Solar storms, which have a strong magnetic structure, act as a shield against cosmic rays. A solar storm passing by the Earth can be indirectly witnessed by astronauts aboard the ISS via a drop in the count of cosmic rays, also known as the “<a href="http://science.nasa.gov/science-news/science-at-nasa/2005/07oct_afraid/">Forbush decrease</a>”. What a sensation it must be to “feel” a storm passing by the Earth’s system.</p><img src="https://counter.theconversation.com/content/46636/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Miho Janvier 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>Astronauts living on the ISS get to experience the wonders of the universe’s natural phenomena like no one else.Miho Janvier, Lecturer in Mathematics, University of DundeeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/450732015-08-17T09:43:01Z2015-08-17T09:43:01ZDamaging electric currents in space affect Earth’s equatorial region, not just the poles<figure><img src="https://images.theconversation.com/files/91512/original/image-20150811-32001-h7ezzh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">When the sun flares, space weather is on its way to Earth.</span> <span class="attribution"><a class="source" href="http://www.nasa.gov/image-feature/solar-dynamics-observatory-sees-m79-class-solar-flare">NASA/SDO</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>The Earth’s magnetic field – known as the “magnetosphere” – protects our atmosphere from the “solar wind.” That’s the constant stream of charged particles flowing outward from the sun. When the magnetosphere shields Earth from these solar particles, they get funneled toward the polar regions of our atmosphere. </p>
<p>As the particles crash into the atmosphere’s ionospheric layer, light is given off, creating beautiful multicolored displays of <a href="https://theconversation.com/what-caused-those-spectacular-northern-lights-and-how-you-can-catch-them-next-time-39081">aurora</a> near both the North and South Poles. These are stunning visual representations of the complex interactions in the near-Earth space environment, which we collectively term “space weather.” </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/91511/original/image-20150811-11104-pjxls4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/91511/original/image-20150811-11104-pjxls4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/91511/original/image-20150811-11104-pjxls4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/91511/original/image-20150811-11104-pjxls4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/91511/original/image-20150811-11104-pjxls4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/91511/original/image-20150811-11104-pjxls4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/91511/original/image-20150811-11104-pjxls4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/91511/original/image-20150811-11104-pjxls4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Aurora over Norway, visual of space weather.</span>
<span class="attribution"><span class="source">Alexa Halford</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>The same space weather that generates these beautiful displays can cause havoc for a wide range of <a href="https://theconversation.com/divert-power-to-shields-the-solar-maximum-is-coming-11228">technologies</a>. We’ve known for a while that space weather in high-latitude regions near the poles can cause power grid failures, sometimes causing heavy damage. <a href="http://doi.org/10.1029/89EO00409">The most famous</a> instance was the March 1989 blackout in the Northeastern US and up through Quebec, Canada that left millions without power for 12 hours.</p>
<p>But we haven’t thought of equatorial regions as being prime targets. Our new research shows that areas closer to the equator still experience bad space weather – and its disturbing effects on power grid infrastructure.</p>
<h2>Changing magnetic fields crank up electric currents</h2>
<p>High above the ground in the upper atmosphere are fluctuating electric currents driven by interactions in the <a href="http://www.swpc.noaa.gov/phenomena/earths-magnetosphere">magnetosphere</a> and <a href="http://www.ips.gov.au/Educational/1/2/5">ionosphere</a>. These atmospheric currents cause strong changes in the strength of the local magnetic field on the ground. We can’t feel the magnetic field ourselves, but researchers <a href="http://www.intermagnet.org/">measure and track it</a> at various points on the Earth’s surface. </p>
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<a href="https://images.theconversation.com/files/91505/original/image-20150811-11104-1ptmk6c.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/91505/original/image-20150811-11104-1ptmk6c.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/91505/original/image-20150811-11104-1ptmk6c.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/91505/original/image-20150811-11104-1ptmk6c.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/91505/original/image-20150811-11104-1ptmk6c.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/91505/original/image-20150811-11104-1ptmk6c.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/91505/original/image-20150811-11104-1ptmk6c.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/91505/original/image-20150811-11104-1ptmk6c.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"></a>
<figcaption>
<span class="caption">Dr Endawoke Yizengaw next to a magnetometer installation that records changes in the magnetic field at that spot in Phuket, Thailand.</span>
<span class="attribution"><span class="source">Endawoke Yizengaw</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>That’s all well and good. The problem comes in when these atmospheric currents cause swift changes in the magnetic field. When the magnetic field abruptly changes, it can generate electric currents in conductors at the Earth’s surface – for instance, long pipes or wires such as <a href="https://www.lloyds.com/%7E/media/lloyds/reports/360/360%20space%20weather/7311_lloyds_360_space%20weather_03.pdf">oil and gas pipelines</a> or <a href="https://eos.org/features/magnetic-storms-induction-hazards">power transmission lines</a>. This process of electric current generation is called <a href="https://www.youtube.com/watch?v=S0wbEl7caTY">magnetic induction</a>.</p>
<p>These electric currents are not-so-creatively called geomagnetically induced currents, or GICs for short. The high-latitude regions are most susceptible to GICs because of the intense electric currents flowing through the auroras, thanks to the way the solar wind gets diverted when it hits the Earth’s magnetosphere. However, the entire planet can be affected to varying degrees.</p>
<p>When they occur, GICs effectively generate extra electric current in power grid infrastructure through magnetic induction. Power grids, during large events, can end up taking on more electricity than they can handle. These induced currents have caused numerous <a href="http://aurora.fmi.fi/gic_service/english/about_ground_effects.html">equipment failures</a> that have led to power outages for large populations.</p>
<figure><img src="https://cdn.theconversation.com/static_files/files/28/animate6.gif?1518674322"><figcaption><span class="caption">Modeled location of the equatorial electrojet from the viewpoint of a satellite sitting at about 10:00 am local time (Alken and Maus, 2007).</span></figcaption></figure>
<h2>Trouble at the equator too, not just near the poles</h2>
<p>Those same geomagnetically induced currents that happen in the high-latitude regions can happen around the equator of our planet too. There, they are caused not by the auroral electric current system we find near the poles, but by a weaker low-latitude counterpart called the <a href="http://geomag.org/info/equatorial_electrojet.html">equatorial electrojet</a>. Like the high-latitude ionospheric current system, the equatorial electrojet’s electric current can be detected on the ground using magnetic field observations.</p>
<p>Recently researchers <a href="http://dx.doi.org/10.1029/2011SW000750">reported</a> that GIC activity is enhanced at the equator during severe geomagnetic storms – that’s when solar eruptions called “<a href="http://www.space.com/11506-space-weather-sunspots-solar-flares-coronal-mass-ejections.html">coronal mass ejections</a>” trigger shock waves that hit the Earth. They pointed the finger at the equatorial electrojet as a suspected cause.</p>
<p>In our new research article in <a href="http://doi.org/10.1002/2015GL065060">Geophysical Research Letters</a>, we show that countries near the <a href="http://www.bu.edu/cism/cismdx/ref/Labs/2005_AFWA_ShortCourse/Lab03/refs/EarthMagneticField.pdf">magnetic equator</a> are more vulnerable to space weather than previously thought.</p>
<p>Rather than focusing on <a href="https://theconversation.com/solar-eruption-could-help-earth-prepare-for-technology-melt-down-18747">severe geomagnetic storms</a>, such as the <a href="http://www.space.com/23396-scary-halloween-solar-storm-2003-anniversary.html">2003 Halloween event</a> that caused power grid problems in Sweden (among many <a href="http://www.nws.noaa.gov/os/assessments/pdfs/SWstorms_assessment.pdf">other things</a>), we took a different tack. Our analysis focused on the arrival of interplanetary shocks. These are abrupt pressure increases in the solar wind - that stream of plasma constantly flowing out of the sun. When these shocks hit the Earth’s magnetosphere, the impact causes a sudden magnetic field change that can be measured all over the world.</p>
<p>Interplanetary shocks regularly announce the beginning of a geomagnetic storm. But many pass by relatively benignly without developing into a full-blown geomagnetic storm. We noticed that the magnetic response to these shock arrivals was sometimes significantly stronger at the magnetic equator when compared to locations only a few degrees away. Why?</p>
<p>An analysis of how these equatorial responses differed throughout the day revealed they were strongest around noon and weakest at night. This daily contrast corresponds to the well-known variations in the equatorial electrojet. It’s strong evidence that the equatorial electrojet is amplifying the geomagnetically induced current activity during interplanetary shock arrivals in a way that hasn’t really been recognized until now.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/91510/original/image-20150811-11091-1wtqiwj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/91510/original/image-20150811-11091-1wtqiwj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/91510/original/image-20150811-11091-1wtqiwj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/91510/original/image-20150811-11091-1wtqiwj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/91510/original/image-20150811-11091-1wtqiwj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/91510/original/image-20150811-11091-1wtqiwj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=425&fit=crop&dpr=1 754w, https://images.theconversation.com/files/91510/original/image-20150811-11091-1wtqiwj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=425&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/91510/original/image-20150811-11091-1wtqiwj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=425&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Nonpolar power grids can get hit by space weather, too.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/kendoerr/8079981829">Ken Doerr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Effects on equatorial power grids</h2>
<p>This result has significant implications for the many countries located beneath the equatorial electrojet that may be operating power infrastructure not initially designed to cope with space weather. These countries need to look into ways of protecting their infrastructure during geomagnetically quiet periods as well as during severe geomagnetic storms.</p>
<p>One of our coauthors, Dr <a href="https://www2.bc.edu/endawoke-kassie/">Endawoke Yizengaw</a> from Boston College, grew up in Ethiopia, within the equatorial electrojet’s region of influence. He recalls regular unexplained power outages during his childhood and wonders whether interplanetary shocks may have played a role. We hope to be able to answer this question in the near future.</p>
<p>Scientists around the world are conducting ongoing research to better understand the effects of these geomagnetically induced currents on power grids. It’s becoming increasingly clear that we need to investigate the effects of quiet periods, not just major events. What happens during these quiet times, and in regions often overlooked, can have a significant impact on our increasingly technology-dependent society.</p><img src="https://counter.theconversation.com/content/45073/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Brett Carter receives funding from the Victorian Government Department of Business and Innovation and the Australian Research Council.</span></em></p><p class="fine-print"><em><span>Alexa Halford receives funding from NASA through multiple grants, primarily NNX08AM58G (BARREL). Alexa is also a member of the Sierra Club.</span></em></p>Our power grid infrastructure on Earth is more vulnerable to space weather than previously thought – with susceptibility in more regions and even during quiet geomagnetic periods.Brett Carter, Senior Research Fellow, RMIT UniversityAlexa Halford, Researcher in Physics and Astronomy, Dartmouth CollegeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/391132015-04-01T19:09:55Z2015-04-01T19:09:55ZFire in the sky: The southern lights in Indigenous oral traditions<figure><img src="https://images.theconversation.com/files/76189/original/image-20150326-8716-7y646s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Aurora Australis as seen from Victoria.</span> <span class="attribution"><a class="source" href="http://www.terrastro.com/galleries/red-aurora/">Alex Cherney, Terrastro Gallery</a>, <span class="license">Author provided</span></span></figcaption></figure><p>Parts of Australia have been privileged to see dazzling lights in the night sky as the Aurora Australis – known as the southern lights – <a href="https://theconversation.com/dazzled-by-the-bright-southern-lights-39129">puts on a show</a> this year.</p>
<p>A recent surge in solar activity caused spectacular auroral displays across the world. While common over the polar regions, aurorae are rare over Australia and are typically restricted to far southern regions, such as Tasmania and Victoria.</p>
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<p>But recently, aurorae have been visible over the whole southern half of Australia, seen as far north as Uluru and Brisbane.</p>
<h2>Different cultures</h2>
<p>It’s a phenomenon that has existed since the Earth’s formation and has been witnessed by cultures around the world. These cultures developed their own explanation for the lights in the sky – many of which are strikingly similar.</p>
<p>From a scientific point of view, aurora form when charged particles of solar wind are channelled to the polar regions by Earth’s magnetic field. These particles ionize oxygen and nitrogen molecules in the upper atmosphere, creating light.</p>
<p>Auroral displays can show various colours, from white, to yellow, red, green, and blue. They can appear as a nebulous glowing arcs or curtains waving across the sky.</p>
<p>Aurorae are also reported to make <a href="http://www.space.com/16498-northern-lights-clapping-sound-explained.html">strange sounds</a> on rare occasions. Witnesses describe it as a crackling sound, like rustling grass or radio static.</p>
<p>In the Arctic, the <a href="http://www.damninteresting.com/the-sound-of-the-aurora/">Inuit</a> say the noise is made by spirits playing a game or trying to communicate with the living.</p>
<p>In 1851, Aboriginal people near Hobart said an aurora made noise like “people snapping their fingers”. The cause of this noise is unknown.</p>
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<p>Aurorae are significant in <a href="https://theconversation.com/stories-from-the-sky-astronomy-in-indigenous-knowledge-33140">Australian Indigenous astronomical traditions</a>. Aboriginal people associate aurorae with fire, death, blood, and omens, sharing many similarities with <a href="http://www.ewebtribe.com/NACulture/articles/aurora.html">Native American</a> communities. They are quite different from Inuit traditions of the Aurora Borealis, which are more festive.</p>
<h2>Fire in the sky</h2>
<p>Aboriginal people commonly saw aurorae as fires in the cosmos. To the Gunditjmara of western Victoria, they’re Puae buae (“ashes”). To the Gunai of eastern Victoria, they’re bushfires in the spirit world and an omen of a coming catastrophe.</p>
<p>The Dieri and Ngarrindjeri of South Australia see aurora as fires created by sky spirits.</p>
<p>As far north as southwestern Queensland, Aboriginal people saw the phenomenon as “feast fires” of the Oola Pikka —- ghostly beings who spoke to Elders through the aurora.</p>
<p>The Maori of Aotearoa/New Zealand saw aurorae (Tahunui-a-rangi) as the campfires of ancestors reflected in the sky. These ancestors sailed southward in their canoes and settled on a land of ice in the far south.</p>
<p>The southern lights let people know they will one day return. This is similar to an <a href="http://www.indigenouspeople.net/aurora.htm">Algonquin story</a> from North America. </p>
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<h2>A warning to follow sacred law</h2>
<p>Mungan Ngour, a powerful sky ancestor in Gunai traditions, set rules for male initiation and put his son, Tundun, in charge of the ceremonies. When people leaked secret information about these ceremonies, Mungan cast down a great fire to destroy the Earth. The people saw this as an aurora.</p>
<p>Near Uluru, a group of hunters broke Pitjantjatjara law by killing and cooking a sacred emu. They saw smoke rise to the south, towards the land of Tjura. This was the aurora, viewed as poisonous flames that signalled coming punishment.</p>
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<p>The Dieri also believe an aurora is a warning that someone is being punished for breaking traditional laws, which causes great fear. The breaking of traditional laws would result in an armed party coming to kill the lawbreakers when they least expect it.</p>
<p>In this context, fear of an aurora was utilised to control behaviour and social standards.</p>
<h2>Blood in the cosmos</h2>
<p>The red hue of some aurorae is commonly associated with blood and death.</p>
<p>To Aboriginal communities across New South Wales, Victoria, and South Australia, auroral displays represented blood that was shed by warriors fighting a great battle in the sky, or by spirits of the dead rising to the heavens.</p>
<p>Celestial events that appear red are often linked to blood, including <a href="http://www.abc.net.au/science/articles/2011/03/15/3160848.htm">meteors</a> and <a href="http://www.abc.net.au/science/articles/2011/06/15/3244593.htm">eclipses</a>.</p>
<p>A total lunar eclipse turns the moon red (sometimes called a blood-moon), which was seen by some communities as the spirit of a dead man rising from his grave.</p>
<p>Rare astronomical events were viewed as bad omens by cultures around the world. Now imagine if two of these events overlap!</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/75481/original/image-20150320-5749-55uma.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/75481/original/image-20150320-5749-55uma.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/75481/original/image-20150320-5749-55uma.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/75481/original/image-20150320-5749-55uma.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/75481/original/image-20150320-5749-55uma.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/75481/original/image-20150320-5749-55uma.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/75481/original/image-20150320-5749-55uma.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/75481/original/image-20150320-5749-55uma.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=499&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 moon turning red during an eclipse, also known as a blood moon.</span>
<span class="attribution"><span class="source">NASA</span></span>
</figcaption>
</figure>
<p>In 1859, Aboriginal people in South Australia witnessed an auroral display <em>and</em> a total lunar eclipse. This caused great fear an anxiety, signalling the arrival of dangerous spirit beings.</p>
<p>There could be a repeat of this astronomical double-act as <a href="https://theconversation.com/be-prepared-for-the-shortest-total-lunar-eclipse-of-the-century-39575">a lunar eclipse</a> will be <a href="http://www.timeanddate.com/eclipse/lunar/2015-april-4">visible across Australia</a> on Saturday April 4, 2015.</p>
<p>Will the aurorae continue? Keep watch.</p>
<hr>
<p>See also: <a href="https://theconversation.com/be-prepared-for-the-shortest-total-lunar-eclipse-of-the-century-39575">Be prepared for the shortest total lunar eclipse of the century</a></p><img src="https://counter.theconversation.com/content/39113/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Duane Hamacher receives funding from the Australian Research Council.</span></em></p>The southern lights that put on a show recently across parts of Australia are easily explained by science. But some cultures have their own explanation for these dazzling lights in the sky.Duane Hamacher, Lecturer and ARC Discovery Early Career Research Fellow, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.