tag:theconversation.com,2011:/id/topics/solar-eclipse-10107/articlesSolar eclipse – The Conversation2024-03-13T19:13:22Ztag:theconversation.com,2011:article/2227072024-03-13T19:13:22Z2024-03-13T19:13:22ZTotal solar eclipses provide an opportunity to engage with science, culture and history<figure><img src="https://images.theconversation.com/files/580943/original/file-20240311-16-li8vda.jpg?ixlib=rb-1.1.0&rect=0%2C5%2C3724%2C2146&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Throughout time, eclipses have inspired societies to understand the cosmos and its events.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>On April 8, 2024, there will be a total solar eclipse in Canada. This is an opportunity to experience, learn from and participate in the excitement and wonder. And rather than hiding inside, researchers have been communicating how people can safely enjoy this unique opportunity.</p>
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Read more:
<a href="https://theconversation.com/on-april-8-2024-parts-of-ontario-quebec-the-maritimes-and-newfoundland-will-see-a-total-eclipse-of-the-sun-heres-how-to-get-ready-for-it-203382">On April 8, 2024, parts of Ontario, Québec, the Maritimes and Newfoundland will see a total eclipse of the sun. Here's how to get ready for it.</a>
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<p>Roughly every 18 months, the sun, moon and Earth come into perfect alignment and somewhere on Earth <a href="https://eclipse.gsfc.nasa.gov/SEatlas/SEatlas.html">experiences a solar eclipse</a>. During this phenomenon, the moon casts a roughly 250 km wide shadow onto Earth.</p>
<p>This ephemeral daytime darkness can be a once-in-a-lifetime experience. The last time Toronto experienced a total solar eclipse was on <a href="http://xjubier.free.fr/en/site_pages/solar_eclipses/xSE_GoogleMap3.php?Ecl=+19250124&Acc=2&Umb=1&Lmt=1&Mag=0&Lat=43.69660&Lng=-79.41391&Elv=162.0&Zoom=8&LC=1">Jan. 24, 1925</a>; the next total solar eclipse will occur in 120 years, on <a href="http://xjubier.free.fr/en/site_pages/solar_eclipses/xSE_GoogleMap3.php?Ecl=+21441026&Acc=2&Umb=1&Lmt=1&Mag=0&Lat=43.69629&Lng=-79.29982&Elv=127.0&Zoom=8&LC=1">Oct. 26, 2144</a>.</p>
<p>Our interpretation of, and response to, total solar eclipses has advanced enormously. Eclipses were once considered cosmic omens that predicted dying kings, good harvests or the need for new territorial treaties. Today, they provide a unique opportunity to consider the physical nature of the universe, and the cosmic privilege of witnessing the alignment of the moon and sun. </p>
<h2>Eclipses and knowledge creation</h2>
<p>Due to their sudden darkness, solar eclipses have been perceived <a href="https://www.cnn.com/2017/07/25/us/history-solar-eclipse/index.html">through history as catastrophic events</a>. Many societies developed stories to <a href="https://www.britannica.com/list/the-sun-was-eaten-6-ways-cultures-have-explained-eclipses">explain these unusual events</a>, often filled with fear and violence. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/580949/original/file-20240311-26-98odlu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="an illustration of a golden brown demon eating a yellow disc against a purple background" src="https://images.theconversation.com/files/580949/original/file-20240311-26-98odlu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/580949/original/file-20240311-26-98odlu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=451&fit=crop&dpr=1 600w, https://images.theconversation.com/files/580949/original/file-20240311-26-98odlu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=451&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/580949/original/file-20240311-26-98odlu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=451&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/580949/original/file-20240311-26-98odlu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=567&fit=crop&dpr=1 754w, https://images.theconversation.com/files/580949/original/file-20240311-26-98odlu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=567&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/580949/original/file-20240311-26-98odlu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=567&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">A mural of the Hindu demon Rahu swallowing the moon at the temple Wat Phang La in southern Thailand.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/anandajoti/10684670235/">(Anandajoti Bhikkhu/flickr)</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>Indian myths tell of an <a href="https://www.washingtonpost.com/graphics/2017/lifestyle/eclipse-myths/">immortal demon seeking revenge on Vishnu by trying to eat the sun and moon</a>. The Pomo, Indigenous people of Northern California, describe <a href="https://www.exploratorium.edu/eclipse/eclipse-stories-from-around-the-world">a huge angry bear trying to eat the sun</a>. In other mythologies, eclipses were thought to be heavenly forces removing our source of warmth and life.</p>
<p>Beliefs about eclipses motivated ancient Greek astronomers to create the <a href="https://doi.org/10.1371/journal.pone.0103275">antikythera mechanism</a>, a complex analog computer that predicted the timing of future eclipses with a precision of 30 minutes. These predictions were critical for Greek society as a solar eclipse could mean an upcoming death of the king, requiring the appointment of a pseudo-emperor to be killed instead.</p>
<p>Our reactions to eclipses have evolved, driving us to better understand the solar system and the universe at large. </p>
<p>During the eclipse on Aug. 18, 1868, astronomers Norman Lockyer and Pierre Janssen each studied the light from the solar corona to <a href="https://doi.org/10.1007/978-1-4614-5363-5">discover a new chemical element</a>. This chemical element was named helium, after the Greek word for the sun. </p>
<p>On May 29, 1919, Frank Watson Dyson and Arthur Stanley Eddington studied the <a href="https://doi.org/10.1098/rsta.1920.0009">bent path of starlight</a> during a total solar eclipse for the first experimental “<a href="https://timesmachine.nytimes.com/timesmachine/1919/11/10/118180487.pdf">triumph of Einstein’s theory</a>” of general relativity.</p>
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<a href="https://images.theconversation.com/files/580945/original/file-20240311-20-25sylo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="ancient greenish square fragments" src="https://images.theconversation.com/files/580945/original/file-20240311-20-25sylo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/580945/original/file-20240311-20-25sylo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/580945/original/file-20240311-20-25sylo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/580945/original/file-20240311-20-25sylo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/580945/original/file-20240311-20-25sylo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/580945/original/file-20240311-20-25sylo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/580945/original/file-20240311-20-25sylo.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">Fragments of an antikythera mechanism on display at a museum in Athens, Greece.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
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<h2>Eclipse experiences</h2>
<p>Unlike many other cosmic events, such as meteor showers or comets, which require expensive telescopes or <a href="https://darksky.org/what-we-do/international-dark-sky-places/">dark sky places</a>, eclipses are a barrier-free celestial event. To safely enjoy the eclipse, one simply needs eclipse viewing glasses or <a href="https://www.jpl.nasa.gov/edu/learn/project/how-to-make-a-pinhole-camera/">a cardboard box</a>. </p>
<p>Many universities across Canada are using the opportunity of the total solar eclipse to engage with people to safely experience this astronomical phenomenon. For example, Queen’s University in Kingston, Canada is making <a href="https://www.queensu.ca/physics/2024-total-solar-eclipse/eclipse-glasses">120,000 eclipse glasses available</a> to make safe eclipse viewing possible for anyone.</p>
<p>In the spirit of education, hundreds of <a href="https://astrosociety.org/education-outreach/amateur-astronomers/eclipse-ambassadors/program.html">eclipse ambassadors</a> are heading to schools to engage with students about having a profound and safe experience during the eclipse. These ambassadors lead workshops on building inexpensive pinhole cameras to project the sun during the eclipse, explaining unique features that can be seen during eclipses, such as <a href="https://science.nasa.gov/resource/baileys-beads/">Bailey’s beads</a> and the <a href="https://www.nasa.gov/image-article/diamond-ring-effect/">diamond ring effect</a>, and helping everyone appreciate the vastness of the solar system.</p>
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<a href="https://images.theconversation.com/files/580952/original/file-20240311-20-8t2snr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a black circle surrounded with a ring of light that is thicker in the lower righthand quadrant" src="https://images.theconversation.com/files/580952/original/file-20240311-20-8t2snr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/580952/original/file-20240311-20-8t2snr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=389&fit=crop&dpr=1 600w, https://images.theconversation.com/files/580952/original/file-20240311-20-8t2snr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=389&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/580952/original/file-20240311-20-8t2snr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=389&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/580952/original/file-20240311-20-8t2snr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=489&fit=crop&dpr=1 754w, https://images.theconversation.com/files/580952/original/file-20240311-20-8t2snr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=489&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/580952/original/file-20240311-20-8t2snr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=489&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">The Baily’s Beads effect occurs when gaps in the moon’s rugged terrain allow sunlight to pass through in some places just before the total phase of the eclipse.</span>
<span class="attribution"><a class="source" href="https://science.nasa.gov/resource/baileys-beads/">(Aubrey Gemignani/NASA)</a></span>
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<p>These efforts demonstrate the universal value of science, and promote science engagement beyond classrooms and institutions.</p>
<p>Not only is the upcoming eclipse being leveraged as an opportunity to inspire the next generation of scientists, but it is also being used for the advancement of scientific knowledge. Unlike the experiments of Dyson, Eddington and Lockyer that were limited to the academy, today’s institutions are mobilizing the public to conduct citizen science experiments. </p>
<p>Initiated by NASA, the <a href="https://eclipsemegamovie.org/goals">Eclipse Megamovie project</a> will use photos taken during totality of the solar eclipse to study the solar corona. In 2017, photos collected during the total eclipse helped researchers identify a plasma plume in the solar corona. The 2024 eclipse will help researchers study this plume in greater detail. </p>
<p>Anyone with a DSLR camera and a tripod can submit a picture of the total solar eclipse to the Eclipse Megamovie project. The public data collected for the 2024 eclipse will far exceed what could be accomplished by any one experiment or location.</p>
<p>April’s total solar eclipse, and others to come, will remind people that science is exciting and inspiring, and that scientific expertise is of profound universal value. Such a celestial coincidence is an opportunity to engage with local communities and discuss the origin and mechanics of our solar system, all while including the public in scientific discovery through crowd-sourcing images of their experience. </p>
<p>All that’s left is to hope for clear skies and marvel once more at the cosmos.</p><img src="https://counter.theconversation.com/content/222707/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nikhil Arora receives funding from the National Sciences and Engineering Research Council of Canada.</span></em></p><p class="fine-print"><em><span>Mark Richardson is based at the Arthur B. McDonald Canadian Astroparticle Physics Research Institute, who has received funding from the Canada First Research Excellence Fund. </span></em></p>Eclipses have inspired myths, predictions and scientific discoveries. The total solar eclipse occurring on April 8 provides a once-in-a-lifetime opportunity to engage with science and the cosmos.Nikhil Arora, Postdoctoral fellow, Physics, Engineering Physics & Astronomy, Queen's University, OntarioMark Richardson, Manager for Education and Public Outreach, Adjunct Professor of Physics and Astronomy, Queen's University, OntarioLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2241132024-03-12T18:55:13Z2024-03-12T18:55:13ZSolar eclipses result from a fantastic celestial coincidence of scale and distance<figure><img src="https://images.theconversation.com/files/580531/original/file-20240307-28-al4bnq.jpg?ixlib=rb-1.1.0&rect=23%2C15%2C5247%2C3690&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Solar eclipses happen because of a few factors, including the Moon's size and distance from the Sun. </span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/EclipseKentucky/8b202fc6981149ebb1c59158d49e348d/photo?Query=eclipse&mediaType=photo&sortBy=&dateRange=Anytime&totalCount=478&digitizationType=Digitized&currentItemNo=7&vs=true&vs=true">AP Photo/Timothy D. Easley</a></span></figcaption></figure><p>On April 8, 2024, millions across the U.S. will have the once-in-a-lifetime chance to view a total solar eclipse. <a href="https://science.nasa.gov/eclipses/future-eclipses/eclipse-2024/where-when/">Cities including</a> Austin, Texas; Buffalo, New York; and Cleveland, Ohio, will have a direct view of this rare cosmic event that lasts for just a few hours.</p>
<p>While <a href="https://theconversation.com/astro-tourism-chasing-eclipses-meteor-showers-and-elusive-dark-skies-from-earth-207969">you can see many astronomical events</a>, such as <a href="https://theconversation.com/comets-101-everything-you-need-to-know-about-the-snow-cones-of-space-213342">comets</a> and meteor showers, from anywhere on Earth, eclipses are different. You need to travel to what’s called the <a href="https://theconversation.com/when-the-sun-goes-dark-5-questions-answered-about-the-solar-eclipse-81308">path of totality</a> to experience the full eclipse. Only certain places get an eclipse’s full show, and that’s because of scale. </p>
<p>The relatively small <a href="https://www.space.com/18135-how-big-is-the-moon.html">size of the Moon</a> and its shadow make eclipses truly once-in-a-lifetime opportunities. On average, total solar eclipses are visible somewhere on Earth once every few years. But from any one location on Earth, <a href="https://eclipse.gsfc.nasa.gov/SEcirc/SEcirc.html">it is roughly 375 years</a> between solar eclipses.</p>
<p><a href="https://science.psu.edu/astro/people/cxp137">I’m an astronomer</a>, but I have never seen a total solar eclipse, so I plan to drive to Erie, Pennsylvania, in the path of totality, for this one. This is one of the <a href="https://eclipse.gsfc.nasa.gov/SEmap/SEmapNA/TSENorAm2051.gif">few chances I have</a> to see a total eclipse without making a much more expensive <a href="https://theconversation.com/astro-tourism-chasing-eclipses-meteor-showers-and-elusive-dark-skies-from-earth-207969">trip to someplace more remote</a>. Many people have asked me why nearby eclipses are so rare, and the answer is related to the size of the Moon and its distance from the Sun.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/fmtGqOxxmEU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Those in the path of totality will have the opportunity to see a total solar eclipse this April.</span></figcaption>
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<h2>Size and scale</h2>
<p>You can observe a solar eclipse when the Moon passes in front of the Sun, blocking some or all of the Sun from view. For people on Earth to be able to see an eclipse, the Moon, while orbiting around the Earth, must lie exactly along the observer’s line of sight with the Sun. Only some observers will see an eclipse, though, because not everyone’s view of the Sun will be blocked by the Moon on the day of an eclipse. </p>
<p>The fact that solar eclipses happen at all is a bit of a numerical coincidence. It just so happens <a href="https://science.nasa.gov/sun/facts/#hds-sidebar-nav-3">that the Sun</a> is approximately 400 times <a href="https://science.nasa.gov/moon/facts/#hds-sidebar-nav-3">larger than the Moon</a> and also 400 times more distant from the Earth. </p>
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<a href="https://images.theconversation.com/files/581049/original/file-20240311-22-9ovtoi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photo showing the Earth next to the Moon. The Earth is much larger." src="https://images.theconversation.com/files/581049/original/file-20240311-22-9ovtoi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/581049/original/file-20240311-22-9ovtoi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/581049/original/file-20240311-22-9ovtoi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/581049/original/file-20240311-22-9ovtoi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/581049/original/file-20240311-22-9ovtoi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/581049/original/file-20240311-22-9ovtoi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/581049/original/file-20240311-22-9ovtoi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Earth’s size compared with the Moon. Distances not to scale.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/the-earth-and-moon-to-scale-royalty-free-image/136247709?phrase=earth+moon+size+comparison&adppopup=true">Laara Cerman/Leigh Righton/Stockbyte via Getty Images</a></span>
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<p>So, even though the Moon is much smaller <a href="https://science.nasa.gov/sun/facts/">than the Sun</a>, it is just close enough to Earth to appear the same size as the Sun when seen from Earth. </p>
<p>For example, your pinky finger is much, much smaller than the Sun, but if you hold it up at arm’s length, it appears to your eye to be large enough to block out the Sun. The Moon can do the same thing – it can block out the Sun if it’s lined up perfectly with the Sun from your point of view. </p>
<h2>Path of totality</h2>
<p>When the Earth, Moon and Sun line up perfectly, the Moon <a href="https://science.nasa.gov/solar-system/skywatching/eclipses/solar-eclipses/2024-solar-eclipse/total-solar-eclipse-2024-the-moons-moment-in-the-sun/">casts a shadow onto the Earth</a>. Since the Moon is round, its shadow is round as it lands on Earth. The only people who see the eclipse are those in the area on Earth where the shadow lands at a given moment. </p>
<p>The Moon is continuously orbiting around the Earth, so as time goes on during the eclipse, the Moon’s shadow moves over the face of the Earth. Its shadow ends up looking like a thick line that can cover hundreds of miles in length. Astronomers call that line the <a href="https://science.nasa.gov/solar-system/skywatching/eclipses/new-nasa-map-details-2023-and-2024-solar-eclipses-in-the-us/">path of totality</a>. </p>
<p>From any given location along the path of totality, an observer can see the Sun completely eclipsed for a few minutes. Then, the shadow moves away from that location and the Sun slowly becomes more and more visible. </p>
<h2>A tilted orbit</h2>
<p>Solar eclipses don’t happen every single time the Moon passes in between Earth and the Sun. If that were the case, there would be a solar eclipse every month. </p>
<p>If you could float above the Earth’s North Pole and see the Moon’s orbit from above, you would see the Moon line up with the Sun once every time it orbits around the Earth, which is approximately once per month. From this high point of view, it looks like the Moon’s shadow should land on Earth every orbit. </p>
<p>However, if you could shift your perspective to look at the Moon’s orbit from the orbital plane, you would see that the Moon’s orbit is <a href="https://moon.nasa.gov/moon-in-motion/phases-eclipses-supermoons/overview/">tilted by about 5 degrees</a> compared with Earth’s orbit around the Sun. This tilt means that sometimes the Moon is too high and its shadow passes above the Earth, and sometimes the Moon is too low and its shadow passes below the Earth. An eclipse happens only <a href="https://svs.gsfc.nasa.gov/4324/">when the Moon is positioned just right</a> and its shadow lands on the Earth. </p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/JplGhSC-eGM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">There isn’t an eclipse every time the Moon passes in front of the Sun because of the Moon’s tilted orbit around Earth.</span></figcaption>
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<p>As time goes on, the Earth and the Moon continue spinning, and <a href="https://www.youtube.com/watch?v=JplGhSC-eGM">eventually the Moon aligns with Earth’s orbit</a> around the Sun at the same moment the Moon passes between the Sun and the Earth. </p>
<p>While only certain cities are in the path of totality for this April’s eclipse, the entire U.S. is still close enough to this path that observers outside of the path of totality will see a <a href="https://nso.edu/for-public/eclipse-map-2024">partial eclipse</a>. In those locations, the Moon will appear to pass in front of part of the Sun, leaving a crescent shape of the Sun still visible at the moment of maximum eclipse.</p><img src="https://counter.theconversation.com/content/224113/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christopher Palma does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Many people will see a dazzling eclipse this April, but these events are possible only because of the sizes and precise distances between Earth, the Moon and the Sun.Christopher Palma, Teaching Professor, Department of Astronomy & Astrophysics, Penn StateLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2213812024-03-12T17:44:46Z2024-03-12T17:44:46ZTotal solar eclipses, while stunning, can damage your eyes if viewed without the right protection<figure><img src="https://images.theconversation.com/files/580528/original/file-20240307-30-bxdz7t.jpg?ixlib=rb-1.1.0&rect=47%2C6%2C4468%2C2383&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Solar eclipses don't come around often, but make sure to view these rare events with eclipse glasses to protect your vision. </span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/USEclipseSchools/0f2e25e7620440c0be042b6516d1acde/photo?Query=eclipse%20viewing&mediaType=photo&sortBy=&dateRange=Anytime&totalCount=524&digitizationType=Digitized&currentItemNo=18&vs=true&vs=true">AP Photo/Charlie Riedel</a></span></figcaption></figure><p>On April 8, 2024, and for the second time in the past decade, people in the U.S. will have an opportunity to <a href="https://science.nasa.gov/eclipses/future-eclipses/eclipse-2024/">view a total solar eclipse</a>. But to do so safely, you’ll need to <a href="https://preventblindness.org/get-ready-for-the-next-eclipse/">wear proper protection</a>, or risk eye damage.</p>
<p>Earth is the only planet in our solar system where <a href="https://theconversation.com/when-the-sun-goes-dark-5-questions-answered-about-the-solar-eclipse-81308">solar eclipses can occur</a>. During these celestial events, the Moon passes between our planet and the Sun, blocking the Sun and casting a shadow over the Earth. Total eclipses rarely happen multiple times in the same region of a country during one’s lifetime. </p>
<p>The path of totality for <a href="https://science.nasa.gov/eclipses/">this spring’s eclipse</a>, where you can view the total eclipse, will extend over a 100-mile path that crosses through Mexico, Texas, New England and eastern Canada.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/fmtGqOxxmEU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Those in the path of totality will have the opportunity to see a total solar eclipse this April.</span></figcaption>
</figure>
<p>As excitement for the celestial show grows across the country, <a href="https://www.forbes.com/sites/jamiecartereurope/2024/03/09/11-ways-to-find-your-last-minute-hotel-for-the-total-solar-eclipse---but-be-quick/?sh=415b5585f4e2">hotels in the path of totality</a> have been booked up by eclipse enthusiasts. Museums and schools have <a href="https://solarsystem.nasa.gov/embeddable-eclipse-events/">planned viewing events</a>, and researchers have developed technology for the <a href="https://astrolab.fas.harvard.edu/LightSound.html">visually impaired and those with hearing loss</a> so more people have the opportunity to experience the eclipse.</p>
<p>Seeing an eclipse is a rare and special opportunity, but <a href="https://directory.hsc.wvu.edu/Profile/28506">as an ophthalmologist</a>, I know that looking directly at the Sun, even for a few moments, can severely damage your eyes. With a few easy precautions, eclipse viewers can protect themselves from severe and irreparable eye damage and vision loss.</p>
<h2>Safe eclipse viewing</h2>
<p>This year’s eclipse will unfold over a 75-minute period, from the moment the Moon starts to partially block the Sun until it completely moves away from it again. </p>
<p>During the partial eclipse period, when the Moon is partly blocking the Sun, you should never look directly at the Sun nor through binoculars, <a href="https://www.masterclass.com/articles/how-to-photograph-a-solar-eclipse">cameras</a> or <a href="https://www.space.com/how-to-photograph-a-solar-eclipse-with-a-smartphone">cellphones</a>. Sunglasses, photographic filters, exposed color film and welding glasses will dim the sunlight, but these items do not prevent <a href="https://www.aao.org/eye-health/tips-prevention/solar-eclipse-eye-safety">eye damage from the Sun’s very intense light rays</a>. </p>
<p>Only <a href="https://preventblindness.org/solar-eclipse-glasses/">solar eclipse glasses</a> with filters designed specifically for observing the partial eclipse are safe to use. They are easily available <a href="https://www.cnn.com/cnn-underscored/outdoors/best-solar-eclipse-glasses?cid=ios_app">from a variety of sources</a>, and you can wear them by themselves or over your glasses or contact lenses. </p>
<p>Keep in mind that these safety filters will permit you to view only the eclipse, as they blacken out everything around you but the Sun itself. Before purchasing a pair, make sure your eclipse glasses are approved by the <a href="https://eclipse.aas.org/eye-safety/iso-certification">ISO 12312-2 international standard</a>.</p>
<p>Only during its <a href="https://eclipse.gsfc.nasa.gov/SEhelp/SEglossary.html">period of totality</a>, the time when the Sun is fully behind the Moon, is it safe to remove your filtered glasses – and then only with caution.</p>
<p>This year, totality will last an unusually long <a href="https://science.nasa.gov/eclipses/future-eclipses/eclipse-2024/">four and a half minutes</a>. If you leave your eclipse glasses on, you will miss seeing the Sun’s bright ring, or corona, behind the Moon. But then, as the Moon moves on, the sky will brighten and you’ll need to put the eclipse glasses back on.</p>
<h2>Eyes and light</h2>
<p>While the pupils of our eyes naturally constrict to limit bright light, and our eyes have pigments to absorb light, direct sunlight overwhelms these functions. Even viewing the Sun for a few brief moments <a href="https://theconversation.com/turn-around-bright-eyes-heres-how-to-see-the-eclipse-and-protect-your-vision-203571">can cause permanent vision loss</a>. </p>
<p>The Sun emits intense <a href="https://www.britannica.com/science/sunlight-solar-radiation">ultraviolet and infrared light</a>, which, while not visible to the human eye, can burn sensitive ocular tissues, such as the cornea and retina.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/581353/original/file-20240312-24-e55u1i.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram of an eye as viewed from the side." src="https://images.theconversation.com/files/581353/original/file-20240312-24-e55u1i.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/581353/original/file-20240312-24-e55u1i.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=486&fit=crop&dpr=1 600w, https://images.theconversation.com/files/581353/original/file-20240312-24-e55u1i.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=486&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/581353/original/file-20240312-24-e55u1i.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=486&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/581353/original/file-20240312-24-e55u1i.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=611&fit=crop&dpr=1 754w, https://images.theconversation.com/files/581353/original/file-20240312-24-e55u1i.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=611&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/581353/original/file-20240312-24-e55u1i.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=611&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 cornea is the clear front surface of the eye, which lets light in. The retina is the inner lining of the back part of the eye, which sends signals to your brain, allowing you to see.</span>
<span class="attribution"><a class="source" href="https://aapos.org/glossary/how-to-safely-view-a-solar-eclipse">American Association for Pediatric Ophthalmology and Strabismus</a></span>
</figcaption>
</figure>
<p>Corneal damage from sunlight, called <a href="https://www.mayoclinic.org/diseases-conditions/actinic-keratosis/symptoms-causes/syc-20354969">solar keratosis</a>, can blur vision and be quite painful. While the cornea can heal itself, it may require several days to get better and lead to lost time at work or school. </p>
<p>Retinal damage, called <a href="https://www.health.wa.gov.au/Articles/S_T/Solar-retinopathy">solar retinopathy</a>, occurs inside the eye. While it isn’t painful, it can be more severe than corneal damage and can dramatically impair vision. Solar retinopathy symptoms include a blind spot in one’s central vision, visual distortions and altered color vision. </p>
<p>In mild cases, these symptoms may go away, but in more severe cases, and even with treatment, <a href="https://aapos.org/glossary/how-to-safely-view-a-solar-eclipse">they may become permanent</a>. </p>
<p>To both enjoy the eclipse and prevent eye damage, make sure you and your loved ones all view the event with strict proper precautions.</p><img src="https://counter.theconversation.com/content/221381/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Geoffrey Bradford does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Now’s the time to get your hands on a pair of eclipse glasses in preparation for April’s display of celestial wonder.Geoffrey Bradford, Professor of Pediatrics and Ophthalmology, West Virginia UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2227092024-03-11T20:26:45Z2024-03-11T20:26:45ZArcheoastronomy uses the rare times and places of previous total solar eclipses to help us measure history<figure><img src="https://images.theconversation.com/files/580911/original/file-20240311-28-ygi764.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1280%2C1280&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A photograph of the 2017 total solar eclipse, taken at the Oregon State Fair Grounds, Salem, Ore.</span> <span class="attribution"><span class="source">(Dominic Hart/NASA)</span></span></figcaption></figure><p>In 648 BCE, the Greek poet Archilochus wrote that, “nothing can be surprising any more or impossible or miraculous, now that Zeus, father of the Olympians has <a href="https://articles.adsabs.harvard.edu/pdf/2020JAHH...23...47S">made night out of noonday</a>, hiding the light of the gleaming Sun.”</p>
<p>Total solar eclipses have fascinated and terrified people for centuries. Today, we know that total solar eclipses — like the <a href="https://theconversation.com/on-april-8-2024-parts-of-ontario-quebec-the-maritimes-and-newfoundland-will-see-a-total-eclipse-of-the-sun-heres-how-to-get-ready-for-it-203382">upcoming eclipse on April 8</a> — are caused by a cosmic coincidence when the moon comes between the Earth and the sun, momentarily blocking the sun from view. But in ancient times, the cause was unknown.</p>
<p>Nevertheless, the peoples of those eras took note. From all ends of the Earth, stories abound of day turning to night or <a href="https://eclipse2017.nasa.gov/eclipse-history">the sun being consumed</a>, and these records are opening up a new branch of study.</p>
<p><a href="https://www.jstor.org/stable/20170165">Astroarcheology</a> — also called archeoastronomy — uses astronomical records to help date key moments or events in history. Of all astronomical phenomena, total solar eclipses are among the best measuring sticks because they are only visible at a certain time and place. </p>
<p>Total solar eclipses are rare enough that a given spot on Earth is only likely to see <a href="https://articles.adsabs.harvard.edu/pdf/1982JBAA...92..124M">one every 375 years (on average)</a>. And when an eclipse does happen, it only appears as total to those who are <a href="https://eclipsewise.com/solar/SEatlas/SEatlas.html">along a narrow path on Earth</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/580844/original/file-20240310-26-te2a9p.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="(drawing of a solar eclipse represented by a black circle surrounded by a white aura on a black background)" src="https://images.theconversation.com/files/580844/original/file-20240310-26-te2a9p.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/580844/original/file-20240310-26-te2a9p.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=464&fit=crop&dpr=1 600w, https://images.theconversation.com/files/580844/original/file-20240310-26-te2a9p.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=464&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/580844/original/file-20240310-26-te2a9p.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=464&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/580844/original/file-20240310-26-te2a9p.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=583&fit=crop&dpr=1 754w, https://images.theconversation.com/files/580844/original/file-20240310-26-te2a9p.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=583&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/580844/original/file-20240310-26-te2a9p.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=583&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An illustration of the solar eclipse that occurred on Jan. 22, 1898 in India.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Solar_eclipse_of_January_22,_1898">(Edward Walter Maunder/British Astronomical Association)</a></span>
</figcaption>
</figure>
<h2>Identifying years</h2>
<p>This combination of rare time and place helps researchers narrow down the exact date ancient peoples viewed a recorded eclipse. Additional clues such as the time of day the eclipse occurred (morning, noon or evening), time of year (season) or the presence of bright planets can also help identify the exact eclipse.</p>
<p>For example, a record of total solar eclipse occurring near dawn in ancient Chinese texts pertaining to King Yi helped <a href="https://articles.adsabs.harvard.edu/pdf/2003JAHH....6...53L">identify the year his reign began</a>.</p>
<p>One of the oldest recorded eclipses is on a clay tablet from the city of <a href="https://www.britannica.com/place/Ugarit">Ugarit, in modern-day Syria</a>. The city was overthrown after the eclipse, making the tablet one of the last things written down by someone from that city. The inscription on the tablet reads: “… day of the new moon in ḫiyaru the Sun went down, its gate-keeper was [Rashap].”</p>
<p>The word ḫiyaru refers to a time of year around February/March, and Rashap is likely a planet. Armed with this information and knowledge that the city disappeared in the Bronze Age, researchers dated the tablet and eclipse to March 5, 1222 BCE, over 3,000 years ago, with the planet Mars <a href="https://doi.org/10.1038/338238a0">visible near to the eclipsed sun</a>. Thanks to this eclipse, we know that Ugarit fell after March 5, 1222 BCE. </p>
<p>Records like these help researchers identify precise dates in the ancient world.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/580919/original/file-20240311-17800-m97ekg.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="an illustration of text above a photograph of a grey clay tablet" src="https://images.theconversation.com/files/580919/original/file-20240311-17800-m97ekg.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/580919/original/file-20240311-17800-m97ekg.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=689&fit=crop&dpr=1 600w, https://images.theconversation.com/files/580919/original/file-20240311-17800-m97ekg.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=689&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/580919/original/file-20240311-17800-m97ekg.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=689&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/580919/original/file-20240311-17800-m97ekg.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=866&fit=crop&dpr=1 754w, https://images.theconversation.com/files/580919/original/file-20240311-17800-m97ekg.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=866&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/580919/original/file-20240311-17800-m97ekg.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=866&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Photograph and illustration of the clay tablet KTU 1.78 from Ugarit, in modern-day Syria, which mentions a total solar eclipse.</span>
<span class="attribution"><span class="source">(Dietrich and Loretz/University of Chicago Library)</span></span>
</figcaption>
</figure>
<h2>Changing predictions</h2>
<p>Precisely predicting future eclipses, or plotting the paths of historical eclipses, requires knowing the positions of the sun, moon and Earth. Computers can track the motions of each, but the challenge here is that these motions are not constant. As the moon causes tides in Earth’s oceans, the process also causes the moon to slowly drift away from the Earth and <a href="https://www.scientificamerican.com/article/earth-rotation-summer-solstice/">the length of day on Earth to slowly increase</a>. </p>
<p>Essentially, the length of a day on Earth is getting longer by roughly 18 microseconds every year, <a href="http://dx.doi.org/10.1098/rspa.2016.0404">or one second every 55,000 years</a>. After hundreds or thousands of years, that fraction of a second per day adds up to several hours.</p>
<p>The change in Earth’s day also affects dating historical eclipses — if the difference in the length of day is not corrected for, calculations may be inaccurate by thousands of kilometers. As such, when using eclipses to date historical events a correction must be applied; uncertainties in the correction can make <a href="https://doi.org/10.1093/pasj/56.1.215">ancient eclipse identifications</a> harder to pin down in the absence of <a href="https://www.jstor.org/stable/178278">additional information</a> to help <a href="https://articles.adsabs.harvard.edu/pdf/1995QJRAS..36..397Z">narrow down the possibilities</a>. </p>
<h2>Measuring changing day-lengths</h2>
<p>For those solar eclipses that are well established, they open a window into tracking Earth’s length-of-day across the centuries. By timing eclipses over the last 2,000 years, researchers have mapped out the length of Earth’s day over that same span. The value of 18 microseconds per year is an average, but sometimes the Earth slows down a bit more and sometimes a bit less. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/580922/original/file-20240311-139405-bs1pct.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a graph showing day lengths over time" src="https://images.theconversation.com/files/580922/original/file-20240311-139405-bs1pct.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/580922/original/file-20240311-139405-bs1pct.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=413&fit=crop&dpr=1 600w, https://images.theconversation.com/files/580922/original/file-20240311-139405-bs1pct.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=413&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/580922/original/file-20240311-139405-bs1pct.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=413&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/580922/original/file-20240311-139405-bs1pct.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=518&fit=crop&dpr=1 754w, https://images.theconversation.com/files/580922/original/file-20240311-139405-bs1pct.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=518&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/580922/original/file-20240311-139405-bs1pct.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=518&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Change in length of day (lod) for Earth in milliseconds (0.001 s) as measured from eclipse records (black line). The red line shows the average change over 2,000 years, while the grey line shows what we would expect from tidal forces between the Earth and moon only. The green dashed line shows a model fit to the data in black.</span>
<span class="attribution"><a class="source" href="http://dx.doi.org/10.1098/rspa.2016.0404">(F.R. Stephenson, L.V. Morrison and C.Y. Hohenkerk)</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Tides alone can’t explain this pattern — there is something more going on between the moon and the Earth, and the cause is still unknown. This mystery, however, can be explored thanks to solar eclipses. </p>
<p>We can measure a change in length of a day on Earth with instruments now, but we wouldn’t be able to capture that change hundreds or thousands of years back in time without a precise measuring stick and records of eclipses over millennia and across the world. Total solar eclipses allow us to peer into not only our own history, but the history of the Earth itself.</p><img src="https://counter.theconversation.com/content/222709/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sarah Sadavoy receives funding from the National Sciences and Engineering Research Council of Canada (NSERC). </span></em></p>Mentions of total solar eclipses in ancient history help researchers pinpoint precise dates of notable events.Sarah Sadavoy, Assistant Professor, Physics, Engineering Physics & Astronomy, Queen's University, OntarioLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2208242024-03-08T14:35:38Z2024-03-08T14:35:38ZApril’s eclipse will mean interruptions in solar power generation, which could strain electrical grids<figure><img src="https://images.theconversation.com/files/573902/original/file-20240206-16-om8k0f.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3994%2C2658&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Solar panels in Brazil. </span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/7551d26521224cbf94340e255374a7a7?ext=true">AP Photo/Bruna Prado</a></span></figcaption></figure><p>During the most recent total solar eclipse visible in the U.S., on Aug. 21, 2017, the skies darkened as the Moon crossed in front of the Sun. It blocked out all sunlight – except for that from a golden ring visible around the Moon’s shape, called the corona. Not surprisingly, solar power generation across North America plummeted for several hours, from the first moment the Moon began to obscure the Sun to when the Sun’s disk was clear again. </p>
<p>On April 8, 2024, another <a href="https://theconversation.com/when-the-sun-goes-dark-5-questions-answered-about-the-solar-eclipse-81308">total solar eclipse</a> will track across the U.S., causing perhaps an even greater loss of solar power generation. Although this will be the second total solar eclipse visible in the U.S. in under seven years, these events are a rare occurrence. Nevertheless, they present a unique challenge to power grid operators.</p>
<p><a href="https://dornsife.usc.edu/profile/vahe-peroomian/">I am a space scientist</a> with a passion for teaching physics and astronomy. Though I have seen many partial eclipses of the Sun, I have yet to witness a total solar eclipse. My road trip to Bryce Canyon National Park in Utah in October 2023 to see the “ring of fire” <a href="https://theconversation.com/explainer-what-is-a-solar-eclipse-33019">annular solar eclipse</a> was unforgettable, and April 8 will surely find me handing out <a href="https://theconversation.com/turn-around-bright-eyes-heres-how-to-see-the-eclipse-and-protect-your-vision-203571">eclipse glasses</a> once again.</p>
<h2>When the Moon’s shadow blocks the Sun</h2>
<p>During <a href="https://theconversation.com/explainer-what-is-a-solar-eclipse-33019">a solar eclipse</a>, the Moon partially or completely blocks the view of the Sun. Since the Moon is nearly 400 times smaller than the Sun and nearly <a href="https://www.universetoday.com/17109/the-sun-and-the-moon/">400 times closer</a>, the <a href="https://www.forbes.com/sites/startswithabang/2017/02/08/the-strangest-eclipse-fact-of-all-the-moons-shadow-isnt-a-circle/?sh=be76f8c17bd3">Moon’s shadow</a>, visible from Earth, tapers to a width of <a href="https://cmase.uark.edu/_resources/pdf/nasa/NASAConnect/pathoftotality.pdf">70 to 100 miles</a> (112 to 161 kilometers).</p>
<p>Within this region, called the path of totality, observers see a total solar eclipse. Observers close to but outside this path witness a partial eclipse of the Sun, where the Moon covers a fraction of the Sun’s disk. </p>
<p>During the April 8, 2024, total solar eclipse, the <a href="https://science.nasa.gov/eclipses/future-eclipses/eclipse-2024/where-when/">path of totality</a> in the continental U.S. will extend from Texas in the south to Maine in the northeast. Elsewhere in the U.S., Miami will see a partial eclipse in which a maximum of 46% of the Sun’s disk is obscured. In Seattle, far from the path of totality, the Moon will cover only a maximum of <a href="https://www.timeanddate.com/eclipse/map/2024-april-8">20% of the Sun</a>. In southern Texas, where the path of totality first crosses into the U.S., the eclipse will last just under three hours, with totality a mere 4 minutes and 27 seconds. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/sOpYoO_SK7o?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The path of the 2024 solar eclipse.</span></figcaption>
</figure>
<h2>Increasing reliance on solar power</h2>
<p>The worldwide trend toward renewable energy has seen a significant increase in solar, or photovoltaic, power generation in the last decade. Solar power generation capacity is set to <a href="https://www.iea.org/data-and-statistics/data-tools/renewable-energy-progress-tracker">double worldwide</a> between 2022 and 2028, and the U.S. now has the capacity to generate <a href="https://ember-climate.org/data-catalogue/yearly-electricity-data/">three times more solar energy</a> than at the time of the 2017 total solar eclipse.</p>
<p>The most obvious obstacle to solar power generation is cloud cover. On a cloudy day, the energy produced by solar panels drops to <a href="https://www.forbes.com/home-improvement/solar/solar-panels-cloudy-days-night/">10% to 25%</a> of its output on a sunny day. </p>
<p>The North American power transmission grid is divided into <a href="https://www.nerc.com/AboutNERC/keyplayers/Pages/default.aspx">six major regions</a> and <a href="https://alternativeenergy.procon.org/questions/what-is-the-electricity-grid/">more than 150</a> local and regional subgrids. Electrical system operators in each local grid continuously balance the amount of electricity production with the “load,” or the demand for electricity by consumers. </p>
<p>System operators can tap into energy from <a href="https://science.howstuffworks.com/environmental/energy/power.htm">various power generation mechanisms</a> like solar, wind, hydroelectric, natural gas and coal. Local grids can also import and export electricity to and from their grid as needed.</p>
<p>System operators have accurate models for the amount of solar power generated across the U.S. on a daily basis, and these models account for the parts of the continental U.S. that may have cloudy skies. By pairing solar power generation with battery storage, they can access electricity from solar even when the Sun isn’t shining – on cloudy days or at night. </p>
<p>To plan for an eclipse, electrical system operators need to figure out how much the energy production will drop and how much power people will draw from the reserves. On the day of the 2017 total solar eclipse, for example, solar power generation in the U.S. <a href="https://www.nrel.gov/docs/fy18osti/71147.pdf">dropped 25%</a> below average. </p>
<p>Because solar power production falls quickly during the eclipse’s peak, grid operators may need to tap into reserves at a rate that may strain the <a href="https://www.osha.gov/etools/electric-power/illustrated-glossary/transmission-lines">electrical transmission lines</a>. To try to keep things running smoothly, grid operators will rely on local reserves and minimize power transfer <a href="https://www.nrel.gov/docs/fy18osti/71147.pdf">between grids</a> during the event. This should lessen the burden on transmission lines in local grids and prevent temporary blackouts. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/573903/original/file-20240206-28-khlo8k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Electrical towers and power lines shown against a sunset." src="https://images.theconversation.com/files/573903/original/file-20240206-28-khlo8k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/573903/original/file-20240206-28-khlo8k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/573903/original/file-20240206-28-khlo8k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/573903/original/file-20240206-28-khlo8k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/573903/original/file-20240206-28-khlo8k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/573903/original/file-20240206-28-khlo8k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/573903/original/file-20240206-28-khlo8k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Solar eclipses can stress the power grid.</span>
<span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/BidenInfrastructure/9a4ee5858ac74db78eb7d96b1961c275/photo?Query=power%20grid&mediaType=photo&sortBy=&dateRange=Anytime&totalCount=226&digitizationType=Digitized&currentItemNo=17&vs=true&vs=true">AP Photo/Matt Rourke</a></span>
</figcaption>
</figure>
<h2>Renewable energy during eclipses</h2>
<p>Solar isn’t the only type of renewable energy generation that goes down during an eclipse. Since it’s not as sunny, temperatures along the path of the eclipse fall by as much as <a href="https://eclipse2017.nasa.gov/temperature-change-during-totality">10 degrees Fahrenheit</a> (5.5 degrees Celsius). Lower temperatures lead to <a href="https://doi.org/10.1093/astrogeo/atx135">slower wind speeds</a> and less wind power generation. </p>
<p>During the August 2017 eclipse, the loss of renewable power generation added up to nearly <a href="https://www.nrel.gov/docs/fy18osti/71147.pdf">6 gigawatts</a>. That’s equivalent to the energy usage of <a href="https://www.energy.gov/eere/articles/how-much-power-1-gigawatt">600 million LED lightbulbs</a> or <a href="https://www.cnet.com/home/energy-and-utilities/gigawatt-the-solar-energy-term-you-should-know-about/">4.5 million homes</a>. </p>
<p>Grid operators compensated by planning ahead and increasing power generation at <a href="https://www.nrel.gov/docs/fy18osti/71147.pdf">natural gas and coal-powered plants</a>, which don’t depend on sunlight. </p>
<p>Over the duration of the eclipse, this increase in nonrenewable energy use led to approximately <a href="https://www.eia.gov/tools/faqs/faq.php?id=74&t=11">10 million pounds</a> of extra carbon dioxide emissions. That’s about the annual carbon dioxide emissions of 1,000 cars.</p>
<p>On April 8, <a href="https://theconversation.com/astro-tourism-chasing-eclipses-meteor-showers-and-elusive-dark-skies-from-earth-207969">eyes across the U.S. will turn upward</a> to catch a glimpse of the eclipsed Sun.</p>
<p>Thanks to the vigilance of electric grid operators, the lights should stay on, and observers won’t have to worry about anything but the stunning show in the sky.</p><img src="https://counter.theconversation.com/content/220824/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Vahe Peroomian has, in the past, received basic research funding from NASA and the National Science Foundation.</span></em></p>When the Moon blocks the Sun during an eclipse, utility suppliers have to pull power from the grid to make up for gaps in solar energy.Vahe Peroomian, Professor of Physics and Astronomy, USC Dornsife College of Letters, Arts and SciencesLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2079692023-07-05T12:22:40Z2023-07-05T12:22:40ZAstro-tourism − chasing eclipses, meteor showers and elusive dark skies from Earth<figure><img src="https://images.theconversation.com/files/534389/original/file-20230627-23-gjawwc.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2460%2C1215&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">On April 8, 2024, much of the eastern United States will fall in the path of a total solar eclipse, like the one pictured. </span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/total-solar-eclipse-and-monument-valley-at-sunrise-royalty-free-image/128311871?phrase=eclipse">Diane Miller/The Image Bank via Getty images</a></span></figcaption></figure><p>For years, small groups of astronomy enthusiasts have traveled the globe chasing the rare solar eclipse. They have embarked on <a href="https://pbcruise.com/news/3989">cruises</a> to the middle of the ocean, taken <a href="https://www.livescience.com/60229-how-to-calculate-where-eclipse-airplane-intersect.html">flights</a> into the eclipse’s path and even traveled to <a href="https://www.space.com/total-solar-eclipse-2021-over-antarctica-video">Antarctica</a>. </p>
<p>In August 2017, millions across the U.S. witnessed a <a href="https://www.npr.org/2017/08/27/546109041/eclipse-2017-one-nation-under-the-sun">total solar eclipse</a> visible from Oregon to South Carolina, with a partial eclipse visible to the rest of the continental U.S. On April 8, 2024, millions of Americans will once again be in the path of <a href="https://www.greatamericaneclipse.com">a total solar eclipse</a>, this one’s path extending from Mexico to eastern Canada.</p>
<p>The April 2024 eclipse’s path of totality will <a href="https://science.nasa.gov/eclipses/future-eclipses/eclipse-2024/where-when/">cross a number of U.S. cities</a>, including Austin and Dallas in Texas, Indianapolis in Indiana, Cleveland and Dayton in Ohio, Erie in Pennsylvania, and Buffalo and Rochester in New York. The eclipse will begin in Texas around 2:30 Eastern time and end in Maine around 4:30 Eastern.</p>
<p>But astro-tourism – traveling to national parks, observatories or other natural, dark-sky locations to view astronomical events – isn’t limited to chasing eclipses.</p>
<p>According to a recent study, <a href="https://www.nationalgeographic.com/science/article/milky-way-space-science">80% of Americans</a> and <a href="https://www.astronomy.com/science/one-third-of-humanity-cant-see-the-milky-way/">one-third of the planet’s population</a> can no longer see the Milky Way from their homes <a href="https://cires.colorado.edu/artificial-sky">because of light pollution</a>. As a consequence, most people have to travel to witness meteor showers and other common astronomical events. </p>
<p><a href="https://dornsife.usc.edu/profile/vahe-peroomian/">I am a space scientist</a> with a passion for teaching physics and astronomy and photographing the night sky. Every summer I spend several nights backpacking in the Sierra Nevada of California, where the skies are sufficiently dark to allow the Milky Way to be seen with the naked eye. My son and I also like to take road trips – often along U.S. Route 395, the Eastern Sierra Scenic Byway – that coincide with eclipses and meteor showers.</p>
<figure class="align-center ">
<img alt="A lake under snow-speckled mountains, with lots of stars visible in the night sky." src="https://images.theconversation.com/files/533047/original/file-20230621-27-fg3o9f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/533047/original/file-20230621-27-fg3o9f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=408&fit=crop&dpr=1 600w, https://images.theconversation.com/files/533047/original/file-20230621-27-fg3o9f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=408&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/533047/original/file-20230621-27-fg3o9f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=408&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/533047/original/file-20230621-27-fg3o9f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=513&fit=crop&dpr=1 754w, https://images.theconversation.com/files/533047/original/file-20230621-27-fg3o9f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=513&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/533047/original/file-20230621-27-fg3o9f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=513&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Natural locations, removed from city light, can be great places for astro-tourism.</span>
<span class="attribution"><span class="source">Vahe Peroomian</span></span>
</figcaption>
</figure>
<h2>Can’t-miss astronomical events</h2>
<p>There are two types of eclipses. <a href="https://moon.nasa.gov/moon-in-motion/phases-eclipses-supermoons/eclipses/">Lunar eclipses</a> occur when the full moon passes through Earth’s shadow. <a href="https://solarsystem.nasa.gov/eclipses/home/">Solar eclipses</a> occur when the new moon briefly blocks the Sun. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/534606/original/file-20230628-19-7l230z.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram showing the Moon's orbit around the sun, with the Moon's two orbital nodes marked, and its orbital plane's 5 degree tilt noted." src="https://images.theconversation.com/files/534606/original/file-20230628-19-7l230z.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/534606/original/file-20230628-19-7l230z.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=302&fit=crop&dpr=1 600w, https://images.theconversation.com/files/534606/original/file-20230628-19-7l230z.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=302&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/534606/original/file-20230628-19-7l230z.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=302&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/534606/original/file-20230628-19-7l230z.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=379&fit=crop&dpr=1 754w, https://images.theconversation.com/files/534606/original/file-20230628-19-7l230z.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=379&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/534606/original/file-20230628-19-7l230z.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=379&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Eclipses may occur one after another if the Moon’s nodes align with the Sun.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Eclipse_vs_new_or_full_moons,_annotated.svg">Nela (nyabla.net)/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>There are three types of solar eclipses. During a total eclipse, the Moon completely covers the Sun, with totality lasting as long as seven minutes. During totality, those in the path of the eclipse will see the Sun’s <a href="https://spaceplace.nasa.gov/sun-corona">corona</a>, or its outer atmosphere, behind the Moon’s silhouette. </p>
<p>The Moon’s orbit around the Earth is an ellipse, so the Moon can appear to be 15% smaller when it’s at its farthest point from Earth, its apogee, compared with its size when it is at its closest point to Earth, its perigee. An <a href="https://solarsystem.nasa.gov/eclipses/about-eclipses/types/">annular eclipse</a> occurs when the Moon doesn’t cover the entire disk of the Sun, leaving a ring of sunlight around the Moon.</p>
<p>Finally, a <a href="https://solarsystem.nasa.gov/eclipses/about-eclipses/types/">partial eclipse</a> occurs when the Moon blocks only a part of the Sun’s disk, as the name implies. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/534387/original/file-20230627-7269-yw2py4.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Three eclipse images: in the first the sun is entirely blocked, with shadowy light visible from behind the Moon. Second shows the sun mostly blocked, with a thin ring visible behind the Moon. Third shows the sun partially blocked" src="https://images.theconversation.com/files/534387/original/file-20230627-7269-yw2py4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/534387/original/file-20230627-7269-yw2py4.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=200&fit=crop&dpr=1 600w, https://images.theconversation.com/files/534387/original/file-20230627-7269-yw2py4.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=200&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/534387/original/file-20230627-7269-yw2py4.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=200&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/534387/original/file-20230627-7269-yw2py4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=252&fit=crop&dpr=1 754w, https://images.theconversation.com/files/534387/original/file-20230627-7269-yw2py4.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=252&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/534387/original/file-20230627-7269-yw2py4.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=252&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">From left to right: total, annular and partial solar eclipses.</span>
<span class="attribution"><a class="source" href="https://solarsystem.nasa.gov/eclipses/about-eclipses/types/">Credits: Total eclipse, left: NASA/MSFC/Joseph Matus; annular eclipse, center: NASA/Bill Dunford; partial eclipse, right: NASA/Bill Ingalls</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>Meteor showers are a far more common astronomical event than eclipses, and they are visible from any dark-sky location on Earth. Meteor showers occur when Earth’s orbit around the Sun takes it through the dust <a href="https://spaceplace.nasa.gov/meteor-shower/en/">left behind by a comet</a>. The Earth sweeps up the dust like a car speeding through a cloud of insects on the highway. </p>
<p>Meteor showers are named for the constellations from which the meteors <a href="https://spaceplace.nasa.gov/meteor-shower/en/">seem to emanate</a>, though it’s not necessary to stare in that direction to see meteors. The most prominent meteor showers, occurring on approximately the same dates every year, are the <a href="https://solarsystem.nasa.gov/asteroids-comets-and-meteors/meteors-and-meteorites/lyrids/in-depth/">Lyrids</a>, named for the constellation Lyra, on April 21-22; the <a href="https://solarsystem.nasa.gov/asteroids-comets-and-meteors/meteors-and-meteorites/perseids/in-depth/">Perseids</a>, named for the constellation Perseus and peaking on the night of Aug. 12-13; and the <a href="https://solarsystem.nasa.gov/asteroids-comets-and-meteors/meteors-and-meteorites/geminids/in-depth/">Geminids</a>, named for the constellation Gemini, on Dec. 14-15. The night sky will be mostly <a href="https://www.space.com/39469-best-meteor-showers.html">moonless</a> for the first two this year, but a nearly full moon will make the Lyrid shower of 2024 difficult to see.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/534918/original/file-20230629-27-bra2st.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Photo showing a dark sky with several bright streaks representing meteors." src="https://images.theconversation.com/files/534918/original/file-20230629-27-bra2st.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/534918/original/file-20230629-27-bra2st.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=507&fit=crop&dpr=1 600w, https://images.theconversation.com/files/534918/original/file-20230629-27-bra2st.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=507&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/534918/original/file-20230629-27-bra2st.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=507&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/534918/original/file-20230629-27-bra2st.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=637&fit=crop&dpr=1 754w, https://images.theconversation.com/files/534918/original/file-20230629-27-bra2st.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=637&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/534918/original/file-20230629-27-bra2st.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=637&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Meteor showers happen around the same time each year, and on cloudless nights they can be stunning to watch.</span>
<span class="attribution"><a class="source" href="https://media.gettyimages.com/id/609979986/photo/geminids-meteor-shower.jpg?s=612x612&w=0&k=20&c=ytVX2F9x81UHjwH18tAU0kS8uZGzpSJBJQz0tF1Fdp4=">Haitong Yu/Moment via Getty Images</a></span>
</figcaption>
</figure>
<h2>Tips for aspiring astro-tourists</h2>
<p>One of the most important factors to consider when planning an outing to stargaze or to watch a meteor shower is the phase of the Moon. The full moon rises at about 6 p.m. and sets at 6 a.m., making stargazing all but impossible because of its brightness. For ideal stargazing conditions, the Moon should be below the horizon, and the best viewing conditions are during a new moon. You can use a <a href="https://www.timeanddate.com/moon/">moonrise/moonset calculator</a> to determine the phase of the Moon and its rise and set times for any location on Earth. </p>
<p>Another important factor is weather. Amateur astronomers always joke that the sky is cloudy during the most interesting astronomical events. For example, most major cities in the U.S. that are in the path of the April 2024 eclipse have had cloudy skies on April 8 <a href="https://www.timeanddate.com/eclipse/solar/2024-april-8">60% of the time</a> since the year 2000. </p>
<p>Most Americans live in heavily light-polluted areas. A light pollution map such as <a href="https://www.lightpollutionmap.info">lightpollutionmap.info</a> can help identify the nearest dark-sky location, which, in my case, is hours away. These maps often use the <a href="https://skyandtelescope.org/astronomy-resources/light-pollution-and-astronomy-the-bortle-dark-sky-scale/">Bortle dark-sky scale</a>, which reports 1 for extremely dark skies to 9 for highly light-polluted city centers. </p>
<p>Though you may still see the brightest meteors from city suburbs, the darker your sky, the more meteors you’ll see. In general, expect to see <a href="https://solarsystem.nasa.gov/asteroids-comets-and-meteors/meteors-and-meteorites/perseids/in-depth/">fewer than 25 meteors per hour</a>. To see the complex structure of the Milky Way with the naked eye, look for a location with a Bortle index of 3 or below. </p>
<p>It’s important to arrive at your chosen site early, preferably during daylight hours. Stumbling around in the dark at an unfamiliar site is a recipe for disaster and may also disturb others who are already at the site. Arriving early also gives time for your eyes to adapt to the dark as night falls, as it typically takes <a href="https://theconversation.com/how-do-my-eyes-adjust-to-the-dark-and-how-long-does-it-take-124044">30 minutes</a> or even longer for your eyes to reach their full dark-adapted potential.</p>
<p>Make sure to carry a headlamp or flashlight that has a red light setting, as red light <a href="https://www.nps.gov/articles/dark-adaptation-of-the-human-eye-and-the-value-of-red-flashlights.htm">doesn’t ruin night vision</a>. Avoid using your phone, as even a glance at the screen can ruin your eyes’ dark adaptation. If you’re using a sky-viewing app, switch the app to night mode. </p>
<p>If you’re in the <a href="https://www.greatamericaneclipse.com">path of the April 2024 eclipse</a>, stay put. If you’re traveling, staying at the same location overnight before and after the eclipse can help avoid the hourslong <a href="https://mashable.com/article/eclipse-traffic">traffic jams</a> experienced by eclipse watchers in 2017. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/534364/original/file-20230627-23-etm2qb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A man looking up at the sky, wearing gray paper eclipse glasses." src="https://images.theconversation.com/files/534364/original/file-20230627-23-etm2qb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/534364/original/file-20230627-23-etm2qb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/534364/original/file-20230627-23-etm2qb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/534364/original/file-20230627-23-etm2qb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/534364/original/file-20230627-23-etm2qb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/534364/original/file-20230627-23-etm2qb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/534364/original/file-20230627-23-etm2qb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Eclipse glasses protect your eyes while viewing an eclipse. You should never look directly at the Sun.</span>
<span class="attribution"><a class="source" href="https://media.gettyimages.com/id/1197354027/photo/young-man-looking-up-at-solar-eclipse-wearing-paper-protective-glasses.webp?s=1024x1024&w=gi&k=20&c=h6U-p60XA4CD_9F5uk_a2Rhd9wwZGWptSxwGGYBY2Bc=">Cavan Images/Cavan via GettyImages</a></span>
</figcaption>
</figure>
<p>Also, you should never look directly at the Sun with the naked eye, <a href="https://eclipse.aas.org/sites/eclipse.aas.org/files/Chou-Solar-Eclipse-Eye-Safety-AAS-2016.pdf">even during a total eclipse</a>. You’ll need a pair of inexpensive <a href="https://www.webmd.com/eye-health/what-to-know-solar-eclipse-glasses">eclipse glasses</a> to watch and fully enjoy the eclipse, but get yours early, as many stores <a href="https://www.nola.com/archive/sorry-eclipse-enthusiasts-viewing-glasses-sold-out-across-new-orleans/article_087ba5ba-750b-5337-80e4-88611093ede8.html">ran out of glasses</a> during the 2017 eclipse. </p>
<p>No matter where you travel, don’t forget to look up at night and marvel at the beauty of the night sky, away from city lights.</p>
<p><em>This is an updated version of an article originally published on July 5, 2023.</em></p><img src="https://counter.theconversation.com/content/207969/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Vahe Peroomian received funding in the past from NASA and the National Science Foundation. Last year of funding was 2014.</span></em></p>With a solar eclipse and several meteor showers coming up, an astronomy professor shares travel tips for viewing astronomical phenomena.Vahe Peroomian, Professor of Physics and Astronomy, USC Dornsife College of Letters, Arts and SciencesLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2005402023-04-17T20:03:19Z2023-04-17T20:03:19ZWant to see a total solar eclipse? Here’s how to plan for it – and how to set your expectations in case of clouds<figure><img src="https://images.theconversation.com/files/517830/original/file-20230328-18-nopqgo.jpg?ixlib=rb-1.1.0&rect=516%2C283%2C4767%2C2892&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://unsplash.com/photos/c6smsrHupGM">Jim Strasma</a></span></figcaption></figure><p>This week, eclipse chasers will be visiting the small town of Exmouth, at the tip of North West Cape in Western Australia. Weather permitting, they are coming to see one of nature’s greatest sights – <a href="https://asa.astronomy.org.au/wp-content/uploads/2023/02/Eclipse-Fact-Sheet-updated.pdf">a total eclipse of the Sun</a> on Thursday April 20.</p>
<p>Whether staying at hotels, resorts or camping sites, many would have made travel arrangements a year or more in advance. But don’t be too disappointed if you can’t be there; other opportunities to see total eclipses are coming up in the next few years. Here’s what you need to know.</p>
<h2>A fully immersive experience</h2>
<p>A total solar eclipse occurs on those rare occasions when the Moon lines up with the Sun and passes in front of it from our vantage point here on Earth. The bright disc of the Sun is entirely hidden for a short period – seconds or minutes. During this time, called the totality, eclipse watchers will see a dark hole in the sky where the Sun had been, surrounded by a faint glow – <a href="https://spaceplace.nasa.gov/sun-corona/en/">our star’s corona</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-what-is-a-solar-eclipse-33019">Explainer: what is a solar eclipse?</a>
</strong>
</em>
</p>
<hr>
<p>This is what eclipse chasers seek to witness. The string of locations where a total eclipse will be visible to observers is called the “path of totality”. People will often travel thousands of kilometres to be in the right place at the right time. They are not only treated to the magnificent sight of the corona, but get a fully immersive experience.</p>
<p>The sky rapidly darkens, the temperature drops, birds stop twittering and animals start going to sleep. The gathered observers, whether from your own group or from distant countries, are united in the experience.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/512314/original/file-20230226-2823-j0lj30.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="The dark spot of the eclipsed Sun is surrounded by a broad ring of white light, the corona" src="https://images.theconversation.com/files/512314/original/file-20230226-2823-j0lj30.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/512314/original/file-20230226-2823-j0lj30.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/512314/original/file-20230226-2823-j0lj30.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/512314/original/file-20230226-2823-j0lj30.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/512314/original/file-20230226-2823-j0lj30.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/512314/original/file-20230226-2823-j0lj30.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/512314/original/file-20230226-2823-j0lj30.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">Totality in 2002, as seen from the Woomera Rocket Range. Contrast has been slightly stretched to emphasise the shadow and the corona.</span>
<span class="attribution"><span class="source">Nick Lomb</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-hybrid-solar-eclipse-is-about-to-be-visible-in-australia-heres-when-and-where-you-can-see-it-203338">A 'hybrid' solar eclipse is about to be visible in Australia. Here's when and where you can see it</a>
</strong>
</em>
</p>
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<h2>An addictive hobby</h2>
<p>There are two warnings associated with total solar eclipses. One is that chasing them is addictive. Often people who have seen their first eclipse immediately want to start planning to see their second.</p>
<p>I can vouch for this personally – after watching my first total eclipse on December 4 2002 from the Woomera Rocket Range, I became most keen to observe another. Seeing the corona surrounding the dark Sun come into view was an awe-inspiring experience, heightened by the fascinating location and the elation of fellow observers. My next eclipse was on August 1 2008 at an even more interesting location – a beach on the shore of the <a href="https://en.wikipedia.org/wiki/Novosibirsk_Reservoir">Novosibirsk Reservoir</a> in Siberia; and most recently, I watched the Far North Queensland eclipse on November 14 2012.</p>
<p>The other warning is this: the only time it’s safe to look directly at the Sun is during the brief period of totality. All other times, during the partial phases before and after, it is necessary to take precautions.</p>
<p>For this, special <a href="https://www.ozscopes.com.au/ozscopes-solar-eclipse-glass.html">eclipse glasses</a> are available from planetariums, public observatories, amateur astronomy groups and astronomy stores. Just make sure the glasses have the CE European standard mark.</p>
<p>Taking photographs is safe, though only during totality unless you have the appropriate filters. A tripod is essential, as the corona is faint and you will need long exposures. Seasoned eclipse observers arrive at eclipse sites loaded with professional-grade cameras and telephoto lenses. But if it’s your first time, it’s probably better to just watch and absorb the event, rather than try photographing it.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/517836/original/file-20230328-2416-1hfnt5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Several people wearing black paper glasses looking at the sky in awe" src="https://images.theconversation.com/files/517836/original/file-20230328-2416-1hfnt5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/517836/original/file-20230328-2416-1hfnt5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/517836/original/file-20230328-2416-1hfnt5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/517836/original/file-20230328-2416-1hfnt5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/517836/original/file-20230328-2416-1hfnt5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/517836/original/file-20230328-2416-1hfnt5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/517836/original/file-20230328-2416-1hfnt5.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">Tourists and locals gaze in awe at the partial solar eclipse in Midtown Manhattan’s Bryant Park on August 21 2017.</span>
<span class="attribution"><span class="source">Mihai O Coman/Shutterstock</span></span>
</figcaption>
</figure>
<h2>Plan ahead and stay mobile</h2>
<p>After this week’s eclipse in Australia, the next total solar eclipse will be visible on April 8 2024 from the United States and Mexico. After passing through Mexico, <a href="https://www.mreclipse.com/pubs/EB2024.html">the path of totality</a> sweeps across the United States from Texas to Maine, before moving to parts of Canada.</p>
<p>There are many potential viewing spots along the path. However, before picking a site, it’s important to study the “<a href="https://eclipsophile.com/2024tse/">climate report</a>” for the eclipse. This grants the best chance of avoiding the eclipse watcher’s greatest enemy – clouds.</p>
<p>However, even with the best advance planning, last-minute clouds are possible. Seasoned observers try to stay mobile, so that if the weather forecast is bad for their location, they can move to another location to avoid the clouds.</p>
<p>The US total solar eclipse will be followed on August 12 2026 with one where the <a href="http://xjubier.free.fr/en/site_pages/solar_eclipses/TSE_2026_GoogleMapFull.html">path of totality</a> passes over Spain and Iceland. Then there will be one on <a href="http://xjubier.free.fr/en/site_pages/solar_eclipses/TSE_2027_GoogleMapFull.html">August 2 2027</a>, visible from Egypt and Saudi Arabia.</p>
<p>An upcoming eclipse of greatest interest to Australians is the total solar eclipse on <a href="http://xjubier.free.fr/en/site_pages/solar_eclipses/TSE_2028_GoogleMapFull.html">July 22 2028</a>, for which the path of totality passes from WA through the Northern Territory to New South Wales towns such as Bourke, Dubbo and Mudgee before reaching Sydney. It is rare for a major city to be in the path of totality, and the <a href="https://abs.gov.au/census/find-census-data/quickstats/2021/1GSYD">five million</a> people of Sydney will get a once-in-a-lifetime opportunity to view a total solar eclipse from their homes or backyards.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/512318/original/file-20230227-4840-qmxdzg.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A small cloud covering an edge of the corona surrounding the dark disc of the eclipsed Sun" src="https://images.theconversation.com/files/512318/original/file-20230227-4840-qmxdzg.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/512318/original/file-20230227-4840-qmxdzg.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/512318/original/file-20230227-4840-qmxdzg.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/512318/original/file-20230227-4840-qmxdzg.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/512318/original/file-20230227-4840-qmxdzg.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/512318/original/file-20230227-4840-qmxdzg.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/512318/original/file-20230227-4840-qmxdzg.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">At the start of totality for the 2012 eclipse, a small cloud was in front of the Sun, but moved quickly away.</span>
<span class="attribution"><span class="source">Nick Lomb</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Of course, like at any other eclipse, clouds are a possibility, so keep a lookout for weather reports closer to the date. Before eclipse day, look at the forecasts from the <a href="http://www.bom.gov.au/">Bureau of Meteorology</a> and <a href="https://www.cloudfreenight.com/">specialised astronomy websites</a>.</p>
<p>As mentioned, for serious eclipse observers, mobility before a total eclipse is essential. For example, at the <a href="https://astronomy.org.au/wp-content/uploads/2012/11/factsheet_23rev2x.pdf">November 14 2012</a> eclipse in Far North Queensland, a Sydney Observatory group made a successful last minute <a href="https://www.maas.museum/observations/2012/12/14/total-solar-eclipse-tour-2012/">dash inland</a> to avoid the forecast poor weather.</p>
<p>Clouds, however, are not all bad. For the same eclipse, I was at <a href="https://www.maas.museum/observations/2012/11/20/total-eclipse-of-14-november-2012-from-palm-cove/">Palm Cove Beach</a> and fortunately, the clouds parted just at the start of totality. The excitement involved made for a fantastic and unique experience.</p>
<p>If you are not at North West Cape this week and want to experience the wonders of a future total solar eclipse, you may want to start planning now.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/since-the-late-19th-century-adventurous-female-eclipse-chasers-have-contributed-to-science-in-australia-200552">Since the late 19th century, adventurous female 'eclipse chasers' have contributed to science in Australia</a>
</strong>
</em>
</p>
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<img src="https://counter.theconversation.com/content/200540/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nick Lomb 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>Witnessing a total solar eclipse can be an unforgettable experience – and apparently, quite addictive.Nick Lomb, Honorary Professor, Centre for Astrophysics, University of Southern QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2020342023-04-16T20:04:20Z2023-04-16T20:04:20ZHumans have been predicting eclipses for thousands of years, but it’s harder than you might think<figure><img src="https://images.theconversation.com/files/518381/original/file-20230330-362-8tm80s.jpg?ixlib=rb-1.1.0&rect=179%2C67%2C2631%2C1800&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Antikythera mechanism in National Archaeological Museum, Athens, Greece.</span> <span class="attribution"><span class="source">Viacheslav Lopatin/Shutterstock</span></span></figcaption></figure><p>The coastal town of Exmouth in Western Australia is due to experience one of the most spectacular astronomical phenomena on April 20 2023 – <a href="https://www.timeanddate.com/eclipse/solar/2023-april-20">a total solar eclipse</a>.</p>
<p>Eclipses have entranced us for millennia. But it turns out calculating exactly when and where we can watch an eclipse in its full glory can be surprisingly hard.</p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/since-the-late-19th-century-adventurous-female-eclipse-chasers-have-contributed-to-science-in-australia-200552">Since the late 19th century, adventurous female 'eclipse chasers' have contributed to science in Australia</a>
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<h2>Watching the Sun and the Moon</h2>
<p>Being so dominant in the sky, the Sun and the Moon were the most captivating celestial bodies for ancient cultures to observe. Naturally, they also tried to anticipate and predict their motions.</p>
<p>While the Sun’s movement is quite simple, the Moon moves across the sky with much more complexity. For one thing, it has phases; it also grows and shrinks in apparent size as it travels on an elliptical orbit around Earth.</p>
<p>On top of this, the Moon appears to rock and wobble quite haphazardly on its journey across the sky, making it extremely challenging to accurately describe its orbit. In fact, explaining the Moon’s motion <a href="https://www.newtonproject.ox.ac.uk/view/texts/normalized/OTHE00079">was the only problem that made Isaac Newton’s head hurt</a>.</p>
<p>Since eclipses are so startling to witness, many ancient peoples both noted their occurrence in writing and art, and discovered the repeating characteristics of such events.</p>
<p>During a lunar eclipse, where Earth blocks sunlight that would otherwise illuminate a full moon, the dimmed Moon takes on a bloody hue. Many cultures attached foreboding to such events (like the <a href="https://en.wikipedia.org/wiki/May_1453_lunar_eclipse">partial lunar eclipse seen during the Fall of Constantinople in 1453</a>) and quite reasonably wondered when the next such event might occur.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/520384/original/file-20230412-28-3c2zbl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A moon shaded orange with a brighter white edge on top on a black background" src="https://images.theconversation.com/files/520384/original/file-20230412-28-3c2zbl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/520384/original/file-20230412-28-3c2zbl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/520384/original/file-20230412-28-3c2zbl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/520384/original/file-20230412-28-3c2zbl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/520384/original/file-20230412-28-3c2zbl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/520384/original/file-20230412-28-3c2zbl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/520384/original/file-20230412-28-3c2zbl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">A lunar eclipse visible in Miami, Florida in 2010.</span>
<span class="attribution"><span class="source">FloridaStock/Shutterstock</span></span>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/like-blood-then-turned-into-darkness-how-medieval-manuscripts-link-lunar-eclipses-volcanoes-and-climate-change-203185">‘Like blood, then turned into darkness’: how medieval manuscripts link lunar eclipses, volcanoes and climate change</a>
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<h2>The not-so-mythical Saros cycle</h2>
<p>Various cultures around the world have independently discovered eclipses seem to occur on an 18-year cycle. It was mentioned in written records by the Babylonians and Assyrians (of ancient Mesopotamia and modern Iraq), and oral tradition suggests the cycle was used for ceremonial purposes by <a href="https://www.thefirstastronomers.com">Torres Strait Islanders</a> in what is now Australia. </p>
<p>This 18-year cycle, which can persist as a sequence for over a thousand years, is now known as a <a href="https://eclipse.gsfc.nasa.gov/SEsaros/SEsaros.html">Saros cycle</a>. The word “Saros” was <a href="https://www.cs.uky.edu/%7Eraphael/sol/sol-entries/sigma/148">referenced in the 10th-century Byzantine Suda encyclopedia</a>, and possibly has a Greek origin (“saro” meaning “sweep”, perhaps relating to how eclipses sweep across the sky).</p>
<p>The Saros cycle represents how long it takes for the Sun-Earth-Moon system to return to almost exactly the same triangular configuration. So, if you see a lunar eclipse, you can expect another one 18 years later, visible from most places on Earth.</p>
<p>If you were an ancient culture that happened to observe a total solar eclipse, you would have been very lucky indeed (<a href="https://earthobservatory.nasa.gov/images/145278/total-solar-eclipse-darkens-the-south-pacific">they occur roughly every 375 years at a given region on Earth</a>). But would you have seen a similar event 18 years later? Alas, no. While there probably was another total solar eclipse 18 years later, it would have been over a completely different part of the planet. </p>
<p>After 54 years – three Saros cycles – the eclipse region should have returned to roughly the same position on Earth. But only <em>very</em> roughly, as it could be thousands of kilometres away from the previous observation spot. </p>
<p>Worldwide, there is a total solar eclipse visible somewhere roughly every 18 months during one of two possible “<a href="https://en.wikipedia.org/wiki/Eclipse_season">eclipse seasons</a>” per year. This is much more frequent than an 18-year Saros cycle, and is possible because multiple repeating Saros sequences overlap at once (roughly a dozen), each offset by at least six months. For example, the <a href="https://www.timeanddate.com/eclipse/in/australia/sydney?iso=20280722">2028 total solar eclipse that will be visible in Sydney</a> is part of an entirely different Saros sequence than this year’s eclipse.</p>
<p>After about a thousand years, when one long-term Saros sequence ends, another will begin with slightly different timing.</p>
<h2>From antiquity to modern day</h2>
<p>So could our ancient ancestors actually predict eclipses? Yes, if we are talking about lunar eclipses, and perhaps even partial solar eclipses.</p>
<p>A famous predictive example is the <a href="https://historydaily.org/the-power-of-an-eclipse-the-story-of-the-eclipse-of-thales">Eclipse of Thales</a> in 585 BCE, although the fact that a total solar eclipse happened over Greece was almost certainly more luck than science. That is, they wouldn’t have predicted that 18 years later (567 BCE) a total solar eclipse was <a href="https://eclipse.gsfc.nasa.gov/SEsaros/SEsaros057.html">visible in what is now the United States</a>. </p>
<p>It is likely the famed <a href="https://theconversation.com/antikythera-to-the-ska-lessons-from-the-ancients-7584">Greek Antikythera Mechanism</a>, an astoundingly complicated 2,000-year-old mechanical device that was used to predict the night sky, could <a href="https://www.atlasobscura.com/articles/how-to-predict-eclipse-computer-math-antikythera">calculate the 18-year Saros accurately</a>. But significantly, it could not predict total solar eclipses at a precise place on Earth – just their timing.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/519758/original/file-20230406-22-6qjaxn.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A jagged piece of material with embossed writing across it" src="https://images.theconversation.com/files/519758/original/file-20230406-22-6qjaxn.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/519758/original/file-20230406-22-6qjaxn.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=488&fit=crop&dpr=1 600w, https://images.theconversation.com/files/519758/original/file-20230406-22-6qjaxn.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=488&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/519758/original/file-20230406-22-6qjaxn.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=488&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/519758/original/file-20230406-22-6qjaxn.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=613&fit=crop&dpr=1 754w, https://images.theconversation.com/files/519758/original/file-20230406-22-6qjaxn.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=613&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/519758/original/file-20230406-22-6qjaxn.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=613&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 Saros period (marked with a red rectangle) is visible on a fragment of the ‘user manual’ of the Antikythera mechanism.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/File:Manual2021-X_MOUSSAS_SAROS.jpg">Xmoussas/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>In summary, it is clear ancient people could predict timings for lunar eclipses and partial solar eclipses, but there is no convincing evidence of people predicting the times and locations of total solar eclipses. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/516626/original/file-20230321-502-z8b65n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/516626/original/file-20230321-502-z8b65n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/516626/original/file-20230321-502-z8b65n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=735&fit=crop&dpr=1 600w, https://images.theconversation.com/files/516626/original/file-20230321-502-z8b65n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=735&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/516626/original/file-20230321-502-z8b65n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=735&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/516626/original/file-20230321-502-z8b65n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=923&fit=crop&dpr=1 754w, https://images.theconversation.com/files/516626/original/file-20230321-502-z8b65n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=923&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/516626/original/file-20230321-502-z8b65n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=923&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">The path of the eclipse as described by Halley in 1715.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:HalleyEclipse1715Path.jpg">University of Cambridge, Institute of Astronomy Library</a></span>
</figcaption>
</figure>
<p>Entering the modern era of science, the first true prediction of a total solar eclipse (both in time and location) occurred in 1715. Edmond Halley (of comet fame) <a href="https://www.atlasobscura.com/articles/eclipse-maps-halley-18th-century-astronomy">correctly predicted</a>, to within four minutes and 20 miles, a total solar eclipse that rather conveniently passed over his own house in London. He did this by making full use of Isaac Newton’s new theories of gravity and orbital mechanics: the <a href="https://plato.stanford.edu/entries/newton-principia/">Principia</a>.</p>
<p>Today, we don’t rely on calculating the orbits of the whole Solar System to predict eclipses. For example, NASA uses a highly advanced form of an ancient technique – pattern recognition. <a href="https://eclipse.gsfc.nasa.gov/SEpath/ve82-predictions.html">Using some 38,000 repeating mathematical terms</a>, NASA can predict both solar and lunar eclipses <a href="https://eclipse.gsfc.nasa.gov/SEpubs/5MCSE.html">for 1,000 years into the future</a>. Beyond that, the Moon’s wobble and Earth’s changing rotation make eclipse prediction less accurate. </p>
<p>So for those of you lucky enough to witness a total solar eclipse this month, take a moment to think about what this shared experience has meant to humans around the world for thousands of years.</p>
<p>Trying to predict and explain this phenomenon has directly driven advancements in mathematics and orbital mechanics, and with its beauty we have been forced to embrace the limits of our scientific knowledge.</p><img src="https://counter.theconversation.com/content/202034/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Aaron Robotham receives funding from the Australian Research Council (ARC). </span></em></p><p class="fine-print"><em><span>Sabine Bellstedt 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>Calculating when and where exactly we can watch an eclipse in its full glory can be surprisingly hard.Aaron Robotham, Research Associate Professor & UWA Research Fellow, The University of Western AustraliaSabine Bellstedt, Research Fellow in Astronomy, The University of Western AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2033382023-04-13T00:20:04Z2023-04-13T00:20:04ZA ‘hybrid’ solar eclipse is about to be visible in Australia. Here’s when and where you can see it<figure><img src="https://images.theconversation.com/files/520462/original/file-20230412-28-9l9bbx.jpeg?ixlib=rb-1.1.0&rect=287%2C310%2C1273%2C776&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://images.nasa.gov/details/AFRC2017-0233-009">NASA/Carla Thomas</a></span></figcaption></figure><p>On Thursday 20 April, the Ningaloo region of Western Australia will experience a total solar eclipse. Eclipse chasers from around the world are converging on the town of Exmouth in hopes of experiencing the profound awe of standing in the Moon’s shadow as it quickly races by. </p>
<p>Only <a href="http://xjubier.free.fr/en/site_pages/solar_eclipses/HSE_2023_GoogleMapFull.html">a narrow path across Earth</a>, which includes Exmouth and Barrow Island WA, eastern parts of East Timor and also parts of Papua in Indonesia, will experience totality – when the Moon <em>fully</em> blocks the light of the Sun. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/520240/original/file-20230411-18-3lvapu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map of Australia and Indonesia showing the path of totality from Exmouth WA to Papua, Indonesia." src="https://images.theconversation.com/files/520240/original/file-20230411-18-3lvapu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/520240/original/file-20230411-18-3lvapu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=529&fit=crop&dpr=1 600w, https://images.theconversation.com/files/520240/original/file-20230411-18-3lvapu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=529&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/520240/original/file-20230411-18-3lvapu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=529&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/520240/original/file-20230411-18-3lvapu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=665&fit=crop&dpr=1 754w, https://images.theconversation.com/files/520240/original/file-20230411-18-3lvapu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=665&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/520240/original/file-20230411-18-3lvapu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=665&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Only locations along a narrow path will have the chance to see the total solar eclipse.</span>
<span class="attribution"><span class="source">Xavier M. Jubier</span></span>
</figcaption>
</figure>
<h2>Can we see the eclipse in other parts of Australia?</h2>
<p>Across the rest of Australia, we will get a partial solar eclipse. Exactly how much of the Sun is covered by the Moon, as well as the timing of the eclipse, depends on your location. The farther away from the path of totality, the shallower the eclipse will be.</p>
<p>Comparing Australian capital cities, Darwin will experience the deepest partial eclipse – with 85% of the Sun’s diameter hidden by the Moon. For Hobart, located at the other end of the country from Ningaloo, just 13% of the Sun’s diameter will disappear behind the Moon. </p>
<p>During a partial eclipse, there is nothing to notice or clue you in that an eclipse might even be happening. Even when 90% or more of the Sun’s diameter is obscured by the Moon (known as the eclipse magnitude) you might only notice a very slight dimming of daylight. More so, the colours and light around you may look a little strange.</p>
<p>The local circumstances for the eclipse across Australian capital cities are provided in the tables below. To find out what’s happening in your location, you can use <a href="https://www.timeanddate.com/eclipse/map/2023-april-20">timeanddate.com</a>
or an <a href="http://xjubier.free.fr/en/site_pages/solar_eclipses/HSE_2023_GoogleMapFull.html">online Google map</a> created by French amateur astronomer Xavier Jubier (note that all times will need to be converted from UTC).</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/520270/original/file-20230411-22-genm97.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/520270/original/file-20230411-22-genm97.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/520270/original/file-20230411-22-genm97.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=221&fit=crop&dpr=1 600w, https://images.theconversation.com/files/520270/original/file-20230411-22-genm97.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=221&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/520270/original/file-20230411-22-genm97.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=221&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/520270/original/file-20230411-22-genm97.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=277&fit=crop&dpr=1 754w, https://images.theconversation.com/files/520270/original/file-20230411-22-genm97.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=277&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/520270/original/file-20230411-22-genm97.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=277&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
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<span class="attribution"><span class="source">Tanya Hill</span></span>
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</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/520273/original/file-20230411-22-ll9lol.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/520273/original/file-20230411-22-ll9lol.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/520273/original/file-20230411-22-ll9lol.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=324&fit=crop&dpr=1 600w, https://images.theconversation.com/files/520273/original/file-20230411-22-ll9lol.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=324&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/520273/original/file-20230411-22-ll9lol.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=324&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/520273/original/file-20230411-22-ll9lol.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=407&fit=crop&dpr=1 754w, https://images.theconversation.com/files/520273/original/file-20230411-22-ll9lol.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=407&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/520273/original/file-20230411-22-ll9lol.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=407&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"></span>
<span class="attribution"><span class="source">Tanya Hill</span></span>
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<h2>What is a ‘hybrid’ eclipse?</h2>
<p>Technically, this solar eclipse is a special type, known as a hybrid eclipse. It begins over the Indian Ocean as an <a href="https://moon.nasa.gov/resources/74/annular-eclipse/">annular eclipse</a>, where the Moon is slightly too small to completely block the Sun and a ring of sunlight shines out from around the dark Moon. This happens when the Moon’s antumbral shadow hits Earth (see diagram).</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/520469/original/file-20230412-14-s4b4pq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram showing the location of the different types of shadow the Moon casts" src="https://images.theconversation.com/files/520469/original/file-20230412-14-s4b4pq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/520469/original/file-20230412-14-s4b4pq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=253&fit=crop&dpr=1 600w, https://images.theconversation.com/files/520469/original/file-20230412-14-s4b4pq.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=253&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/520469/original/file-20230412-14-s4b4pq.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=253&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/520469/original/file-20230412-14-s4b4pq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=317&fit=crop&dpr=1 754w, https://images.theconversation.com/files/520469/original/file-20230412-14-s4b4pq.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=317&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/520469/original/file-20230412-14-s4b4pq.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=317&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">During an annular eclipse, the Moon’s umbral shadow is not long enough to reach Earth and Earth is immersed in the antumbral shadow instead (diagram not to scale).</span>
<span class="attribution"><span class="source">The Conversation</span></span>
</figcaption>
</figure>
<p>By the time the Moon’s shadow reaches land, it will become a total eclipse – the Moon now appears large enough to completely block the Sun, and it is the Moon’s umbral shadow that falls on Earth.</p>
<p>It’s incredible that such an eclipse occurs, because it means Earth is situated in the sweet spot between the umbral and antumbral shadows. Parts of Earth are in the umbral shadow, while the curvature of the planet is enough to make other places sit slightly farther away, so that the antumbral shadow falls there.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/yL1rnAGm8g0?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The Japanese weather satellite Himawari-8, captured the Moon’s shadow racing across Earth during a total solar eclipse on 9 March 2016.</span></figcaption>
</figure>
<h2>Don’t forget about eye safety!</h2>
<p>Most importantly, a solar eclipse requires special precautions to observe it safely. <strong>Never look directly at the Sun because it can cause serious and permanent eye damage.</strong> </p>
<p>You can observe a solar eclipse safely by <a href="https://eclipse.asa.astronomy.org.au/how-to-view/">protecting your eyes</a> with certified eclipse glasses or view the Sun indirectly by creating a <a href="https://www.jpl.nasa.gov/edu/learn/project/how-to-make-a-pinhole-camera/">pinhole camera</a> to project a tiny image of the Sun onto a wall, the ground or a piece of paper.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/520239/original/file-20230411-22-74me02.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Light from the Sun shines through the holes of a colander and onto a wall, creating many little images of the eclipsed Sun projected onto the wall" src="https://images.theconversation.com/files/520239/original/file-20230411-22-74me02.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/520239/original/file-20230411-22-74me02.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/520239/original/file-20230411-22-74me02.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/520239/original/file-20230411-22-74me02.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/520239/original/file-20230411-22-74me02.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/520239/original/file-20230411-22-74me02.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/520239/original/file-20230411-22-74me02.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A colander is a ready to use pinhole camera, creating many tiny images of the eclipsed Sun.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/yellowbookltd/16684322010">John Lord/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Just remember this is a projection technique – <strong>do not</strong> look at the Sun through any pinholes.</p>
<h2>Observing the totality</h2>
<p>For those fortunate to be in Exmouth, the eclipse will begin at 10:04am, and totality will occur at 11:30am, producing an eerie twilight. For just 58 seconds, eclipse observers will be plunged into the Moon’s shadow for an awe-inspiring experience. </p>
<p>What’s most amazing is totality reveals a part of the Sun we don’t normally see. The Sun’s magnificent corona – its outer atmosphere – extends millions of kilometres into space and can be seen dancing and shimmering.</p>
<p>It’s also possible to see planets and bright stars during totality, if you can tear your gaze away from the shimmering corona. There are currently four planets in our daytime sky and all will be revealed – Saturn and Jupiter sitting above the Sun, with faint Mercury and bright Venus below it. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/520279/original/file-20230411-20-gald1z.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="similulation of the eclipsed sky, looking north, the planets are aligned with Saturn at highest followed by Jupiter, the eclipse, Mercury and Venus" src="https://images.theconversation.com/files/520279/original/file-20230411-20-gald1z.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/520279/original/file-20230411-20-gald1z.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=347&fit=crop&dpr=1 600w, https://images.theconversation.com/files/520279/original/file-20230411-20-gald1z.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=347&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/520279/original/file-20230411-20-gald1z.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=347&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/520279/original/file-20230411-20-gald1z.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=436&fit=crop&dpr=1 754w, https://images.theconversation.com/files/520279/original/file-20230411-20-gald1z.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=436&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/520279/original/file-20230411-20-gald1z.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=436&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">During totality there’s a chance to see four planets, weather permitting.</span>
<span class="attribution"><span class="source">Museums Victoria/Stellarium</span></span>
</figcaption>
</figure>
<p>That brief moment of totality, when the Sun is completely covered by the Moon, is the only time to safely watch the eclipse directly. All too quickly, the Moon will move on and it will be time to shield your eyes again.</p>
<h2>Australia, get ready for more</h2>
<p>Remarkably, this eclipse is the first of five total solar eclipses to occur over the next 15 years in Australia.</p>
<p>What’s more, many of the upcoming eclipses will see totality pass over highly populated areas:</p>
<ul>
<li><p><a href="https://www.timeanddate.com/eclipse/solar/2028-july-22">July 22 2028</a> – totality will cross from the Kimberley, WA, through the Northern Territory, southwest Queensland, New South Wales, and pass directly over Sydney.</p></li>
<li><p><a href="https://www.timeanddate.com/eclipse/solar/2030-november-25">Nov 25 2030</a> – totality will occur across South Australia, northwest NSW and southern QLD.</p></li>
<li><p><a href="https://www.timeanddate.com/eclipse/solar/2037-july-13">Jul 13 2037</a> – totality will cross southern WA, southern NT, western QLD, passing directly over Brisbane and the Gold Coast.</p></li>
<li><p><a href="https://www.timeanddate.com/eclipse/solar/2038-december-26">Dec 26 2038</a> – totality occurs over central WA, SA, and along the NSW/Victoria border.</p></li>
</ul>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/520241/original/file-20230411-24-vd5tb1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/520241/original/file-20230411-24-vd5tb1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/520241/original/file-20230411-24-vd5tb1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=365&fit=crop&dpr=1 600w, https://images.theconversation.com/files/520241/original/file-20230411-24-vd5tb1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=365&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/520241/original/file-20230411-24-vd5tb1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=365&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/520241/original/file-20230411-24-vd5tb1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=458&fit=crop&dpr=1 754w, https://images.theconversation.com/files/520241/original/file-20230411-24-vd5tb1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=458&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/520241/original/file-20230411-24-vd5tb1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=458&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Five total solar eclipses over Australia will occur during the next 15 years.</span>
<span class="attribution"><span class="source">Base map: Google Earth; Eclipse date: Xavier Jubier kmz files</span></span>
</figcaption>
</figure>
<p>For some Australians there will be no need to travel the world to experience totality, when you have the chance to see it from your own backyard.</p><img src="https://counter.theconversation.com/content/203338/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tanya Hill 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>Only a tiny sliver of the Australian continent will witness the totality this time around. But there are five more total eclipses coming over the next 15 years.Tanya Hill, Senior Curator (Astronomy), Museums Victoria and Honorary Fellow at University of Melbourne, Museums Victoria Research InstituteLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2033822023-04-07T15:56:02Z2023-04-07T15:56:02ZOn April 8, 2024, parts of Ontario, Québec, the Maritimes and Newfoundland will see a total eclipse of the sun. Here’s how to get ready for it.<figure><img src="https://images.theconversation.com/files/519687/original/file-20230405-22-8wx57z.jpg?ixlib=rb-1.1.0&rect=25%2C11%2C1862%2C1212&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Watching a solar eclipse is always fascinating. During the phase when the moon completely obstructs the sun, daylight gives way to a deep twilight sky.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>You might not know exactly what you will be doing a year from now, on April 8, 2024. It’s pretty hard to predict a year in advance. However, on that date, <a href="https://solarsystem.nasa.gov/eclipses/2024/apr-8-total/where-when/">a total solar eclipse will occur in parts of Mexico, the United States and Canada — including parts of southern Ontario and Québec, New Brunswick, Nova Scotia, Prince Edward Island and Newfoundland</a> — a rare phenomenon. </p>
<p>The total solar eclipse will be visible in locations including: Niagara Falls and Hamilton, Ont.; Montréal; Fredericton, N.B.; western P.E.I.; the northern tip of Cape Breton, N.S.; and Gander, Nfld.</p>
<p>Cities like Toronto and Ottawa will be just beyond the path of the total solar eclipse. </p>
<p>While partial solar eclipses happen quite frequently, the total disappearance of the sun behind the moon only occurs <a href="https://espacepourlavie.ca/en/total-or-annular-solar-eclipse">when the moon is closer to our planet or the sun is at its furthest point from it</a>. It is a question of the size of the moon compared to the sun. When the two are perfectly aligned, it creates a shadow cone that allows people on Earth who are within this narrow band to enjoy the unique spectacle of a total eclipse. </p>
<p>On average, this alignment only occurs <a href="https://espacepourlavie.ca/en/frequency-solar-eclipses">once every 375 years</a>, but it can vary. For example, the last total eclipse visible in Montréal occurred on Aug. 31, 1932. Other regions in Canada have not been as lucky. In St. John’s, Nfld., the last total eclipse was on Feb. 3, 1440, and locals will have to wait a total of 765 years for the next one, which will happen on July 17, 2205! The record belongs to Regina, Sask., which had a total eclipse in 54 BC, but will not see another one until Oct. 17, 2153 — or a total of 2207 years! </p>
<p>So try not to miss the total eclipse in places like Montréal in 2024. If you do, you’ll have to go to a location like <a href="https://espacepourlavie.ca/en/frequency-solar-eclipses">Calgary for the next one, in 20 years</a>. </p>
<p>Yet the phenomenon does pose significant risks to eye health. As an optometrist, I am very concerned about eye health issues. I certainly wouldn’t want anyone to go blind after watching a solar eclipse without properly protecting their eyes.</p>
<h2>Watch it, but protect yourself</h2>
<p>Watching a total solar eclipse is always fascinating. During the phase when the moon completely obstructs the sun, daylight is transformed into a deep twilight sky. The sun’s outer atmosphere (known as the sun’s corona) gradually appears, <a href="https://solarsystem.nasa.gov/eclipses/2024/apr-8-total/overview/">shining like a halo around the moon</a>. The bright stars and planets become more visible in the sky.</p>
<p>In daylight, the sun usually emits visible light that is so intense we cannot look directly at it for very long. If our eye ever looks directly at the sun, we have the reflex of turning away from it immediately, after <a href="https://ehs.lbl.gov/resource/documents/radiation-protection/non-ionizing-radiation/light-and-infrared-radiation/#:%7E:text=Prolonged%20exposure%20to%20IR%20radiation,eye%2C%20swelling%2C%20or%20hemorrhaging">an average of only 0.25 seconds</a>. This reflex provides natural protection for eyes against the harmful rays of the sun, some of which — notably ultraviolet and infrared radiation — are not visible. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/519350/original/file-20230404-18-rpgn0r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="total solar eclipse" src="https://images.theconversation.com/files/519350/original/file-20230404-18-rpgn0r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/519350/original/file-20230404-18-rpgn0r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/519350/original/file-20230404-18-rpgn0r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/519350/original/file-20230404-18-rpgn0r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/519350/original/file-20230404-18-rpgn0r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/519350/original/file-20230404-18-rpgn0r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/519350/original/file-20230404-18-rpgn0r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">During a total solar eclipse, the sun’s outer atmosphere (called the solar corona) gradually appears, shining like a halo around the moon that faces it.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<h2>Ultraviolet radiation (UV)</h2>
<p>UVs accounts for <a href="https://ehs.lbl.gov/resource/documents/radiation-protection/non-ionizing-radiation/light-and-infrared-radiation/#:%7E:text=Prolonged%20exposure%20to%20IR%20radiation,eye%2C%20swelling%2C%20or%20hemorrhaging.">seven per cent of solar radiation</a>. They are partly absorbed by the cornea (the clear part at the front of the eye) and the crystalline lens (the natural lens inside the eye), without causing any damage, unless the exposure is too great. </p>
<p>In such cases, depending on the amount of UV radiation it absorbs, the cornea may develop inflammation, known as keratitis. The lens, in turn, loses its transparency — this is called a cataract. Other impacts can be expected, such as the development of <a href="https://www.nei.nih.gov/about/news-and-events/news/protecting-your-eyes-suns-uv-light#:%7E:text=Prolonged%20exposure%20to%20UV%20rays,are%20linked%20to%20UV%20exposure">small cysts (pinguecula) on the conjunctiva (white of the eye) or a membrane invading the cornea (pterygium)</a>.</p>
<p>Eyelids can also develop skin cancers. The upper eyelid, which is usually not exposed on the outside when our eyes are open, is particularly at risk when we lie on the beach with our eyes closed without protection. Finally, UV light predisposes us to <a href="https://theconversation.com/macular-degeneration-is-a-leading-cause-of-blindness-heres-how-to-prevent-it-160683">macular degeneration</a>, which is a damage to our best retinal cells and can result in varying degrees of vision loss.</p>
<p>These <a href="https://www.aao.org/eye-health/tips-prevention/sun">diseases</a> all develop as a result of direct radiation, but can also come about when the sun’s rays are strongly reflected by surfaces such as snow (snow ophthalmia), sand or water. It is therefore recommended to wear protective eyewear that cuts out all UV rays (UV400 protection) when you plan to spend more than a few minutes in the sun. For both <a href="https://theconversation.com/summer-is-here-why-you-need-to-protect-your-childrens-eyes-116498">children</a> and adults, the frame should wrap around the eyes, so that no rays pass through the side or top.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/519354/original/file-20230404-2216-nwlh6e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="child wears sunglasses at the beach" src="https://images.theconversation.com/files/519354/original/file-20230404-2216-nwlh6e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/519354/original/file-20230404-2216-nwlh6e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=390&fit=crop&dpr=1 600w, https://images.theconversation.com/files/519354/original/file-20230404-2216-nwlh6e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=390&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/519354/original/file-20230404-2216-nwlh6e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=390&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/519354/original/file-20230404-2216-nwlh6e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=490&fit=crop&dpr=1 754w, https://images.theconversation.com/files/519354/original/file-20230404-2216-nwlh6e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=490&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/519354/original/file-20230404-2216-nwlh6e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=490&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">For both children and adults, the frame of sunglasses should wrap around the eyes, so that no rays pass through from the side or top.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<h2>Infrared radiation (IR)</h2>
<p>IRs make up the majority of the radiation emitted by the sun — <a href="https://ehs.lbl.gov/resource/documents/radiation-protection/non-ionizing-radiation/light-and-infrared-radiation/#:%7E:text=Prolonged%20exposure%20to%20IR%20radiation,eye%2C%20swelling%2C%20or%20hemorrhaging">54 per cent</a>. We feel the effects because it is thermal radiation, which is accompanied by heat. </p>
<p>While the cornea (burning) and lens (cataract) can also be affected by IR, it is more the retina that can suffer from inappropriate exposure to IR. Again, it is a question of intensity and duration. As with UV radiation, the more intense the radiation, the more permanent damage will occur in a short period of time.</p>
<p>IR damage to the retina destroys the cells that allow us to see and ultimately creates a scotoma, a permanent black spot in our field of vision. This is a cause of blindness. </p>
<h2>Eclipse and radiation</h2>
<p>When the Sun is only partially hidden (partial eclipse), the UV and IR radiation is as important as in full sunlight. However, because of the reduced luminosity, we no longer have the natural reflex of turning our eyes away. So it may seem more comfortable to observe the sun for several seconds or even minutes. Without protection, this type of exposure can lead to the pathologies described above and contribute to blindness if the central retina is affected. <a href="https://www.theguardian.com/us-news/video/2017/aug/21/donald-trump-look-directly-sun-eclipse-video">U.S. President Donald Trump was reminded of this in 2017</a>, when he watched a partial eclipse without protection, putting his vision at risk. </p>
<p>During a total eclipse, however, it is possible, during the short duration of the total obstruction of the sun (one minute 37 seconds), to <a href="https://www.nasa.gov/content/eye-safety-during-a-total-solar-eclipse/#:%7E:text=During%20the%20short%20time%20when,put%20back%20on%20your%20glasses.">look at the solar corona without protection</a>. But you must be very vigilant and remember to put protection back in place as soon as the Moon starts to move and the radiation becomes present again, even though the ambient luminosity is still reduced. </p>
<p>The same precautions should be taken when viewing the eclipse directly through binoculars, a telescope, a camera or other optical means. For example, do not look at your phone screen with the naked eye when trying to take pictures of the eclipse. The rays are not blocked by these instruments and can cause significant eye damage. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/519351/original/file-20230404-988-6obvvo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Trump points at the sun" src="https://images.theconversation.com/files/519351/original/file-20230404-988-6obvvo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/519351/original/file-20230404-988-6obvvo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/519351/original/file-20230404-988-6obvvo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/519351/original/file-20230404-988-6obvvo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/519351/original/file-20230404-988-6obvvo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/519351/original/file-20230404-988-6obvvo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/519351/original/file-20230404-988-6obvvo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">President Donald Trump points at the sun without protective glasses during the partial solar eclipse on Aug. 21, 2017, at the White House in Washington, D.C.</span>
<span class="attribution"><span class="source">(AP Photo/Andrew Harnik)</span></span>
</figcaption>
</figure>
<h2>A question of protection</h2>
<p>So, what kind of eye protection are we talking about exactly? Sunscreens that can be mounted in glasses or in temporary glasses, made of cardboard, but that cover the entire surface of the eye perfectly. Once again, it is important to avoid leaving a gap between the eye and the protective screen through which harmful radiation can enter. Permitted filters <a href="https://www.aao.org/eye-health/tips-prevention/solar-eclipse-eye-safety">must meet ISO-12312-2</a>.</p>
<p>Before wearing such filters, be sure to follow the instructions provided with the equipment. It is very important for parents to ensure that children wear the filters properly and do not play with them. When the observation is over, do not remove the filters while you are still looking at the sun: look away, turn your back to the sun and remove the filters. Then don’t look at the sky anymore. </p>
<h2>If ever…</h2>
<p>Damage to the cornea and retina can occur within hours of exposure, but not always immediately. If you have ever been inadvertently or recklessly exposed, monitor your vision in the hours after the eclipse. If you notice any blurring or changes in your vision, you should consult an optometrist or ophthalmologist as soon as possible. </p>
<p>Many activities will be organized for the arrival of the total eclipse. To make the most of this unique event, watch for announcements from organizations such as <a href="https://espacepourlavie.ca/en">Space for Life</a>, institutions such as the Université de Montréal, or your local astronomy clubs. These organizations will provide information, may provide protective glasses/filters and, most importantly, will help you to better understand the phenomenon. </p>
<p>See you in a year’s time! But in the meantime, whether young and old, let’s all protect our eyes properly.</p><img src="https://counter.theconversation.com/content/203382/count.gif" alt="La Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Langis Michaud ne travaille pas, ne conseille pas, ne possède pas de parts, ne reçoit pas de fonds d'une organisation qui pourrait tirer profit de cet article, et n'a déclaré aucune autre affiliation que son organisme de recherche.</span></em></p>Some parts of North America will witness a total solar eclipse in April 2024. This may seem far away, but you should think about preparing for this rare and fascinating phenomenon.Langis Michaud, Professeur Titulaire. École d'optométrie. Expertise en santé oculaire et usage des lentilles cornéennes spécialisées, Université de MontréalLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2005522023-04-06T06:16:02Z2023-04-06T06:16:02ZSince the late 19th century, adventurous female ‘eclipse chasers’ have contributed to science in Australia<figure><img src="https://images.theconversation.com/files/519222/original/file-20230404-18-nwlh6e.jpg?ixlib=rb-1.1.0&rect=135%2C0%2C708%2C378&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Elizabeth Campbell operating the Floyd Telescope, 1922 total solar eclipse. </span> <span class="attribution"><span class="source">State Library Western Australia 4131B/3/8, enhanced detail</span>, <span class="license">Author provided</span></span></figcaption></figure><p>A total solar eclipse is a remarkable alignment of our Sun, Earth and the Moon, as the latter casts a perfect shadow across the former.</p>
<p>If you’re in the narrow path of the shadow of the Moon, at the moment of totality you are plunged into darkness. Stars and planets emerge in the sky, and the entire atmosphere changes. This immersion in a total solar eclipse is unforgettable. </p>
<p>As 21-year-old Australian Miriam Chisholm <a href="http://articles.adsabs.harvard.edu/pdf/1924MmBAA..24...94C">reported in 1922</a>,</p>
<blockquote>
<p>I looked up from the telescope just an instant before totality and thought I saw the Corona, a pale fringe around the Sun […] and then the light went out and we saw it in all its glory.</p>
</blockquote>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/516169/original/file-20230319-16-7iduc5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photograph of the black totally eclipsed sun in the centre with a white haze of corona around it. The image was encapsulated in a glass plate slide to project for teaching at Sydney Observatory." src="https://images.theconversation.com/files/516169/original/file-20230319-16-7iduc5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/516169/original/file-20230319-16-7iduc5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/516169/original/file-20230319-16-7iduc5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/516169/original/file-20230319-16-7iduc5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/516169/original/file-20230319-16-7iduc5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/516169/original/file-20230319-16-7iduc5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/516169/original/file-20230319-16-7iduc5.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">Photograph of the solar corona taken using the Floyd Camera by Elizabeth Campbell, 21 September 1922. The image was later used for teaching at Sydney Observatory. Collection Museum of Applied Arts and Sciences.</span>
</figcaption>
</figure>
<p>Historically, total solar eclipses were a unique opportunity to conduct scientific research about our Sun, the closest star. Using special instruments called spectroscopes, it was possible to decipher the chemical composition of the gases emitted by the Sun – but only during a total eclipse. </p>
<p>As I write in my recently co-authored book <a href="https://ebooks.publish.csiro.au/content/eclipse-chasers#tab-info">Eclipse Chasers</a>, perhaps the best-known eclipse experiment was the proof of Albert Einstein’s general theory of relativity. In the early 20th century this theory could only be tested during the minutes of totality, requiring a clear sky around the covered Sun so you could photograph the stars. </p>
<h2>Women in the field</h2>
<p>Accounts of well-known historic discoveries in astronomy might leave the impression this work was only undertaken by men. But in the late 19th and early 20th century, women in Australia already participated in astronomy as <a href="https://www.cambridge.org/core/journals/publications-of-the-astronomical-society-of-australia/article/making-visible-the-first-women-in-astronomy-in-australia-the-measurers-and-computers-employed-for-the-astrographic-catalogue/AD35E9CECEBC784E926D7B8F35E3D4E0">female “computers”</a> and amateur astronomers. They were deeply involved in scientific expeditions to view total solar eclipses, but it was not easy. </p>
<p>The living conditions were rough, in tents with poor amenities open to the weather, and little or no privacy. The months needed to travel on solar eclipse expeditions meant leaving family responsibilities, one of the reasons it was unusual to find women in the field. When women did participate, they were usually the wives and daughters of male astronomers. </p>
<figure class="align-right ">
<img alt="A young woman in a mortar board hat and gown." src="https://images.theconversation.com/files/516151/original/file-20230318-4441-paqzir.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/516151/original/file-20230318-4441-paqzir.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1033&fit=crop&dpr=1 600w, https://images.theconversation.com/files/516151/original/file-20230318-4441-paqzir.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1033&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/516151/original/file-20230318-4441-paqzir.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1033&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/516151/original/file-20230318-4441-paqzir.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1298&fit=crop&dpr=1 754w, https://images.theconversation.com/files/516151/original/file-20230318-4441-paqzir.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1298&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/516151/original/file-20230318-4441-paqzir.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1298&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Annie Louisa Virginia Dodwell (1870-1924) graduated with a Bachelor of Science from the University of Adelaide. Collection University of Adelaide. This image was taken with a group of other graduands around 1905. Enhanced.</span>
</figcaption>
</figure>
<p>The first Australian woman whose total solar eclipse observations were officially reported was Annie Louisa Virginia Dodwell. She had a Bachelor of Science from the University of Adelaide and gained astronomy knowledge working with her husband George Dodwell, the South Australian Government Astronomer.</p>
<p>Together, they organised the Adelaide Observatory expedition to Bruny Island in Tasmania for the 1910 total solar eclipse. The party arrived by ship and for a month they camped in tents in almost constant rain to prepare. The eclipse day was clouded, nonetheless Annie successfully recorded the change in temperature, the only science of value that was achieved. </p>
<p>In the following years she presented <a href="http://nla.gov.au/nla.news-page4558317">talks about astronomy</a>, published poems and participated in the <a href="https://www.iau.org/science/meetings/past/general_assemblies/87/">inaugural International Astronomical Union assembly</a> at the Vatican Observatory in 1922. She arranged the logistics for her husband’s total solar eclipse expedition later that year, during which she <a href="http://nla.gov.au/nla.news-page4558314">transcribed his observations</a> to the newspapers.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-century-ago-australia-was-ground-zero-for-eclipse-watchers-and-helped-prove-einstein-right-172605">A century ago, Australia was ground zero for eclipse-watchers – and helped prove Einstein right</a>
</strong>
</em>
</p>
<hr>
<h2>Seasoned eclipse chasers in the 1920s</h2>
<p>In 1922 an international team of astronomers, led by William Campbell, Director of Lick Observatory, and assisted by the Australian Navy, travelled to a remote location in Western Australia to confirm Einstein’s general theory of relativity during the September 21 total solar eclipse.</p>
<p>There were five women participating in this expedition: Elizabeth Campbell, Jean Chant with her daughter Elizabeth, Eleanor Adams and Mary Acworth Evershed. </p>
<figure class="align-center ">
<img alt="Four women in 1922 aboard a ship." src="https://images.theconversation.com/files/516172/original/file-20230319-5719-57kj8m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/516172/original/file-20230319-5719-57kj8m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=292&fit=crop&dpr=1 600w, https://images.theconversation.com/files/516172/original/file-20230319-5719-57kj8m.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=292&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/516172/original/file-20230319-5719-57kj8m.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=292&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/516172/original/file-20230319-5719-57kj8m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=366&fit=crop&dpr=1 754w, https://images.theconversation.com/files/516172/original/file-20230319-5719-57kj8m.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=366&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/516172/original/file-20230319-5719-57kj8m.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=366&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Four of the women who participated in the total solar eclipse expedition led by Lick Observatory to Wallal Downs on their way from Broome to Ninety Mile Beach, Western Australia, 1922. Left to right: Elizabeth Chant (1899-1982), Jean Chant (1870-1940), Mary Acworth Evershed (1867-1949), Elizabeth Ballard Campbell (1869-1961). Collection State Library Western Australia, 4131B/1/24. Colourised.</span>
<span class="attribution"><span class="source">State Library Western Australia</span></span>
</figcaption>
</figure>
<p>While they were the wives and daughter of respective male astronomers, each woman was a seasoned eclipse observer in her own right. They knew how to operate and use technical equipment and contributed substantially to reporting the scientific work.</p>
<p>Elizabeth Campbell organised the supplies and operated spectroscopic and photographic telescope equipment during the eclipse. Eleanor Adams worked with her husband on the large 12-metre eclipse camera. Jean Chant observed the shadow bands and changing brightness of the sky, and Elizabeth Chant operated a prism that polarised light.</p>
<p>Mary Acworth Evershed was an established expert in solar physics and worked alongside her husband, director of the Kodaikanal solar observatory in India. She photographed the spectra of the Sun’s corona. In 1896, on return to England, she published a pocket-sized Easy Guide to the Southern Stars with star maps of the constellations visible from the southern hemisphere. </p>
<figure class="align-center ">
<img alt="A man and a woman in tent adjusting a piece of equipment that has a circular mirror and pivots on one axis." src="https://images.theconversation.com/files/517483/original/file-20230326-1899-vtbhf0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/517483/original/file-20230326-1899-vtbhf0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=490&fit=crop&dpr=1 600w, https://images.theconversation.com/files/517483/original/file-20230326-1899-vtbhf0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=490&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/517483/original/file-20230326-1899-vtbhf0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=490&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/517483/original/file-20230326-1899-vtbhf0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=616&fit=crop&dpr=1 754w, https://images.theconversation.com/files/517483/original/file-20230326-1899-vtbhf0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=616&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/517483/original/file-20230326-1899-vtbhf0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=616&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Mary Acworth and John Evershed adjusting a problematic instrument called a coelestat used to track the Sun. Lick Observatory Photographs. Special Collections and Archives, University Library, UC Santa Cruz. Photograph: Ernest Brandon-Cremer.</span>
</figcaption>
</figure>
<h2>A long drive across the country</h2>
<p>On the other side of the continent, a very different eclipse expedition was organised by 21-year-old Miriam Chisholm with her school friend Frida Tindal. Chisholm’s father, Frank, drove them over 950 kilometres from Goulburn to southern Queensland.</p>
<p>They lost four days when their car was bogged in mud and almost didn’t make it to the line of totality. Thankfully, due to excellent time-keeping and navigation they had a successful eclipse. They drew the Sun’s corona, measured the temperature, observed how animals and birds became quiet and timed the shadow bands. <a href="http://articles.adsabs.harvard.edu/pdf/1924MmBAA..24...94C">Their report</a> is descriptive, inspiring and filled with detailed observations. It is still a useful guide on how to make the most of a total solar eclipse experience.</p>
<figure class="align-center ">
<img alt="Father and daughter stand in front of a car in 1922. He is drinking from a cup. A telescope is strapped to the side of the car." src="https://images.theconversation.com/files/516147/original/file-20230318-3576-mt1qvg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/516147/original/file-20230318-3576-mt1qvg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=405&fit=crop&dpr=1 600w, https://images.theconversation.com/files/516147/original/file-20230318-3576-mt1qvg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=405&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/516147/original/file-20230318-3576-mt1qvg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=405&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/516147/original/file-20230318-3576-mt1qvg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=509&fit=crop&dpr=1 754w, https://images.theconversation.com/files/516147/original/file-20230318-3576-mt1qvg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=509&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/516147/original/file-20230318-3576-mt1qvg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=509&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Miriam and Frank Chisholm with their eclipse-chasing car. You can see her telescope strapped to the side of the car. Courtesy History Goulburn. Photograph: Miriam Chisholm, self-timer. Colourised image.</span>
<span class="attribution"><span class="source">History Goulburn</span></span>
</figcaption>
</figure>
<p>On April 20 2023 a total solar eclipse will be visible from Exmouth in Western Australia. This is the first total solar eclipse in Australia since 2012, when thousands of people flocked to northern Queensland. I was there, and for two minutes and five seconds of totality, I experienced a beautiful “diamond ring” effect as the Moon totally covered the Sun, revealing its misty corona. </p>
<p>There are four more total solar eclipses in the next 17 years. Following in the footsteps of early 20th century eclipse chasers, large numbers of Australians will soon be able to share a total solar eclipse experience they will treasure, record and retell throughout their lives.</p><img src="https://counter.theconversation.com/content/200552/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Toner Stevenson is affiliated with the University of Sydney, Faculty of Arts and Social Sciences, School of Humanities.
She is currently Vice President of Sydney City Skywatchers, an amateur astronomy society, not-for-profit, and in voluntary capacity. The society was previously called the British Astronomical Association, NSW Branch. This society will be mentioned in the article. She is on the Board of the Australian National Committee of the International Council of Museums, voluntary role.
She is a co-author of the recently published 'Eclipse Chasers' book, the research for which informed this article.
</span></em></p>History might give you the impression astronomical discoveries were only done by men. But women were participating in scientific expeditions of eclipses too, even though it wasn’t easy.Toner Stevenson, Honorary history affiliate in the School of Humanities, Faculty of Arts and Social Sciences, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1726052022-01-05T19:09:56Z2022-01-05T19:09:56ZA century ago, Australia was ground zero for eclipse-watchers – and helped prove Einstein right<figure><img src="https://images.theconversation.com/files/437492/original/file-20211214-25-mcaved.jpg?ixlib=rb-1.1.0&rect=5%2C102%2C1697%2C1533&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:36._Solar_corona,_Australian_eclipse,_Sept._21,_1922_(22748022995).jpg">Ontario Picture Bureau/Wikimedia Commons</a></span></figcaption></figure><p>In 1922, Australia was even more remote from the rest of the world than it is today. But when it came to astronomy, that year it was the centre of everyone’s attention.</p>
<p>On September 21, the shadow of a <a href="https://theconversation.com/explainer-what-is-a-solar-eclipse-33019">total solar eclipse</a> would cross the entire continent, from Eighty Mile Beach in Western Australia, right through the outback, and out over the Pacific Ocean just south of the Queensland-New South Wales border.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/436295/original/file-20211208-149721-1hhv2a7.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Vintage newspaper eclipse map" src="https://images.theconversation.com/files/436295/original/file-20211208-149721-1hhv2a7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/436295/original/file-20211208-149721-1hhv2a7.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=452&fit=crop&dpr=1 600w, https://images.theconversation.com/files/436295/original/file-20211208-149721-1hhv2a7.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=452&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/436295/original/file-20211208-149721-1hhv2a7.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=452&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/436295/original/file-20211208-149721-1hhv2a7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=568&fit=crop&dpr=1 754w, https://images.theconversation.com/files/436295/original/file-20211208-149721-1hhv2a7.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=568&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/436295/original/file-20211208-149721-1hhv2a7.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=568&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Map published in the Argus newspaper, showing the eclipse track.</span>
<span class="attribution"><span class="source">Argus</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Astronomers came from the United States, Canada, New Zealand, India and Britain – journeying to places so remote that many Australians had never heard of them before their names started appearing in the press. </p>
<p>The scientists were there not just for the spectacle, but also in the hope their observations of the eclipse would validate Albert Einstein’s then-controversial theory of general relativity, postulated just seven years earlier. </p>
<p>Einstein’s <a href="https://theconversation.com/explainer-einsteins-theory-of-general-relativity-3481">theory</a>, broadly speaking, suggested gravity can bend the very fabric of space-time itself. One possible way to test this was to photograph the background of stars both before and during an eclipse. The Sun’s gravity should bend the light from the distant stars as it passes in front of them, causing them to appear in a slightly different position – and the eclipse would allow astronomers to make this observation by helpfully blotting out the Sun’s glare.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-einsteins-theory-of-general-relativity-3481">Explainer: Einstein's Theory of General Relativity</a>
</strong>
</em>
</p>
<hr>
<h2>War and weather</h2>
<p>The first world war prevented astronomers from investigating Einstein’s 1915 prediction. But a total solar eclipse on May 29 1919 offered the first decent chance to prove him right. Britain mounted two separate expeditions in the hope at least one of them could make the necessary observations. In <a href="https://www.worldscientific.com/doi/abs/10.1142/S0218271818430046">Sobral, Brazil</a>, the team led by Astronomer Royal Frank Dyson suffered equipment failure. But on the island of Principe off Africa’s west coast, Arthur Eddington, despite inclement weather, successfully photographed the event.</p>
<p>Dyson, after viewing Eddington’s photographic plates, pronounced “there can be no doubt that they confirm Einstein’s prediction”. But many sceptics remained unconvinced.</p>
<p>The next suitable eclipse was in Australia on September 21 1922. The famous Lick Observatory in California had used its fine 12-metre camera to photograph several previous eclipses, and director William Wallace Campbell was determined his observatory would solve “the Einstein problem” in Australia. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-what-is-a-solar-eclipse-33019">Explainer: what is a solar eclipse?</a>
</strong>
</em>
</p>
<hr>
<p>Campbell’s chosen location – Wallal, on the WA coast 320km south of Broome, was remote and almost inaccessible. But it had virtually no chance of cloud, and the eclipse there would last longest, offering a full five minutes of totality. </p>
<p>Shallow seas meant the expedition’s ships could not get close to shore, and instead had to ferry the equipment ashore at high tide with the help of local Indigenous people.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/437488/original/file-20211214-25-1s3kjo6.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Eighty Mile Beach" src="https://images.theconversation.com/files/437488/original/file-20211214-25-1s3kjo6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/437488/original/file-20211214-25-1s3kjo6.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=388&fit=crop&dpr=1 600w, https://images.theconversation.com/files/437488/original/file-20211214-25-1s3kjo6.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=388&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/437488/original/file-20211214-25-1s3kjo6.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=388&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/437488/original/file-20211214-25-1s3kjo6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=487&fit=crop&dpr=1 754w, https://images.theconversation.com/files/437488/original/file-20211214-25-1s3kjo6.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=487&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/437488/original/file-20211214-25-1s3kjo6.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=487&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Eighty Mile Beach at Wallal, during low tide.</span>
<span class="attribution"><span class="source">Brian Finlayson</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The Royal Australian Navy also played an essential role in transporting the heavy and delicate equipment to Wallal, where Campbell’s group, which also included Canadian and New Zealand astronomers, had set up camp near the telegraph station. </p>
<p>Also at Wallal were astronomers from the Perth Observatory, the Kodiakanal Solar Observatory in India, and a smaller private British expedition. The various teams made several practice runs, knowing they would get just one chance at the eclipse itself.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/437489/original/file-20211214-25-7j4z3.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Eclipse observation site at Wallal" src="https://images.theconversation.com/files/437489/original/file-20211214-25-7j4z3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/437489/original/file-20211214-25-7j4z3.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=388&fit=crop&dpr=1 600w, https://images.theconversation.com/files/437489/original/file-20211214-25-7j4z3.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=388&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/437489/original/file-20211214-25-7j4z3.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=388&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/437489/original/file-20211214-25-7j4z3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=488&fit=crop&dpr=1 754w, https://images.theconversation.com/files/437489/original/file-20211214-25-7j4z3.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=488&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/437489/original/file-20211214-25-7j4z3.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=488&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Location of the eclipse observation site, viewed seaward. Left of the vehicle are remains of Wallal Telegraph Station, including a well.</span>
<span class="attribution"><span class="source">Brian Finlayson</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Afterwards, having spent months studying the huge photographic plates created during the eclipse, Campbell telegraphed Einstein to tell him the observations were indisputable. A remote corner of Australia had played a pivotal role in proving one of the fundamental truths of the Universe.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/437490/original/file-20211214-13-1ikfssh.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Chart of star displacements from 1923 scientific paper" src="https://images.theconversation.com/files/437490/original/file-20211214-13-1ikfssh.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/437490/original/file-20211214-13-1ikfssh.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=577&fit=crop&dpr=1 600w, https://images.theconversation.com/files/437490/original/file-20211214-13-1ikfssh.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=577&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/437490/original/file-20211214-13-1ikfssh.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=577&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/437490/original/file-20211214-13-1ikfssh.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=725&fit=crop&dpr=1 754w, https://images.theconversation.com/files/437490/original/file-20211214-13-1ikfssh.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=725&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/437490/original/file-20211214-13-1ikfssh.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=725&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Star displacements observed during the 1922 eclipse, consistent with the movements predicted by Einstein’s theory.</span>
<span class="attribution"><span class="source">Campbell & Trumper/Lick Observatory Bulletin 1923</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Meanwhile, other astronomers and amateur enthusiasts right across Australia were turning their eyes heavenwards as the eclipse passed overhead. South Australia sent an expedition to Cordillo Downs in the state’s northeast, led by Government Astronomer George Dodwell. His remote journey, laden with bulky equipment, was an undertaking of heroic proportions. Yet now, Cordillo Downs is chiefly known for its historic woolshed. </p>
<p>In the eastern states travel was somewhat easier, and many of the public gathered in Goondiwindi on the Queensland-NSW border to watch the eclipse. Scientist, businessman and philanthropist <a href="https://adb.anu.edu.au/biography/grimwade-sir-wilfrid-russell-7054">Sir Wilfrid Russell Grimwade</a> organised a trip there from Melbourne; Sydney Observatory sent its astronomers; Sydney University mounted an expedition led by physicist <a href="https://adb.anu.edu.au/biography/vonwiller-oscar-ulrich-8932">Oscar Vonwiller</a> that also included <a href="https://adb.anu.edu.au/biography/pigot-edward-francis-8048">Father Edward Pigot</a>, president of the NSW branch of the British Astronomical Association. Queensland’s Governor, <a href="https://adb.anu.edu.au/biography/nathan-sir-matthew-7728">Sir Matthew Nathan</a>, motored out for the event, and locals came from miles around. </p>
<p>Twenty of Pigot’s fellow members of the British Astronomical Association opted to travel to nearby Stanthorpe, while special trains carried Brisbane residents to Sandgate for the viewing. The indefatigable scientist Reverend Skertchly travelled from Brisbane to Mount Tamborine, where he made many different observations and later described viewing the corona as an epiphany.</p>
<h2>Time for recognition</h2>
<p>Australians from all walks of life engaged with the eclipse. Wonderful photographic records exist of the event, as well as special brochures and copious newspaper coverage. Scientific enthusiasm was mingled with fun, bringing together not just astronomers but also schoolchildren, Indigenous peoples, outback camel drivers, and the wider community. </p>
<p>Yet, a century later, this extraordinary coming together of global and local people isn’t very well documented in the places it happened. In September 1972, Goondiwindi’s citizens marked the golden jubilee of the eclipse, but we are not aware of any formal plans to mark its centenary this year. </p>
<p>At Wallal, which is close to a large and popular caravan park on Eighty Mile Beach, there is no mention of the momentous observations that helped prove Einstein’s genius. Perhaps a commemorative plaque or installation there would be a fitting place to start.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/we-counted-20-billion-ticks-of-an-extreme-galactic-clock-to-give-einsteins-theory-of-gravity-its-toughest-test-yet-173157">We counted 20 billion ticks of an extreme galactic clock to give Einstein's theory of gravity its toughest test yet</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/172605/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>A total eclipse that travelled the full width of Australia in 1922 offered astronomers the chance to confirm Einstein’s theory of general relativity - and for the community to enjoy a rare spectacle.Brian Finlayson, Honorary Principal Fellow in the School of Geography, Earth and Atmospheric Sciences, The University of MelbourneRay Sumner, Geographer, California State University, Dominguez HillsLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1721592021-12-02T15:12:08Z2021-12-02T15:12:08ZTotal solar eclipse will bring 2 minutes of darkness to Antarctica’s months of endless daylight<figure><img src="https://images.theconversation.com/files/435218/original/file-20211202-19-wjnzm4.jpg?ixlib=rb-1.1.0&rect=25%2C10%2C3316%2C1888&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Natacha Pisarenko/AAP Image</span></span></figcaption></figure><p>The Sun hasn’t set in Antarctica since October. Earth’s southernmost continent is currently experiencing a long summer’s day, one that stretches from mid-October until early April. </p>
<p>But on Saturday December 4, darkness will sweep across the ice of West Antarctica. The Moon will pass directly in front of the Sun, blocking its light and producing a total solar eclipse. </p>
<p>The path of totality crosses the Argentine, British and Chilean Antarctic Territories (which consist of overlapping regions), as well as the unclaimed territory known as Marie Byrd Land. Areas along the path will experience almost 2 minutes of darkness in the otherwise months-long stretch of daylight. </p>
<p>Meanwhile, the southern tips of South America, Africa, Australia and New Zealand will see a fairly minor partial eclipse. For South America and Africa, the eclipse will be in the early morning; for Australia and New Zealand it will happen as the Sun is setting. </p>
<h2>The Moon’s goodnight kiss</h2>
<p>As the Sun sinks towards the horizon the Moon will appear to kiss the top-left of the Sun. Of all Australia’s capital cities, <a href="https://www.timeanddate.com/eclipse/in/australia/hobart?iso=20211204">Hobart</a> will see the largest eclipse, but even so only 11% of the Sun’s area will be covered. For <a href="https://www.timeanddate.com/eclipse/in/australia/melbourne?iso=20211204">Melbourne</a>, this drops to just 2%, while in <a href="https://www.timeanddate.com/eclipse/in/australia/canberra?iso=20211204">Canberra</a> it’s hardly visible – the Sun is crossing the horizon as a tiny eclipse occurs.</p>
<p>It’s a similar situation in New Zealand. <a href="https://www.timeanddate.com/eclipse/in/new-zealand/invercargill">Invercargill</a> will see 4% of the Sun obscured by the Moon, with the Moon passing by the Sun’s left side. But move further north to <a href="https://www.timeanddate.com/eclipse/in/new-zealand/queenstown">Queenstown</a> and the eclipse is barely visible for the setting Sun. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/433885/original/file-20211125-19-m582uh.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/433885/original/file-20211125-19-m582uh.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/433885/original/file-20211125-19-m582uh.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=176&fit=crop&dpr=1 600w, https://images.theconversation.com/files/433885/original/file-20211125-19-m582uh.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=176&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/433885/original/file-20211125-19-m582uh.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=176&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/433885/original/file-20211125-19-m582uh.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=221&fit=crop&dpr=1 754w, https://images.theconversation.com/files/433885/original/file-20211125-19-m582uh.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=221&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/433885/original/file-20211125-19-m582uh.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=221&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p>In fact, if you weren’t aware of it, you wouldn’t even know the eclipse was happening. It’s not until about 80% or more of the Sun is obscured before we notice any change in daylight.</p>
<h2>Star light, star bright</h2>
<p>Solar eclipses are one astronomical event that require special care to observe. Most importantly, never look at the Sun directly – even when it’s low on the horizon. </p>
<p>Be sure to protect your eyes by using specially designed <a href="https://astrovisuals.com/product/eclipse-glasses-4-pack/">eclipse glasses</a>. These glasses also allow you to see any sunspots that might be active. The Sun is currently moving from a quiet phase to an active one, as part of a cycle that <a href="https://www.nasa.gov/press-release/solar-cycle-25-is-here-nasa-noaa-scientists-explain-what-that-means">repeats every 11 years</a>. You can check websites such as <a href="https://www.spaceweather.com/">Spaceweather</a> to see what’s happening on the Sun’s surface right now. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-what-is-a-solar-eclipse-33019">Explainer: what is a solar eclipse?</a>
</strong>
</em>
</p>
<hr>
<p>Normally, the projection method is a great way to observe solar eclipses. This involves making a small hole in the bottom of a plastic cup or piece of cardboard. Then, with your back to the Sun, hold the cup so the sunlight passes through the hole onto a flat surface such as a piece of paper or a wall, projecting an image of the Sun on the surface. </p>
<p>But because this is such a minor eclipse and it will happen at sunset in eastern Australia, it may be hard to focus the Sun’s image in this way. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/433884/original/file-20211125-13-1dtt5c7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/433884/original/file-20211125-13-1dtt5c7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/433884/original/file-20211125-13-1dtt5c7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/433884/original/file-20211125-13-1dtt5c7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/433884/original/file-20211125-13-1dtt5c7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/433884/original/file-20211125-13-1dtt5c7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/433884/original/file-20211125-13-1dtt5c7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/433884/original/file-20211125-13-1dtt5c7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A great way to safely share a view of a solar eclipse.</span>
<span class="attribution"><span class="source">Sid/flickr</span></span>
</figcaption>
</figure>
<h2>The rarity of totality</h2>
<p>Solar eclipses are relatively rare experiences, because the Moon’s orbit is tilted by 5 degrees relative to Earth’s orbit around the Sun, so they don’t quite move in the same plane. However, roughly every six months the orbits align to produce a pair of eclipses – a <a href="https://theconversation.com/tonights-eclipse-moonrise-will-put-on-a-special-twilight-show-for-most-of-australia-172061">lunar eclipse at Full Moon</a>, followed by a solar eclipse at New Moon (as we are experiencing now), or vice versa. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/tonights-eclipse-moonrise-will-put-on-a-special-twilight-show-for-most-of-australia-172061">Tonight's 'eclipse moonrise' will put on a special twilight show for most of Australia</a>
</strong>
</em>
</p>
<hr>
<p>Lunar eclipses are seen by more people because everyone on the night side of the Earth during a lunar eclipse will see the event. Solar eclipses happen just as often, but they are seen by far fewer people because the shadow created by the Moon passing in front of the Sun covers a much smaller fraction of the Earth. </p>
<p>Furthermore, partial solar eclipses are difficult to observe and they pale in comparison to the experience of a total solar eclipse. While total solar eclipses happen roughly every 18 months being able to see totality is rarer still. </p>
<p>The Moon’s shadow as it crosses the Earth is only 100-260km wide, and you have to be located within that narrow path to see the totally eclipsed Sun. This is why eclipse-chasers travel the world to be in the right place at the right time. But when totality occurs in a remote location like Antarctica it’ll be mainly the penguins who get to see it.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/9Vp2jUQ4rNM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>The next total solar eclipse visible from Australia will happen in <a href="https://www.timeanddate.com/eclipse/solar/2023-april-20">April 2023</a>. The band of totality will just clip Australia near Exmouth at the tip of the North West Cape in Western Australia.</p>
<p>But many more Aussies and New Zealanders will get to see a total solar eclipse on <a href="https://www.timeanddate.com/eclipse/solar/2028-july-22">July 22 2028</a>. Totality will stretch across Australia, from the top of WA down through New South Wales, passing directly over Sydney. It will also cross the South Island of New Zealand, passing through Queenstown and Dunedin.</p><img src="https://counter.theconversation.com/content/172159/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tanya Hill 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>Penguins will have the best seat in the house as a total solar eclipse passes over Antarctica on December 4. Australia and New Zealand will experience a minor partial eclipse, but not a noticeable one.Tanya Hill, Honorary Fellow of the University of Melbourne and Senior Curator (Astronomy), Museums Victoria Research InstituteLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1623792021-06-08T19:48:32Z2021-06-08T19:48:32ZFour ways to enjoy a solar eclipse<figure><img src="https://images.theconversation.com/files/405052/original/file-20210608-135198-ht2ylu.jpg?ixlib=rb-1.1.0&rect=268%2C67%2C4975%2C3356&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/scientific-background-astronomical-phenomenon-full-total-258826640">Shutterstock/IgorZh</a></span></figcaption></figure><p>The kind of solar eclipses usually portrayed in films are total solar eclipses – a reasonably rare event. They’re likely what you think about when you hear the word eclipse. </p>
<p>A total eclipse is when the Moon and the Sun line up in the sky in such a way that the Moon blocks the entire face of the Sun – called totality. Somewhere on the Earth these occur approximately every 18 months. </p>
<p>But we can’t all experience totality every time as the shadow of the Moon tracks a narrow path over the surface of the Earth. Any given point on the Earth is only likely to experience this approximately <a href="https://www.space.com/25644-total-solar-eclipses-frequency-explained.html">once every 375 years</a>.</p>
<p>Being able to view a total solar eclipse strongly depends on your <a href="https://www.timeanddate.com/eclipse">location</a> and having cloudless skies (or at least patchy clouds). Even though totality is not very common, you’ll likely have many partial solar eclipses from your location over the years. If you’re lucky enough to be in the path of a total or partial eclipse, get prepared and <a href="https://theconversation.com/im-a-solar-eclipse-chaser-heres-what-to-expect-from-this-weeks-partial-eclipse-162361">know what to expect</a>. </p>
<p>In the UK, we’ll get to see a <a href="https://www.timeanddate.com/eclipse/in/uk">partial eclipse on June 10th 2021</a>. Here are a few suggestions of what to do during an eclipse.</p>
<p><strong>1. Notice the Moon blocking out the Sun’s light and heat</strong></p>
<p>During any eclipse, the blocking of the Sun’s light and heat means it’ll get darker and cooler. How dark and how cool depends on how much of the Sun is being blocked. In a partial eclipse greater than 50%, enough light can be blocked to give the appearance of dusk. </p>
<p>This can confuse the local wildlife. You may notice the birds fall quiet and bats might start to come out to feed, even though it could be the middle of the day.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/lunar-and-solar-eclipses-make-animals-do-strange-things-119748">Lunar and solar eclipses make animals do strange things</a>
</strong>
</em>
</p>
<hr>
<p>Depending on the time of year, you might want to bring a jumper or coat. The local temperature can drop several degrees. In 2001, a drop of 5°C <a href="https://www.weatherbell.com/eclipse-impact-on-weather">occurred in Zambia</a> during totality and in 1834 a 15°C difference was <a href="https://nationaleclipse.com/newspapers/gettysburg_12091834.html">reported</a>.</p>
<p><strong>2. Test Einstein’s theory of relativity</strong></p>
<p>Newton thought gravity was a force between two objects, but Einstein’s 1915 theory of general relativity relied on the idea that gravity causes spacetime to bend. This means massive objects like stars causes the path of light to bend as it passes them by.</p>
<p>The Sun is a massive object which, according to Einstein’s theory, would bend the light from distant stars as it passes in front of them. Normally the Sun is far too bright to notice this light. But, in the few dark minutes of a total eclipse, you can see the stars near the Sun.</p>
<p>Just over a <a href="https://www.thenakedscientists.com/articles/science-features/eddingtons-eclipse-experiment-1919-and-2017">100 years ago</a>, a man called Arthur Eddington set up an expedition to two locations. One team went to the West African island of Príncipe, and the other went to Sobral, Brazil. <a href="https://www.space.com/einstein-relativity-1919-solar-eclipse-100-years-ago.html">Taking photographs</a> of the eclipse from two locations allowed comparative measurements of the positions of stars to prove Einstein’s theory correct.</p>
<figure class="align-center ">
<img alt="A diagram showing how massive objects bend spacetime." src="https://images.theconversation.com/files/405095/original/file-20210608-144898-3u4luo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/405095/original/file-20210608-144898-3u4luo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=350&fit=crop&dpr=1 600w, https://images.theconversation.com/files/405095/original/file-20210608-144898-3u4luo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=350&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/405095/original/file-20210608-144898-3u4luo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=350&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/405095/original/file-20210608-144898-3u4luo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=440&fit=crop&dpr=1 754w, https://images.theconversation.com/files/405095/original/file-20210608-144898-3u4luo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=440&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/405095/original/file-20210608-144898-3u4luo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=440&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Gravity bends spacetime.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/gravity-general-theory-relativity-concept-earth-1027733020">Shutterstock/vchal</a></span>
</figcaption>
</figure>
<p><strong>3. Think about our ancestors</strong></p>
<p>Even if you didn’t know it was happening in advance, you wouldn’t be concerned by a total eclipse of the Sun. With our modern scientific understanding of the orbits of objects in our solar system, we’d understand why it was occurring. We can (and often do) let the many eclipses, especially partial ones, pass us by unnoticed. </p>
<p>Ancient scientists were conducting experiments about the size of the Earth, Sun and Moon around 2,000 years ago, <a href="https://spark.iop.org/collections/early-astronomical-measurements">experiments you can try yourself today</a>. Our ancestors didn’t have our modern understanding. </p>
<p>As such, cultures from all around the world made up <a href="https://www.timeanddate.com/eclipse/solar-eclipse-myths.html">stories</a> to <a href="https://theconversation.com/how-ancient-cultures-explained-eclipses-79887">explain</a> what was happening. <a href="https://www.history.com/news/historic-eclipses">Historical solar eclipses</a> have forced a truce between warring nations, scared a king to death and were generally regarded as <a href="https://theconversation.com/how-eclipses-were-regarded-as-omens-in-the-ancient-world-81248">omens</a>.</p>
<figure class="align-center ">
<img alt="A diagram of what happens during a solar eclipse." src="https://images.theconversation.com/files/405058/original/file-20210608-27-8570iw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/405058/original/file-20210608-27-8570iw.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=391&fit=crop&dpr=1 600w, https://images.theconversation.com/files/405058/original/file-20210608-27-8570iw.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=391&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/405058/original/file-20210608-27-8570iw.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=391&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/405058/original/file-20210608-27-8570iw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=491&fit=crop&dpr=1 754w, https://images.theconversation.com/files/405058/original/file-20210608-27-8570iw.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=491&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/405058/original/file-20210608-27-8570iw.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=491&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">What happens during a solar eclipse.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/solar-eclipse-diagram-1146598682">Shutterstock/Andramin</a></span>
</figcaption>
</figure>
<p><strong>4. Watch it happen – safely</strong></p>
<p>We’re living in a time on this planet where the distance of the Moon’s orbit means that the apparent size of the Sun and Moon are approximately the same in the sky. The Moon is very slowly moving away from the Earth, so total solar eclipses <a href="https://spaceplace.nasa.gov/total-solar-eclipse/en/">won’t always be enjoyed by our descendants</a>. </p>
<p>In the days leading up to the event, check the weather and note the time of the start, maximum point and end of the eclipse. </p>
<p>You can safely observe a partial or total eclipse of the Sun with <a href="https://www.timeanddate.com/eclipse/make-pinhole-projector.html">items from around the home</a> – homemade pinhole cameras or even a kitchen colander can be used. Never look directly at the Sun without specialist equipment as it can cause permanent eye damage. </p>
<p>One strange thing we don’t understand during a total eclipse are <a href="https://eclipse2017.nasa.gov/exploring-shadow-bands">shadow bands</a> – lines of light and dark that appear on the ground just before an eclipse. If you are in the path of totality, you could try to record any evidence of them.</p>
<p>Taking even just a few minutes of your time to notice and enjoy these <a href="https://britastro.org/observing">astronomical events</a> can help you feel more connected to the wider environment and your place on planet Earth.</p><img src="https://counter.theconversation.com/content/162379/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Samantha Rolfe 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>Test out scientific ideas, connect with your ancestors or just marvel at the beauty of nature.Samantha Rolfe, Lecturer in Astrobiology and Principal Technical Officer at Bayfordbury Observatory, University of HertfordshireLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1623612021-06-08T13:32:52Z2021-06-08T13:32:52ZI’m a solar eclipse chaser – here’s what to expect from this week’s partial eclipse<figure><img src="https://images.theconversation.com/files/405019/original/file-20210608-28272-13fnfl2.png?ixlib=rb-1.1.0&rect=40%2C19%2C1237%2C699&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Ryan Milligan</span>, <span class="license">Author provided</span></span></figcaption></figure><p>In December 2020, in the middle of a pandemic, I made the somewhat questionable decision to fly 11,200km from where I live in Belfast, Northern Ireland to Santiago, Chile. Then, I boarded a connecting two-hour flight and drove for a further two hours, just to experience two minutes and 20 seconds of darkness. </p>
<p>I followed the guidelines of both the UK and Chilean governments. I got COVID-compliant travel insurance; I took a PCR test 72 hours before arriving in Chile; I wore a mask for the 15-hour flight and had my temperature taken in every building I entered. I also risked getting stranded on the other side of the world the week before Christmas, as the UK was considering banning domestic flights from England to Northern Ireland. </p>
<p>You might wonder why I’d go through all of this. The answer? To witness the most spectacular sight in nature: a total solar eclipse. Despite my endeavour, the Chilean weather thwarted my efforts and cloud coverage denied me a glimpse of the Sun’s ethereal pearly atmosphere.</p>
<p>This was my tenth solar eclipse trip, having previously travelled to witness eight total eclipses (one of which I missed because of clouds) and one annular eclipse. This week, there’s no travelling necessary – an eclipse will be visible from where I live. But I’m not expecting this one to be dramatic, and you shouldn’t either. </p>
<figure class="align-center ">
<img alt="An image of a partial solar eclipse." src="https://images.theconversation.com/files/405021/original/file-20210608-144041-14u320b.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/405021/original/file-20210608-144041-14u320b.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/405021/original/file-20210608-144041-14u320b.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/405021/original/file-20210608-144041-14u320b.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/405021/original/file-20210608-144041-14u320b.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/405021/original/file-20210608-144041-14u320b.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/405021/original/file-20210608-144041-14u320b.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Thursday’s eclipse will look similar to this, but never look directly at the Sun.</span>
<span class="attribution"><span class="source">Ryan Milligan</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Seeing <a href="https://theconversation.com/solar-eclipse-a-rare-opportunity-to-bask-in-the-moons-shadow-38634">a solar eclipse</a> is a rare experience and one that drives eclipse chasers like me. Witnessing day turn to night, feeling the temperature plummet, watching birds go to roost, perhaps seeing mysterious shadow bands, feeling your hairs stand on end and the adrenaline pump through your veins for those precious few minutes is always, always worth it. </p>
<p>A total solar eclipse occurs when the Moon completely obscures the Sun. This happens because the Moon is about 400 times smaller than the Sun, but also 400 times closer, giving them the same apparent size in the sky. </p>
<h2>Annular eclipse</h2>
<p>Because the Moon’s orbit is not perfectly circular, it can sometimes appear slightly smaller than the Sun. When this alignment happens, we witness an annular eclipse – a “ring of fire” appears around the Moon because a halo of the solar disk is still visible. </p>
<p>In an annular eclipse, the temperature barely changes, the shadows behave as you’d expect and the corona remains hidden behind the glow of sunlight. On Thursday, June 10, an annular eclipse will be visible from parts of north-east Canada, Greenland and Siberia. In the UK and Ireland, we’ll see a partial solar eclipse. About 35% of the Sun will be blocked out by the moon as viewed from Northern Ireland and Scotland, decreasing to about 20% in south-east England. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/solar-eclipse-a-rare-opportunity-to-bask-in-the-moons-shadow-38634">Solar eclipse: a rare opportunity to bask in the moon's shadow</a>
</strong>
</em>
</p>
<hr>
<p>The event begins around 10am UK time and ends around 12:30pm, depending on location. Most people will be oblivious to what’s going on above their heads, even with clear skies. </p>
<p>To see the event at all, you will need specially approved solar eclipse glasses that reduce sunlight to safe levels. Looking directly at the Sun during anything other than totality – when the face of the Sun is completely obscured – can cause serious and irreparable eye damage. </p>
<figure class="align-center ">
<img alt="Someone holding a piece of paper with a crescent shape patch of light projected onto it." src="https://images.theconversation.com/files/405018/original/file-20210608-121132-1amk7cb.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/405018/original/file-20210608-121132-1amk7cb.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/405018/original/file-20210608-121132-1amk7cb.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/405018/original/file-20210608-121132-1amk7cb.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/405018/original/file-20210608-121132-1amk7cb.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/405018/original/file-20210608-121132-1amk7cb.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/405018/original/file-20210608-121132-1amk7cb.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">
<figcaption>
<span class="caption">A pinhole camera can project an eclipse onto paper.</span>
<span class="attribution"><span class="source">Ryan Milligan</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>But there are other safe, indirect ways to experience the event. Using a pinhole camera (two sheets of paper or card with a small hole punched in one of them) will allow you to project an image of the Sun onto the ground or a wall. </p>
<p>Similarly, anything with a tiny hole that can be used to create a shadow will do – a kitchen colander, the holes in a cracker, the spaces between the leaves in a tree, even cracks through gaps in your fingers can work with some patience. </p>
<h2>Eclipse chasing</h2>
<p>While Thursday’s event may prove underwhelming, even to those who see it under the best conditions, I’d urge anyone with a sense of adventure to attempt to witness a total solar eclipse at some point in their lives. </p>
<p>The next one will be on December 4 this year. Unfortunately, it will only be visible from Antarctica. Tours start from an eye-watering £15,000 – even I might have to give that one a miss. </p>
<p>I plan to travel to Indonesia in 2023 to see totality during a hybrid eclipse – total during part of the day, annular during the rest. The US, Mexico and Canada will experience another total solar eclipse in 2024, just seven years after one in 2017 that was only visible from the US, and was deemed to be <a href="https://theconversation.com/what-we-can-learn-from-the-2017-solar-eclipse-82171">the most-watched event in human history</a>. </p>
<p>Spain will host a total solar eclipse in 2026 that will again appear as a partial eclipse from the UK. But as early 20th-century eclipse chaser Rebecca Joslin said:</p>
<blockquote>
<p>Now eclipses are elusive and provoking things … visiting the same locality only once in centuries. Consequently, it will not do to sit down quietly at home and wait for one to come, but a person must be up and doing and on the chase.</p>
</blockquote><img src="https://counter.theconversation.com/content/162361/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ryan Milligan receives funding from the Science and Technology Facilities Council and NASA. </span></em></p>The vast majority of people will be oblivious to what’s going on above their heads.Ryan Milligan, Lecturer in Astrophysics, Queen's University BelfastLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1413272020-06-24T15:59:48Z2020-06-24T15:59:48ZComets, omens and fear: understanding plague in the Middle Ages<figure><img src="https://images.theconversation.com/files/343742/original/file-20200624-132972-1h40eg8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A comet depicted in medieval times in the Bayeux tapestry.</span> <span class="attribution"><a class="source" href="https://www.bayeuxmuseum.com/en/the-bayeux-tapestry/">Bayeux Museam</a>, <span class="license">Author provided</span></span></figcaption></figure><p>On August 30 2019, a comet from outside our solar system was observed by amateur astronomer <a href="https://www.nytimes.com/2019/12/07/science/interstellar-comet-2i-borisov.html">Gennady Borisov</a> at the MARGO observatory in Crimea. This was only the second time an interstellar comet had ever been recorded. <a href="https://www.jpl.nasa.gov/news/news.php?feature=7498">Comet 19 or C/2019 Q4 </a>, as it is now known, made its closest approach to the sun on December 8 2019, roughly coinciding with the <a href="https://www.who.int/csr/don/12-january-2020-novel-coronavirus-china/en/">first recorded human cases</a> of COVID-19.</p>
<p>While we know that this is merely coincidence, in medieval times authorities <a href="https://podcasts.apple.com/gb/podcast/episode-4-the-one-who-flies/id1517030516?i=1000476891328">regarded</a> natural phenomena such as comets and eclipses as portents of natural disasters, including plagues.</p>
<p>One of the most learned men of the early Middle Ages was the <a href="https://blogs.bl.uk/digitisedmanuscripts/2016/05/bede-the-greatest-hits.html">Venerable Bede</a>, an Anglo-Saxon monk who lived in Northumbria in the late seventh and early eighth centuries. In chapter 25 of his scientific treatise, <a href="https://www.library.wales/discover/digital-gallery/manuscripts/the-middle-ages/de-natura-rerum#?c=&m=&s=&cv=&xywh=-546%2C0%2C4483%2C3808">De natura rerum</a> (On the Nature of Things) , he <a href="https://www.liverpooluniversitypress.co.uk/books/id/38342/">describes comets</a> as “stars with flames like hair. They are born suddenly, portending a change of royal power or plague or wars or winds or heat”.</p>
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<h2>Plagues and natural phenomena</h2>
<p>Outbreaks of the <a href="https://www.who.int/news-room/fact-sheets/detail/plague">bubonic plague</a> were recorded long before the <a href="https://www.history.com/topics/middle-ages/black-death">Black Death</a> of the 14th century. In the 6th century, a plague spread from Egypt to Europe and lingered for the next 200 years. At the end of the seventh century, the Irish scholar <a href="https://www.birmingham.ac.uk/Documents/college-artslaw/CMR1900/CMR1900/Sample-entry-Adomnan-of-Iona.pdf">Adomnán, Abbot of Iona</a> wrote in book 42 of his <a href="https://www.jstor.org/stable/44479625?seq=1#metadata_info_tab_contents">Life of St Columba</a> of “the great mortality which twice in our time has ravaged a large part of the world”. The effects of this plague were so severe in England that, according to Bede, the kingdom of Essex <a href="https://www.britannica.com/topic/Ecclesiastical-History-of-the-English-People">reverted to paganism</a>.</p>
<p>The <a href="http://asc.jebbo.co.uk">Anglo-Saxon Chronicle records</a> that 664 “the sun grew dark, and in this year came to the island of Britain a great plague among men (‘micel man cwealm’ in Anglo Saxon)”. The year 664 held great significance for the English and Irish churches: a great meeting (or synod) was held in Whitby in Northumbria to <a href="https://www.newadvent.org/cathen/15610a.htm">decide</a> whether the English church should follow the Irish or Roman system for calculating the date of Easter. By describing the occurrence of an eclipse and plague in the same year as the synod, Bede makes this important event in the English Church more memorable and meaningful.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/343714/original/file-20200624-132965-v4o6bz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/343714/original/file-20200624-132965-v4o6bz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/343714/original/file-20200624-132965-v4o6bz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/343714/original/file-20200624-132965-v4o6bz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/343714/original/file-20200624-132965-v4o6bz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/343714/original/file-20200624-132965-v4o6bz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/343714/original/file-20200624-132965-v4o6bz.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">In the Middle Ages, comets like 2019’s C/2019 Q4 signalled a calamitous event on earth to come.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/2I/Borisov#/media/File:Comet-2IBorisov-HubbleST-20191016_(cropped).png">NASA, ESA & D. Jewitt (UCLA)</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Plague and medieval religion</h2>
<p>In the Middle Ages, occurrences like plague and disease were thought of as expressions of God’s will. In the Bible, God uses natural phenomena to punish humankind for sin. In the Book of Revelation 6:8, for example, pestilence is <a href="https://www.sacred-texts.com/bib/dou/rev.htm">described</a> as one of the signs of Judgement Day. Medieval scholars were aware that some plagues and diseases were spread through the air, as <a href="https://www.liverpooluniversitypress.co.uk/books/isbn/9781781382936/">explained</a> by the seventh-century scholar <a href="https://www.britannica.com/biography/Saint-Isidore-of-Sevilla">Isidore of Seville</a> in chapter 39 of his De natura rerum (On the Nature of Things): </p>
<blockquote>
<p>Pestilence is a disease spreading widely and infecting by its contagion whatever it touches. When plague (‘plaga’) smites the earth because of mankind’s sins, then from some cause, that is, either the force of drought or of heat or an excess of rain, the air is corrupted.</p>
</blockquote>
<p>Bede based his On the Nature of Things on this work by Isidore. In a discussion of plague in the Old English version of Bede’s <a href="https://www.medievalists.net/2015/02/old-english-translation-bedes-historia-ecclesiastica-gentis-anglorum-historical-cultural-context/">Ecclesiastical History</a> we find a reference to the “an-fleoga”, meaning something like “the one who flies” or “solitary flier”. This same idea of airborne disease is a feature of Anglo-Saxon medicine. One example comes from an Old English poem we call a <a href="https://anglosaxonpoetry.camden.rutgers.edu/the-metrical-charms/">metrical charm</a>, which combines ancient Germanic folklore with Christian prayer and ritual. In the <a href="https://heorot.dk/woden-9herbs.html">Nine Herbs Charm</a>, the charmer addresses each herb individually and invokes its power over disease:</p>
<blockquote>
<p>This is against poison, and this is against the one who flies,</p>
<p>this is against the loathsome one that travels throughout the land …</p>
<p>if any poison come flying from the east,</p>
<p>or any come from the north,</p>
<p>or any from the west over the nations of men,</p>
<p>Christ stood over the disease of every kind. </p>
</blockquote>
<p>As well as fearing plague, medieval scholars attempted to pinpoint its origins and carefully recorded its occurrence and effects. Like us, they used whatever means they could to protect themselves from disease. But it is clear medieval chroniclers presented historical events as part of a divine plan for humankind by linking them with natural phenomena like plagues and comets.</p><img src="https://counter.theconversation.com/content/141327/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Marilina Cesario works for Queen's University Belfast. She received funding from British Academy, Royal Society, Leverhulme Trust and Marie Curie.. </span></em></p><p class="fine-print"><em><span>Francis Leneghan works for the University of Oxford. </span></em></p>In medieval times natural phenomena, such as comets and eclipses, were regarded as portents of natural disasters, including plagues.Marilina Cesario, Senior Lecturer, School of Arts, English and Languages, Queen's University BelfastFrancis Leneghan, Associate Professor of Old English, University of OxfordLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1278192019-12-25T21:47:26Z2019-12-25T21:47:26ZWatch the Moon hide the Sun from northern Australia<figure><img src="https://images.theconversation.com/files/307366/original/file-20191217-164458-1f1zbjd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Moon passes in front of the Sun during this eclipse at Lake Bolac, Victoria, April 29, 2014.</span> <span class="attribution"><span class="source">Phil Hart</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>A partial solar eclipse will occur across northern Australia on December 26. During the afternoon, the Moon will pass in front of the Sun, partially blocking the Sun’s bright light.</p>
<p>The eclipse will take place north of Geraldton (WA), Alice Springs (NT) and Townsville (QLD). These towns will barely witness the eclipse, as from their vantage point the Moon just skims past the Sun’s outer limb. </p>
<p>Further north, the Moon will hide more of the Sun. For Australia, Darwin will experience the greatest eclipse, with up to 31% of the Sun’s area blocked by the Moon. </p>
<p>However, there won’t be any noticeable effects to let you know that the eclipse is occurring. The daylight will appear just as bright – it doesn’t begin to dim until around 80% or more of the Sun is blocked out. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/307364/original/file-20191217-164429-1hdwfax.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/307364/original/file-20191217-164429-1hdwfax.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=578&fit=crop&dpr=1 600w, https://images.theconversation.com/files/307364/original/file-20191217-164429-1hdwfax.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=578&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/307364/original/file-20191217-164429-1hdwfax.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=578&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/307364/original/file-20191217-164429-1hdwfax.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=726&fit=crop&dpr=1 754w, https://images.theconversation.com/files/307364/original/file-20191217-164429-1hdwfax.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=726&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/307364/original/file-20191217-164429-1hdwfax.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=726&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The partial solar eclipse on December 26 is visible from northern Australia.</span>
<span class="attribution"><span class="source">Xavier M. Jupier / Museums Victoria</span></span>
</figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/307367/original/file-20191217-164441-1ohesfh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/307367/original/file-20191217-164441-1ohesfh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/307367/original/file-20191217-164441-1ohesfh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=369&fit=crop&dpr=1 600w, https://images.theconversation.com/files/307367/original/file-20191217-164441-1ohesfh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=369&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/307367/original/file-20191217-164441-1ohesfh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=369&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/307367/original/file-20191217-164441-1ohesfh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=464&fit=crop&dpr=1 754w, https://images.theconversation.com/files/307367/original/file-20191217-164441-1ohesfh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=464&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/307367/original/file-20191217-164441-1ohesfh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=464&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p>To view the eclipse, be sure to take the necessary precautions to see it safely, without risking your eyesight. Most importantly, never look directly at the Sun. The timings and appearance of the eclipse for other locations can be found at <a href="https://www.timeanddate.com/eclipse/map/2019-december-26">timeanddate.com</a>.</p>
<h2>Ring of fire</h2>
<p>Australia’s experience of the eclipse is relatively modest because we lie on its outskirts. The main event is happening further north, in a narrow band stretching from Saudi Arabia, through southern India, Sri Lanka, Malaysia and out to the island of Guam.</p>
<p>View the eclipse from within that band (including the city of Singapore), and you will see a <a href="https://theconversation.com/explainer-what-is-a-solar-eclipse-33019">special type of solar eclipse</a> known as an annular solar eclipse. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/307372/original/file-20191217-164454-99qihv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/307372/original/file-20191217-164454-99qihv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/307372/original/file-20191217-164454-99qihv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=418&fit=crop&dpr=1 600w, https://images.theconversation.com/files/307372/original/file-20191217-164454-99qihv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=418&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/307372/original/file-20191217-164454-99qihv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=418&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/307372/original/file-20191217-164454-99qihv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=526&fit=crop&dpr=1 754w, https://images.theconversation.com/files/307372/original/file-20191217-164454-99qihv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=526&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/307372/original/file-20191217-164454-99qihv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=526&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Ring of Light in Outback Australia, Northern Territory, May 2013.</span>
<span class="attribution"><span class="source">Noeleen Lowndes</span></span>
</figcaption>
</figure>
<p>During an annular solar eclipse the Moon passes directly in front of the Sun - as it does during a total solar eclipse - but in this instance, the Moon is too small to fully obscure the Sun from view. </p>
<p>Instead of eclipsing or hiding the Sun, the Moon turns the Sun into a spectacular ‘ring of fire’ that encircles the dark Moon. </p>
<p>It’s a quirk of nature that Earth has a moon that is the right size (about 400 times smaller than the Sun) and is at the right distance (about 400 times closer to Earth than the Sun is) for a total solar eclipse to occur. </p>
<p>But since the Moon follows an elliptical orbit around the Earth, its distance varies slightly throughout its monthly orbit. If the Moon happens to be at or near the most distant part of its orbit during a solar eclipse, then the Moon will appear slightly smaller in the sky leading to an annular solar eclipse. </p>
<h2>How to see the eclipse</h2>
<p>A way to see the eclipse - while protecting your eyesight - is to project an image of the Sun onto another surface. This also works as a great way to share the moment with others and to enable younger children to share in the experience.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/307354/original/file-20191217-164441-1xkpyy5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/307354/original/file-20191217-164441-1xkpyy5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/307354/original/file-20191217-164441-1xkpyy5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/307354/original/file-20191217-164441-1xkpyy5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/307354/original/file-20191217-164441-1xkpyy5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/307354/original/file-20191217-164441-1xkpyy5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/307354/original/file-20191217-164441-1xkpyy5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/307354/original/file-20191217-164441-1xkpyy5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Share the view, with this easy to make and effective pin-hole camera.</span>
<span class="attribution"><span class="source">Sid/flickr</span></span>
</figcaption>
</figure>
<p>Make a small hole in the bottom of a plastic cup (or piece of cardboard) and with your back towards the Sun, hold the cup so that sunlight passes through the hole and onto a flat surface such as a piece of paper or a wall. </p>
<p>The image of the Sun will be small and faint. But it is generally enough to show that the Sun is no longer a complete circle. It works especially well if you track the changing shape as the eclipse slowly progresses. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/307355/original/file-20191217-164437-1dfoui7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/307355/original/file-20191217-164437-1dfoui7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/307355/original/file-20191217-164437-1dfoui7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/307355/original/file-20191217-164437-1dfoui7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/307355/original/file-20191217-164437-1dfoui7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/307355/original/file-20191217-164437-1dfoui7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/307355/original/file-20191217-164437-1dfoui7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/307355/original/file-20191217-164437-1dfoui7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A colander is a ready to use pin-hole camera, creating many pretty images of the eclipsed Sun.</span>
<span class="attribution"><span class="source">John Lord/flickr</span></span>
</figcaption>
</figure>
<p>Specially designed <a href="http://www.astrovisuals.com.au/Glasses.html">eclipse glasses</a> can be used to look at the Sun directly as they block out most of the light. Make sure they fit well and there are no scratches or other signs of wear or tear. Also it’s important to remember (especially for children) to look away from the Sun before putting on or taking off the glasses. </p>
<p>Eclipse glasses can also be used to look for large <a href="https://theconversation.com/massive-sunspots-and-huge-solar-flares-mean-unexpected-space-weather-for-earth-83677">sunspots</a> – dark spots or blemishes on the Sun’s surface that are slightly cooler than their surroundings because of strong magnetism. These spots appear quite small but are typically larger than the Earth – an incredible reminder of just how big the Sun truly is. </p>
<p>However, don’t be surprised if you see a blank Sun with no spots at all. We are currently in a deep solar minimum. As I write, the Sun has had no sunspots for over a month. In fact, 2019 has broken the known sunspot record – more than 270 days this year have featured a blank Sun, without any spots. That’s more than any other year since the Space Age began. You can follow <a href="https://www.spaceweather.com/">spaceweather.com</a> to track the daily sunspot count.</p>
<h2>Save the date</h2>
<p>This is the third solar eclipse for the year. But while they happen fairly regularly, you must be in the right location to have the full experience. For any specific location, it can be years between partial solar eclipses or centuries can pass between total solar eclipses. </p>
<p>Some may remember the total solar eclipse that occurred over <a href="https://www.youtube.com/watch?v=j9_w1r8vArw">Melbourne in 1976</a> or the more recent one over <a href="https://vimeo.com/54017986">northern Queensland in 2012</a>. </p>
<p>Australia’s last annular eclipse was seen in <a href="https://www.youtube.com/watch?v=YE4jrp4sneo">Western Australia in 2013</a>.</p>
<p>The next total solar eclipse for Australia will occur in <a href="https://www.timeanddate.com/eclipse/map/2023-april-20">April 2023</a>. The band of totality will just clip Australia near Exmouth at the tip of the North West Cape in Western Australia. </p>
<p>However, the eclipse worth waiting for will occur on <a href="https://www.timeanddate.com/eclipse/map/2028-july-22">July 22, 2028</a>. Totality will stretch across Australia, from the top of Western Australia down through New South Wales, passing directly over Sydney. That will be an amazing sight to see.</p><img src="https://counter.theconversation.com/content/127819/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tanya Hill 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>On December 26 a solar eclipse will be visible from northern Australia, southern Asia and parts of the Middle East.Tanya Hill, Honorary Fellow of the University of Melbourne and Senior Curator (Astronomy), Museums Victoria Research InstituteLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1188402019-07-18T01:05:47Z2019-07-18T01:05:47ZHow big is the Moon? Let me compare …<figure><img src="https://images.theconversation.com/files/284040/original/file-20190715-173325-11n8cww.jpg?ixlib=rb-1.1.0&rect=183%2C115%2C1211%2C824&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The size of the Moon can be deceptive when viewed from Earth.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/ovi90/13196699704/">Flickr/Ovi Gherman</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>Even though we can see the Moon shining brightly in the night sky – and sometimes in daylight – it’s hard to put into perspective just how large, and just how distant, our nearest neighbour actually is.</p>
<p>So just how big <em>is</em> the <a href="https://solarsystem.nasa.gov/moons/earths-moon/overview/">Moon</a>?</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/DMdhQsHbWTs?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The Moon passing in front of Earth, captured by the Earth Polychromatic Imaging Camera (EPIC), more than a million kilometres away from our planet.</span></figcaption>
</figure>
<p>That answer isn’t quite as straightforward as you might think. Like Earth, the Moon isn’t a perfect sphere. Instead, it’s slightly squashed (what we call an oblate sphereoid). This means the Moon’s diameter from pole to pole is less than the diameter measured at the equator.</p>
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Read more:
<a href="https://theconversation.com/why-the-moon-is-such-a-cratered-place-118842">Why the Moon is such a cratered place</a>
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</p>
<hr>
<p>But the difference is small, just four kilometres. The equatorial diameter of <a href="https://nssdc.gsfc.nasa.gov/planetary/factsheet/moonfact.html">the Moon</a> is about 3,476km, while the polar diameter is 3,472km.</p>
<p>To see how big that is we need to compare it to something of a similar size, such as Australia.</p>
<h2>From coast to coast</h2>
<p>The distance from <a href="https://www.freemaptools.com/how-far-is-it-between-perth_-australia-and-brisbane-qld_-australia.htm">Perth to Brisbane, as the crow flies, is 3,606km</a>. If you put Australia and the Moon side by side, they look to be roughly the same size.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/284051/original/file-20190715-173360-1nn1to4.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/284051/original/file-20190715-173360-1nn1to4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/284051/original/file-20190715-173360-1nn1to4.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=542&fit=crop&dpr=1 600w, https://images.theconversation.com/files/284051/original/file-20190715-173360-1nn1to4.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=542&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/284051/original/file-20190715-173360-1nn1to4.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=542&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/284051/original/file-20190715-173360-1nn1to4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=681&fit=crop&dpr=1 754w, https://images.theconversation.com/files/284051/original/file-20190715-173360-1nn1to4.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=681&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/284051/original/file-20190715-173360-1nn1to4.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=681&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 vs Australia.</span>
<span class="attribution"><span class="source">NASA/Google Earth</span></span>
</figcaption>
</figure>
<p>But that’s just one way of looking at things. Although the Moon is about as wide as Australia, it is actually much bigger when you think in terms of surface area. It turns out the surface of the Moon is much larger than that of Australia.</p>
<p>The land area of Australia is some <a href="https://www.australia.gov.au/about-australia/our-country/the-australian-continent">7.69 million square kilometers</a>. By contrast, the surface area of the Moon is <a href="https://solarsystem.nasa.gov/moons/earths-moon/by-the-numbers/">37.94 million square kilometres</a>, close to five times the area of Australia. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/284052/original/file-20190715-173370-1n3nttf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/284052/original/file-20190715-173370-1n3nttf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/284052/original/file-20190715-173370-1n3nttf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=360&fit=crop&dpr=1 600w, https://images.theconversation.com/files/284052/original/file-20190715-173370-1n3nttf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=360&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/284052/original/file-20190715-173370-1n3nttf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=360&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/284052/original/file-20190715-173370-1n3nttf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=452&fit=crop&dpr=1 754w, https://images.theconversation.com/files/284052/original/file-20190715-173370-1n3nttf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=452&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/284052/original/file-20190715-173370-1n3nttf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=452&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 rising above Uluru: You’d need five Australias to cover the land mass of the Moon.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/jurek_durczak/11466759956/">Flickr/jurek d Jerzy Durczak</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<h2>How far is the Moon?</h2>
<p>Asking how far away is the Moon is another of those questions whose answer is more complicated than you might expect.</p>
<p>The Moon moves in an elliptical orbit around the Earth, which means its distance from our planet is constantly changing. That distance can vary by up to 50,000km during a single orbit, which is why the size of the Moon in our sky varies slightly from week to week.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/284236/original/file-20190716-173347-id8trq.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/284236/original/file-20190716-173347-id8trq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/284236/original/file-20190716-173347-id8trq.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=364&fit=crop&dpr=1 600w, https://images.theconversation.com/files/284236/original/file-20190716-173347-id8trq.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=364&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/284236/original/file-20190716-173347-id8trq.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=364&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/284236/original/file-20190716-173347-id8trq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=457&fit=crop&dpr=1 754w, https://images.theconversation.com/files/284236/original/file-20190716-173347-id8trq.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=457&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/284236/original/file-20190716-173347-id8trq.png?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"></a>
<figcaption>
<span class="caption">Notice the difference in size? The Moon viewed from Earth at perigee (closest approach at 356,700km on October 26 2007) and apogee (farthest approach at 406,300km on April 3 2007).</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Lunar_perigee_apogee.png">Wikimedia/Tomruen</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>The Moon’s orbit is also influenced by every other object in the Solar System. Even when all of that is taken into account, the distance answer is still always changing, because the <a href="https://www.bbc.com/news/science-environment-12311119">Moon is gradually receding from the Earth</a> as a result of the tidal interaction between the two. </p>
<p>That last point is something we’ve been able to better study as a result of the Apollo missions. The astronauts who visited the Moon <a href="https://science.nasa.gov/science-news/science-at-nasa/2004/21jul_llr">placed an array of mirror reflectors on its surface</a>. Those reflectors are the continual target of lasers from the Earth. </p>
<p>By timing how long it takes for that laser light to travel to the Moon and back, scientists are able to measure the distance to the Moon with incredible precision, and to track the Moon’s recession from Earth. The result? The Moon is receding at a speed of 38mm per year – or just under 4 metres per century.</p>
<h2>Drive me to the Moon</h2>
<p>Having said all that, the average distance between the Moon and Earth is 384,402km. So let’s put that into context.</p>
<p>If I were to drive from Brisbane to Perth, following the <a href="https://goo.gl/maps/bZ62An1cBz9944zh6">fastest route suggested by Google</a>, I would cover 4,310km on my road trip. That journey, driving across the breadth of our country, would take around 46 hours.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/284231/original/file-20190716-173376-1mwkrmn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/284231/original/file-20190716-173376-1mwkrmn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/284231/original/file-20190716-173376-1mwkrmn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/284231/original/file-20190716-173376-1mwkrmn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/284231/original/file-20190716-173376-1mwkrmn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/284231/original/file-20190716-173376-1mwkrmn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/284231/original/file-20190716-173376-1mwkrmn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/284231/original/file-20190716-173376-1mwkrmn.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">The full Moon rising over the Perth Hills, in Western Australia, in 2016.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/135630555@N04/22823086188/">Paean Ng/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>If I wanted to clock up enough kilometres to say that I’d covered the distance between the Earth and the Moon, I’d have to make that trip more than 89 times. It would take five-and-a-half months of driving, non-stop, assuming I didn’t run into any traffic jams on the way.</p>
<p>Fortunately, the Apollo 11 astronauts weren’t restricted to Australian speed limits. The command module Columbia took just three days and four hours to reach lunar orbit following its launch on July 16 1969.</p>
<h2>An eclipse coincidence</h2>
<p>The equatorial diameter of the <a href="https://solarsystem.nasa.gov/solar-system/sun/by-the-numbers/">Sun</a> is almost 1.4 million kilometres, which is almost exactly 400 times the diameter of the Moon. </p>
<p>That ratio leads to one of astronomy’s most spectacular quirks – because the distance between the Earth and the Sun (149.6 million kilometres) is almost (but not quite) 400 times the distance between the Earth and the Moon.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-what-is-a-solar-eclipse-33019">Explainer: what is a solar eclipse?</a>
</strong>
</em>
</p>
<hr>
<p>The result? The Moon and the Sun appear almost exactly the same size in Earth’s sky. As a result, when the Moon and the Sun line up perfectly, as seen from Earth, something wonderful happens – a total eclipse of the Sun.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/2lHb5ruGUyw?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The total solar eclipse seen from north Queensland in November 2012.</span></figcaption>
</figure>
<p>Sadly, such spectacular eclipses will eventually come to an end on Earth. Thanks to the Moon’s recession, it will one day be too distant to perfectly obscure the Sun. But that day will be a long time coming, with most estimates suggesting it will occur in something like 600 million years’ time.</p>
<h2>The moonwalkers</h2>
<p>While we’ve dispatched out robot envoys to the icy depths of the Solar System, the Moon remains the only other world on which humanity has walked.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/284252/original/file-20190716-173325-1pnn0bu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/284252/original/file-20190716-173325-1pnn0bu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/284252/original/file-20190716-173325-1pnn0bu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=619&fit=crop&dpr=1 600w, https://images.theconversation.com/files/284252/original/file-20190716-173325-1pnn0bu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=619&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/284252/original/file-20190716-173325-1pnn0bu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=619&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/284252/original/file-20190716-173325-1pnn0bu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=778&fit=crop&dpr=1 754w, https://images.theconversation.com/files/284252/original/file-20190716-173325-1pnn0bu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=778&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/284252/original/file-20190716-173325-1pnn0bu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=778&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Astronaut Buzz Aldrin was the second man to walk on the Moon and one of the few moonwalkers still alive today.</span>
<span class="attribution"><a class="source" href="https://solarsystem.nasa.gov/resources/840/apollo-11-buzz-aldrin/">NASA</a></span>
</figcaption>
</figure>
<p>Fifty years after that first adventure, the number of people to have walked on the Moon who are still alive is in sharp decline. <a href="https://solarsystem.nasa.gov/news/890/who-has-walked-on-the-moon/">Twelve people</a> have had that experience but, as of today, just four remain.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/five-ethical-questions-for-how-we-choose-to-use-the-moon-116801">Five ethical questions for how we choose to use the Moon</a>
</strong>
</em>
</p>
<hr>
<p>Vast as the Moon is, those 12 moonwalkers barely scratched the surface. Hopefully, in the coming years, we will return, to inspire a whole new generation and to continue humanity’s in-person exploration of our nearest celestial neighbour.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/284248/original/file-20190716-173351-17qv15a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/284248/original/file-20190716-173351-17qv15a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/284248/original/file-20190716-173351-17qv15a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=255&fit=crop&dpr=1 600w, https://images.theconversation.com/files/284248/original/file-20190716-173351-17qv15a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=255&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/284248/original/file-20190716-173351-17qv15a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=255&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/284248/original/file-20190716-173351-17qv15a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=320&fit=crop&dpr=1 754w, https://images.theconversation.com/files/284248/original/file-20190716-173351-17qv15a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=320&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/284248/original/file-20190716-173351-17qv15a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=320&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 over the Sydney Opera House.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/paulcarmona/15332847519/">Flickr/Paul Carmon</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure><img src="https://counter.theconversation.com/content/118840/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jonti Horner does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Just 12 people have walked on the Moon and they’ll know better than anyone just how big (or small) the place is. But we can make some comparisons with things on Earth to get a measure of the Moon.Jonti Horner, Professor (Astrophysics), University of Southern QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1197482019-07-03T09:53:01Z2019-07-03T09:53:01ZLunar and solar eclipses make animals do strange things<p>For most animals, the structure of their day – and indeed their year – depends on the light-dark cycle. These regular and rhythmic cycles in the length of days tell animals when they should be foraging, when they should be asleep, when it’s time to migrate and when it’s time to breed. Animals can tell all this from how many hours of daylight they experience, but the moon’s cycles also strongly influence their behaviour. </p>
<p>The lunar synodic cycle – the moon’s regular journey from full moon to full moon again over 28 nights – causes changes in the Earth’s magnetic field, the moon’s gravitational pull on Earth, and light levels at night. Many species can detect this and use it to synchronise their breeding. Mass spawning in corals sees tens of millions of eggs released at once on reefs to coincide with full or new moons. But what happens to animals when the moon or the sun does something unusual or unexpected, such as an eclipse?</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/282338/original/file-20190702-126364-1u79owm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/282338/original/file-20190702-126364-1u79owm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/282338/original/file-20190702-126364-1u79owm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/282338/original/file-20190702-126364-1u79owm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/282338/original/file-20190702-126364-1u79owm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/282338/original/file-20190702-126364-1u79owm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/282338/original/file-20190702-126364-1u79owm.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">A coral (<em>Acropora millepora</em>) releases egg and sperm bundles during the annual spawning event on the Great Barrier Reef, following the full moon in late November.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/stony-coral-acropora-millepora-releasing-eggsperm-1313639321?src=AIVLlM49KBxEArzJZIQueg-1-4&studio=1">Coral Brunner/Shutterstock</a></span>
</figcaption>
</figure>
<h2>Solar eclipses</h2>
<p>Of all the cosmic events, solar eclipses prompt perhaps the biggest change in animal behaviour. Puzzled animals that are active during the day head back to their nighttime abodes while nocturnal animals think they’ve overslept. A solar eclipse occurs when the sun, moon and Earth are aligned on the same axis so that the moon completely blocks the sun. Around the world, unusual incidences of behaviour are usually reported while everyone else is watching the eclipse. </p>
<p>Some spider species begin to <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1439-0310.1994.tb00878.x">break down their webs </a> during an eclipse, as they typically do at the end of the day. Once the eclipse has passed, they begin to rebuild them again, possibly lamenting the lack of rest in between. Similarly, <a href="https://www.jstor.org/stable/20023118?seq=1#metadata_info_tab_contents">fish and birds</a> that are active during the day head for their nighttime resting places, while nocturnal <a href="https://www.jstor.org/stable/30055414?seq=1#metadata_info_tab_contents">bats appear</a>, seemingly tricked by the sudden darkness. </p>
<p>Hippos in Zimbabwe were observed <a href="https://sciencing.com/animals-reaction-solar-eclipse-3503.html">leaving their rivers</a> during an eclipse, heading towards their nocturnal feeding grounds on dry land. Midway through their departure, the eclipse passed, daylight returned and the hippos aborted their efforts. The animals appeared agitated and stressed following the eclipse for the remainder of the day.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/282334/original/file-20190702-126364-qd7emn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/282334/original/file-20190702-126364-qd7emn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/282334/original/file-20190702-126364-qd7emn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/282334/original/file-20190702-126364-qd7emn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/282334/original/file-20190702-126364-qd7emn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/282334/original/file-20190702-126364-qd7emn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/282334/original/file-20190702-126364-qd7emn.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">Leaving in a hurry.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/hippopotamus-walking-out-water-hyacinth-weed-206714923?src=ULHVylvi3xkkcD9eyTMlbA-1-0&studio=1">Jez Bennett/Shutterstock</a></span>
</figcaption>
</figure>
<h2>The moon</h2>
<p>A lunar eclipse happens when the moon, Earth and sun are very closely aligned, with the Earth positioned between the two. As the moon passes directly behind us, Earth blocks sunlight from directly reaching the moon, causing a reddish glow to appear. These so-called “blood moons” can only occur when there is a full moon, so it’s difficult to separate the impacts that lunar eclipses have on animals compared to a standard full moon.</p>
<p><a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0012572">A study in 2010</a> discovered that Azara’s owl monkeys – a typically nocturnal species – stopped foraging in Argentina during a lunar eclipse as their world became suddenly darker. They may have struggled to see their food, or felt too unnerved to move safely through the trees. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/282337/original/file-20190702-126400-hcr1u9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/282337/original/file-20190702-126400-hcr1u9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/282337/original/file-20190702-126400-hcr1u9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/282337/original/file-20190702-126400-hcr1u9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/282337/original/file-20190702-126400-hcr1u9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/282337/original/file-20190702-126400-hcr1u9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/282337/original/file-20190702-126400-hcr1u9.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">Azara’s owl monkeys stop feeding during lunar eclipses.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Azara%27s_night_monkey#/media/File:Aotus_azarae_infulatus.jpg">Rich Hoyer/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Around three times a year, a “supermoon” occurs, which is when a full moon coincides with perigee – the point at which the moon is closest to the Earth. The moon’s distance to Earth varies throughout the month, because the moon’s orbit is not a perfect circle. During a perigee event, the moon is about 46,000 km closer to the Earth than during apogee – when the moon is furthest from Earth. </p>
<p>During a supermoon, light levels at night are around <a href="https://science.nasa.gov/science-news/science-at-nasa/2011/16mar_supermoon/">30% brighter</a> than at any point in the moon’s monthly cycle, and it appears much larger in the sky. <a href="https://onlinelibrary.wiley.com/doi/epdf/10.1002/ece3.5311">Our recent study</a> found that wild barnacle geese responded to these supermoon events while they over-winter in south-west Scotland. We fitted small devices to the animals <a href="https://www.int-res.com/articles/esr2010/10/n010p021.pdf">which measure their behaviour</a> and found that the geese’s heart rate and body temperature increased at night during supermoons, when typically at this time of day they’d be subdued.</p>
<p>The birds didn’t respond to “supermoon” events when the moon was hidden by heavy cloud and the night stayed quite dark. So it appears that, a bit like with humans, the bright light of a supermoon woke the geese up, causing their heart rate and body temperature to increase, potentially in preparation for daytime.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/282335/original/file-20190702-126382-m4o6oi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/282335/original/file-20190702-126382-m4o6oi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/282335/original/file-20190702-126382-m4o6oi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/282335/original/file-20190702-126382-m4o6oi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/282335/original/file-20190702-126382-m4o6oi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/282335/original/file-20190702-126382-m4o6oi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/282335/original/file-20190702-126382-m4o6oi.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">Blood moons – despite their foreboding name – underwhelm barnacle geese.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/full-moon-eclipse-maximum-1406765399?src=Lmv71dIAAj2RJUKVPPyhJA-1-1&studio=1">Justinas Vitkus/Shutterstock</a></span>
</figcaption>
</figure>
<h2>The lunar cycle and us</h2>
<p>For centuries, people have been fascinated about the relationship between human behaviour and the lunar cycle. Many folklores and fables were connected to our interactions with the moon, the most extreme example perhaps being that of mythical beasts such as werewolves. It isn’t too surprising then that previously the term “lunatic” – from the Latin “lunaticus”, meaning “of the moon” – was used to describe people deemed to be mentally ill, crazy or unpredictable, until 1930, when more appropriate and sensitive terms were introduced. </p>
<p>It was once believed that the lunar cycle influenced a range of strange changes to a person’s physiology and the behaviour of wider society, with everything from birth rate, fertility, epilepsy and overall argumentativeness thought to be influenced. Many still believe that incidences of violent crime and general disorder <a href="https://www.theguardian.com/uk/2007/jun/05/ukcrime">increase around the time of a full moon</a>.</p>
<p>A series of studies published in the <a href="https://psycnet.apa.org/doiLanding?doi=10.1037%2F0033-2909.97.2.286">late 1980s</a> found no evidence at all of any link between the lunar cycle and human behaviour. The moon’s influence on us might remain the stuff of legend, but the confusion it sows among wild animals is very real indeed.</p><img src="https://counter.theconversation.com/content/119748/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Steve Portugal 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>While the world gathers to see an eclipse, what’s the rest of nature doing?Steve Portugal, Reader in Animal Biology and Physiology, Royal Holloway University of LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/897722018-01-30T02:40:59Z2018-01-30T02:40:59ZFrom rocket launches to a crashing space station, we’re in for a huge year in space<figure><img src="https://images.theconversation.com/files/203923/original/file-20180130-170416-1d6g8ea.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Rocket Lab successfully launched its Electron rocket from the company's complex on the Māhia Peninsula in New Zealand.</span> <span class="attribution"><span class="source">Rocket Lab</span></span></figcaption></figure><p>A Blood Moon, a trip to the Moon and back for two explorers, a space station crashing to Earth and the launch of a new mission to find planets around other stars: these are just some of the exciting things to watch in space in 2018.</p>
<p>Elon Musk’s Space X also plans to launch one of the new Falcon Heavy rockets, the largest since the manned Moon landings. </p>
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Read more:
<a href="https://theconversation.com/the-next-full-moon-brings-a-lunar-eclipse-but-is-it-a-super-blood-blue-moon-as-well-that-depends-90320">The next Full Moon brings a lunar eclipse, but is it a Super Blood Blue Moon as well? That depends...</a>
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<p>The Blood Moon comes from the lunar eclipse on Wednesday night, which is also being claimed as a Blue Super Full Moon (<a href="https://theconversation.com/the-next-full-moon-brings-a-lunar-eclipse-but-is-it-a-super-blood-blue-moon-as-well-that-depends-90320">or is it?</a>)</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/203735/original/file-20180129-100912-1tbuzgx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/203735/original/file-20180129-100912-1tbuzgx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/203735/original/file-20180129-100912-1tbuzgx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/203735/original/file-20180129-100912-1tbuzgx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/203735/original/file-20180129-100912-1tbuzgx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/203735/original/file-20180129-100912-1tbuzgx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/203735/original/file-20180129-100912-1tbuzgx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/203735/original/file-20180129-100912-1tbuzgx.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">A Blood Moon - when the Moon turns red during a total lunar eclipse. The red comes from the sunrise and sunset here on Earth, continuing out into space and lighting up the Moon.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/feature/super-blue-blood-moon-coming-jan-31">NASA</a></span>
</figcaption>
</figure>
<p>All of Australia, plus most of Asia and the Pacific region, will be treated to this <a href="https://www.timeanddate.com/eclipse/globe/2018-january-31">spectacular lunar event on January 31</a>. If you miss it, don’t worry, you’ll get another total lunar eclipse on the <a href="https://www.timeanddate.com/eclipse/lunar/2018-july-27">night of July 27 and early morning hours of July 28</a>.</p>
<p>Unlike a Solar eclipse, you do not need any special equipment to see a lunar eclipse and it is safe to look at with your eyes.</p>
<p>Speaking of solar eclipses, Tasmania and southern parts of Victoria and South Australia will be treated to a <a href="https://www.timeanddate.com/eclipse/solar/2018-july-13">partial Solar Eclipse on July 13</a>.</p>
<h2>Goodbye Kepler, thanks for the Exoplanets!</h2>
<p>The <a href="https://www.nasa.gov/mission_pages/kepler/overview/index.html">Kepler Space telescope</a> was launched nearly nine years ago and has changed our view of the cosmos and our place in it, but its mission is coming to an end this year.</p>
<p>Kepler has confirmed around <a href="https://www.nasa.gov/kepler/discoveries">2,500 exoplanets</a> (planets orbiting other stars), with thousands more potential planets. It discovered the first <a href="https://www.nasa.gov/ames/kepler/nasas-kepler-discovers-first-earth-size-planet-in-the-habitable-zone-of-another-star">Earth-like planet in a habitable zone </a>, an area where water could exist as a liquid.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/203909/original/file-20180130-117708-k10ugz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/203909/original/file-20180130-117708-k10ugz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/203909/original/file-20180130-117708-k10ugz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=480&fit=crop&dpr=1 600w, https://images.theconversation.com/files/203909/original/file-20180130-117708-k10ugz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=480&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/203909/original/file-20180130-117708-k10ugz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=480&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/203909/original/file-20180130-117708-k10ugz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=603&fit=crop&dpr=1 754w, https://images.theconversation.com/files/203909/original/file-20180130-117708-k10ugz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=603&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/203909/original/file-20180130-117708-k10ugz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=603&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An artistic impression of NASA’s planet-hunting Kepler space telescope.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/ames/kepler/reborn-kepler-can-still-find-planets">NASA Ames/JPL-Caltech/T Pyle</a></span>
</figcaption>
</figure>
<p>Kepler also showed that <a href="https://phys.org/news/2017-06-kepler-taught-rocky-planets-common.html">rocky, potentially Earth-like and/or habitable planets are common</a> with potentially tens of billions (yes, billions with a b) existing in our galaxy alone.</p>
<p>After a failure of two reaction wheels (the things that help it point) in 2013, a new mission, <a href="https://www.space.com/25913-nasa-kepler-telescope-new-mission.html">K2</a>, was conceived. It was able to keep stable by using a combination of short thruster firings and using the Sun to steer it like a sail. </p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/googles-artificial-intelligence-finds-two-new-exoplanets-missed-by-human-eyes-89024">Google's artificial intelligence finds two new exoplanets missed by human eyes</a>
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<p>Kepler continued its exoplanet-finding quest, along with discoveries such as <a href="http://www.abc.net.au/news/science/2016-03-22/supernova-shockwave-spotted-in-space-for-first-time/7216942">shockwaves from exploding stars</a> and even picking up <a href="https://www.space.com/28386-ancient-alien-planets-discovery-kepler-444.html">sound waves deep in the heart of stars</a> (a technique called asteroseismology).</p>
<p>But this extra thruster firing is causing Kepler to use up its fuel, and it is due to run out sometime this year, which will cause NASA to put it into hibernation.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"906298481253302272"}"></div></p>
<p>Where one missions ends, a new one begins. The Transiting Exoplanet Survey Satellite (<a href="https://tess.mit.edu/">TESS</a>), is <a href="https://tess.gsfc.nasa.gov/launch.html">set to be launched between March and June</a>, aboard a SpaceX Falcon 9 rocket. If the stars align, we might even have overlap between these two exoplanet-discovering machines.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/203336/original/file-20180124-107953-wv910z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/203336/original/file-20180124-107953-wv910z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/203336/original/file-20180124-107953-wv910z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=478&fit=crop&dpr=1 600w, https://images.theconversation.com/files/203336/original/file-20180124-107953-wv910z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=478&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/203336/original/file-20180124-107953-wv910z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=478&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/203336/original/file-20180124-107953-wv910z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=600&fit=crop&dpr=1 754w, https://images.theconversation.com/files/203336/original/file-20180124-107953-wv910z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=600&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/203336/original/file-20180124-107953-wv910z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=600&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 conceptual image of TESS in space and its targets - planets orbiting other stars.</span>
<span class="attribution"><span class="source">NASA</span></span>
</figcaption>
</figure>
<h2>Rockets, rockets and more rockets</h2>
<p>The privatisation of space continued this year with the US-based Rocket Labs having its <a href="http://fortune.com/2018/01/21/rocket-lab-successful-launch/">first successful launch</a>, from a site across the Tasman in New Zealand.</p>
<p>SpaceX also had its <a href="https://www.theverge.com/2018/1/24/16841580/spacex-falcon-heavy-rocket-static-fire-first-launch">first static test of the new Falcon 9 Heavy</a>, the largest rocket since the <a href="https://www.nasa.gov/audience/forstudents/5-8/features/nasa-knows/what-was-the-saturn-v-58.html">Saturn V that took US astronauts to the Moon</a>. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"943420026593337344"}"></div></p>
<p>The Falcon 9 Heavy is <a href="https://www.space.com/39400-spacex-falcon-heavy-first-engine-test-on-pad.html">scheduled for a first launch in early February</a> where it will carry one of Musk’s Tesla Roadsters. We may even see an appearance of the company’s <a href="https://www.floridatoday.com/story/tech/science/space/2018/01/01/spacex-leases-cape-canaveral-home-crew-dragon/982606001/">Dragon 2</a> that will carry humans into space this year. SpaceX has already announced that <a href="https://www.nytimes.com/2017/02/27/science/spacex-moon-tourists.html">two people have paid to go on a tour around the Moon</a>.</p>
<p>It’s not just private companies exploring space, with <a href="https://gbtimes.com/china-to-attempt-more-than-40-space-launches-in-2018-including-long-march-5-and-lunar-far-side-missions">China aiming for 40 launches in 2018</a> alone.</p>
<h2>Exploring the small things in our Solar System</h2>
<p>The Moon is on the radar for both India and China. India’s <a href="https://www.businessinsider.com.au/india-moon-landing-chandrayaan2-2017-12">Chandrayaan-2 is set to land on the Moon</a> in March, while China’s Chang’e 4 will be its second lunar rover, <a href="https://www.theguardian.com/science/2017/dec/31/china-mission-to-far-side-of-the-moon-space-discovery">set to land on the far side of the Moon at the end of 2018</a>. First it will have to launch a special communication satellite, slated for June, to a position called L2, or a special point related to the Earth-Moon system that will allow for communications with Earth and the far side of the Moon.</p>
<p>While it is a bit early for New Year’s Eve 2018, NASA already has big plans. New Horizons, the probe that <a href="https://www.nasa.gov/feature/new-horizons-top-10-pluto-pics/">flew by Pluto in 2015</a> is set to swing past its second icy world, 2014 MU 69, on December 31. Little is known about 2014 MU 69, <a href="https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2486958">which is around 6.5 billion km from the Sun</a>, other than the fact that it might be <a href="https://www.space.com/37713-nasa-pluto-probe-flyby-target-two-objects.html">two objects instead of one</a> and that it needs a <a href="http://www.abc.net.au/news/science/2017-11-08/new-horizons-pluto-mission-next-target-mu69/9126564">better name</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/203340/original/file-20180124-107971-nayez3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/203340/original/file-20180124-107971-nayez3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/203340/original/file-20180124-107971-nayez3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/203340/original/file-20180124-107971-nayez3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/203340/original/file-20180124-107971-nayez3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/203340/original/file-20180124-107971-nayez3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/203340/original/file-20180124-107971-nayez3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/203340/original/file-20180124-107971-nayez3.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">Hubble Space Telescope Wide Field Camera 3 discovery images of 2014 MU69. Positions are shown by the green circles.</span>
<span class="attribution"><span class="source">NASA, ESA, SwRI, JHU/APL, and the New Horizons KBO Search Team</span></span>
</figcaption>
</figure>
<p>Asteroids are not forgotten in all of this space exploration. Japan’s <a href="http://global.jaxa.jp/projects/sat/hayabusa2/">Hayabusa-2</a> is set to arrive at asteroid 162173 Ryugu. It’s a new version of Hayabusa, which surveyed the asteroid 25143 Itokawa and took samples before returning back to Earth, <a href="https://www.cnet.com/news/probe-returns-to-earth-after-asteroid-landing/">landing near Woomera, South Australia in 2010</a>. </p>
<p>Likewise, NASA’s <a href="https://ww.nasa.gov/osiris-rex/">OSIRIS-REx</a> will arrive at the asteroid Bennu where it will <a href="http://www.nature.com/news/osiris-rex-spacecraft-blazes-trail-for-asteroid-miners-1.20486">extend an arm to drill down into the asteroid</a>, and return with samples, in what is the next step towards an <a href="http://www.watoday.com.au/wa-news/gold-water-and-platinum-australians-lead-the-way-towards-asteroid-mining-boom-20171203-gzxmol.html">asteroid mining</a> future.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/203342/original/file-20180124-107953-yl8c08.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/203342/original/file-20180124-107953-yl8c08.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/203342/original/file-20180124-107953-yl8c08.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/203342/original/file-20180124-107953-yl8c08.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/203342/original/file-20180124-107953-yl8c08.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/203342/original/file-20180124-107953-yl8c08.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/203342/original/file-20180124-107953-yl8c08.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/203342/original/file-20180124-107953-yl8c08.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An artist impression of OSIRIS-REx extending its arm down to the asteroid Bennu.</span>
<span class="attribution"><span class="source">NASA</span></span>
</figcaption>
</figure>
<h2>A falling space station</h2>
<p>If you were around in 1979 and happened to be in Western Australia, you might have a unique souvenir – <a href="http://www.abc.net.au/local/photos/2009/07/09/2621733.htm">part of the US space station Skylab</a>, which re-entered and crashed outside Esperance, WA.</p>
<p>If you’ve seen the 2013 movie <a href="http://www.imdb.com/title/tt1454468/">Gravity</a> (and a spoiler alert for those who haven’t!) you might remember the final scene in which Sandra Bullock’s character returns home by hijacking Tiangong-1, the Chinese space station. She returns safely, but the same can’t be said for Tiangong-1.</p>
<p>Well in March, we are set for a clash of <a href="http://www.abc.net.au/radio/canberra/programs/afternoons/scifivsreality-gravity/9158658">sci-fi against reality</a> when <a href="http://www.abc.net.au/news/2017-10-16/chinese-space-lab-tiangong-1-is-hurtling-towards-earth/9054228">Tiangong-1 comes back down to Earth</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/looking-up-a-century-ago-a-vision-of-the-future-of-space-exploration-89859">Looking up a century ago, a vision of the future of space exploration</a>
</strong>
</em>
</p>
<hr>
<p>You can <a href="http://www.satflare.com/track.asp?q=37820#TOP">track</a> its progress but in short, somewhere between +43 and -43 latitude (or half the Earth), it will re-enter and break apart. Currently, the likely potential (land) areas are around Central and South America, Northern Africa and the Mediterranean, and indeed Western Australia.</p>
<p>Like Skylab, there are likely to be large pieces that survive re-entry. Hopefully you are lucky to be in a position to see it with your eyes, but not so close that it lands on your house, as it’s unlikely to be covered by your insurance policy.</p>
<p>So that’s a summary of some of the things we’re expecting to happen this year. But as with all science, I’m just as excited for those discoveries that we do not know about that will happen in 2018.</p><img src="https://counter.theconversation.com/content/89772/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Brad E Tucker receives funding from the Australian Research Council. </span></em></p>There are plenty of astronomical things to watch out for this year beyond this week’s lunar eclipse, including new Moon landings and a space station falling back to Earth.Brad E Tucker, Astrophysicist and Outreach Astronomer, Australian National UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/828252017-08-22T19:18:03Z2017-08-22T19:18:03ZWhat blackout? How solar-reliant power grids passed the eclipse test<p>The total solar eclipse that captivated the United States this week was more than just a celestial spectacle (and a reminder to <a href="http://www.abc.net.au/news/2017-08-22/donald-trump-looks-at-eclipse-without-glasses/8830404">take care of your eyes</a>). It was also a valuable lesson in how to manage electricity grids when a crucial generation source – solar power, in this case – goes temporarily offline.</p>
<p>The last total solar eclipse to pass over the US was <a href="http://abcnews.go.com/US/back-1979-total-solar-eclipse/story?id=49310831">in 1979</a>, a year when President Jimmy Carter was in the midst of the energy crisis and struggling with ballooning oil prices. In response, he made a concerted shift to greater energy independence through alternative energy sources such as solar.</p>
<p>In 2017, almost the whole world is grappling with the transformation of the electricity industry and the move to renewable energy.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/scientist-at-work-why-this-meteorologist-is-eager-for-an-eclipse-80636">Scientist at work: Why this meteorologist is eager for an eclipse</a>
</strong>
</em>
</p>
<hr>
<p>Eclipses have – and always will have – a lot to teach us. While this eclipse <a href="https://www.ft.com/content/d5119962-868f-11e7-8bb1-5ba57d47eff7">did not cause major disruption to the US electricity network</a>, it gave system operators a better understanding of how future intermittencies can be managed. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/182901/original/file-20170822-22150-52997z.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/182901/original/file-20170822-22150-52997z.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/182901/original/file-20170822-22150-52997z.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=334&fit=crop&dpr=1 600w, https://images.theconversation.com/files/182901/original/file-20170822-22150-52997z.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=334&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/182901/original/file-20170822-22150-52997z.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=334&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/182901/original/file-20170822-22150-52997z.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=420&fit=crop&dpr=1 754w, https://images.theconversation.com/files/182901/original/file-20170822-22150-52997z.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=420&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/182901/original/file-20170822-22150-52997z.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=420&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The path of the eclipse, shown relative to the positions of major US solar power installations.</span>
<span class="attribution"><span class="source">US Energy Information Administration</span></span>
</figcaption>
</figure>
<p>Despite the rapid decline and rebound in solar power output during the event, operators were able to manage without a hitch. Their thankless task reminds us of the importance of having resilient and robust electricity systems with sufficient backup capacity.</p>
<p>Solar plants lost around half of their ability to generate electricity during the two and a half hours of the eclipse, dipping and rising almost three times faster than the average rate at which power stations can ramp their output up and down. The shortfall was covered largely by gas-fired power plants, and extra hydro capacity.</p>
<p>California faced a particularly tough challenge because of its relatively high level of renewable energy; last year 10% of the state’s electricity came from solar photovoltaic (PV) power.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/182918/original/file-20170822-3806-12dwcxr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/182918/original/file-20170822-3806-12dwcxr.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=408&fit=crop&dpr=1 600w, https://images.theconversation.com/files/182918/original/file-20170822-3806-12dwcxr.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=408&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/182918/original/file-20170822-3806-12dwcxr.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=408&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/182918/original/file-20170822-3806-12dwcxr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=512&fit=crop&dpr=1 754w, https://images.theconversation.com/files/182918/original/file-20170822-3806-12dwcxr.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=512&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/182918/original/file-20170822-3806-12dwcxr.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=512&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">California’s solar output during the eclipse.</span>
<span class="attribution"><span class="source">California ISO</span></span>
</figcaption>
</figure>
<p>Given the <a href="https://theconversation.com/au/topics/national-electricity-market-2810">recent scrutiny</a> on Australia’s <a href="https://theconversation.com/australias-energy-sector-is-in-critical-need-of-reform-61802">beleaguered electricity grid</a>, it makes sense to ask how our power system would fare if faced with the same challenge. Take a walk through almost any suburb and you’ll see dozens of solar panels glinting from roofs. How much have they destabilised our grid? Would we pass the eclipse test?</p>
<p>System managers and market operators such as the <a href="https://www.aemo.com.au/">Australian Energy Market Operator</a> already intricately balance demand and supply levels throughout the day, and must deal with unexpected outages at power stations, extreme weather events (think of <a href="https://theconversation.com/what-caused-south-australias-state-wide-blackout-66268">South Australia</a>), and increasingly predict how the share of intermittent generation from renewable resources will be matched and secured.</p>
<p>According to the <a href="https://www.cleanenergycouncil.org.au/cec.html">Clean Energy Council</a>, Australian renewables <a href="https://www.cleanenergycouncil.org.au/policy-advocacy/reports/clean-energy-australia-report.html">provided 17% of the country’s electricity generation in 2016</a>. In world terms that looks rather unimpressive. But this figure does not reflect the growing impact of behind-the-meter solar PV that is slowly but surely reducing reliance on grid electricity during the day. </p>
<p>As outlined in a previous <a href="https://theconversation.com/factcheck-qanda-is-australia-the-world-leader-in-household-solar-power-56670">FactCheck</a>, Australia has the highest proportion of households with PV systems on their roof of any country in the world, at over 15%. (However our total energy produced from solar is somewhat less than Germany, Italy, Belgium and Japan, which have a propensity for larger systems). </p>
<p>Of course, all this distributed solar adds to the complexity for utilities and grid operators, and underpins why we have technical rules and connection standards to ensure that households connecting individual systems to the grid do not cause unintended consequences for local network areas. As the forecasts for rooftop solar installations continue to be revised upwards, AEMO nevertheless <a href="https://www.aemo.com.au/Electricity/National-Electricity-Market-NEM/Planning-and-forecasting/Electricity-Forecasting-Insights/Key-component-consumption-forecasts/PV-and-storage">remains sanguine about the potential for grid disruption</a>:</p>
<blockquote>
<p>…it is technically feasible to integrate this amount of rooftop PV into the network over the forecast horizon, through a mix of market, network, and non-network (such as storage) solutions to address issues such as increasing variability in system demand, low daytime demand, and increased ramping at morning and afternoon electricity system peaks.</p>
</blockquote>
<p>Utilities themselves are acutely aware of the “non-negotiable social contract of keeping the lights on”, as mused by Frank Tudor, chief executive of Western Australia’s regional utility Horizon Power, in an <a href="https://www.linkedin.com/pulse/mondays-solar-eclipse-frank-tudor">opinion piece</a> written before the eclipse. The emboldened South Australian government may take further comfort in the fact that its newly minted <a href="http://www.afr.com/business/energy/electricity/solar-reserve-to-build-new-650m-solar-thermal-plant-in-sa-20170814-gxvu2m">150-megawatt Aurora Solar Energy Project</a> would come into its own during such weather interruptions (more often due to clouds than eclipses), with its capacity to store solar power in molten salt storage tanks, to be dispatched as required during peak periods.</p>
<h2>Lean and green machines</h2>
<p>The eclipse also underlines how crucial the innovations in technology and data analytics will be in ensuring that electricity grids can still operate seamlessly as the share of renewable energy grows.</p>
<p>We are seeing this already in many small, isolated power networks across the country, where <a href="https://horizonpower.com.au/our-community/news-events/news/wa-leads-the-way-in-energy-transformation/">microgrids</a>, particularly in coastal tourist towns with a proclivity for clean technology, are already pushing the limits of hosting capacity and driving utilities to explore big data solutions to assist with the integration of increased levels of solar PV.</p>
<p>One such example is the <a href="https://horizonpower.com.au/carnarvon-distributed-energy-resources-der-trial/">sky camera trial</a> being conducted in Carnarvon, Western Australia, that will track weather patterns and anticipate cloud cover to help with grid stability. The trial is using machine learning to help predict the impact of weather on the grid, and to balance the fluctuations with other energy sources, thus helping the network to withstand such events without losing reliability.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/five-things-the-east-coast-can-learn-from-wa-about-energy-76398">Five things the east coast can learn from WA about energy</a>
</strong>
</em>
</p>
<hr>
<p>With our energy systems becoming ever more distributed and decentralised, the US eclipse provides another of nature’s lessons on the need to be smart about creating resilient networks.</p>
<p>The next <a href="http://www.abc.net.au/news/2017-08-22/total-solar-eclipse-when-where-australia/8813250">total solar eclipse for Australia</a> will be in 2028, and will pass straight over Sydney. In the meantime, a <a href="https://www.timeanddate.com/eclipse/hybrid-solar-eclipse.html">hybrid eclipse</a> will cross Australia’s northwest in <a href="https://www.timeanddate.com/eclipse/solar/2023-april-20">April 2023</a>. </p>
<p>Time will tell how much of an impact these events will have on our power grids. But given the importance of electricity for our health, wealth, transport and so much more, let’s hope our system operators and policy makers aren’t blindsided.</p><img src="https://counter.theconversation.com/content/82825/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dev Tayal also works as a strategist for Horizon Power.</span></em></p>The solar eclipse offered electricity network operators a “live drill” in how to cope with fluctuating output from renewable energy. They passed with flying colours.Dev Tayal, Energy Researcher, Curtin UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/810672017-08-16T23:20:00Z2017-08-16T23:20:00ZHow to safely watch an eclipse: Advice from an astronomer<figure><img src="https://images.theconversation.com/files/181473/original/file-20170808-26021-1c1hxx.jpg?ixlib=rb-1.1.0&rect=35%2C0%2C1455%2C920&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A total solar eclipse will be visible across parts of the United States Aug. 21, treating amateur and professional astronomers alike to sights similar to this NASA's Solar Dynamics Observatory ultraviolet image of the moon eclipsing the sun on Jan. 31, 2014.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/sdomission/12240009064/in/photolist-jDBfg3-c2E1bq-dtBfWJ-dtvHND-c31tsQ-fK6r7i-p3CWN2-p3zyq3-pGZ1wS-pXgLpy-pH2M45-pZnpn8-pXgTbQ-pH3Cd7-s5MMYH-pZvjy1-pZviTU-pGWFJr-pXgK4s-pXgSzj-p3D4wH-pZcvmt-pZnzyk-pZnxjk-p3Cqpg-c2xmSf-6GZ5Pf-6GUVQ4-oU2ZbY-6GZ9uo-6GZBA2-6GUnbM-6H58jj-6H5raG-6GYFFy-6H1mrn-6GZgJ3-6H5hUC-6GZJmZ-6H4SYb-6GZCHF-6H1jW2-6GZjY3-6H5mYb-6H4Vwh-6H4Uhq-qNsbs1-89mqGm-6GZMbV-6H59P1/">(NASA)</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p>Everyone knows that you should not look at the sun!</p>
<p>Not with your naked eye, not with sunglasses and certainly not with binoculars or with a telescope. Our sun might be just an ordinary star, but it’s extremely close to us — about 269,000 times closer than the <a href="https://imagine.gsfc.nasa.gov/features/cosmic/nearest_star_info.html">next nearest star</a>. This makes the sun very, very bright.</p>
<p>Everyone knows that you should not look at the sun. But what about during an eclipse? This situation will confront us <a href="http://eclipse.aas.org">on Aug. 21</a>, when the entirety of North America, along with parts of South America, Africa, Europe and eastern Russia, will experience a solar eclipse.</p>
<p>For the vast majority of viewers, including anyone in any part of Canada, the eclipse will be a <a href="https://www.timeanddate.com/eclipse/partial-solar-eclipse.html">partial one</a>. This means that the moon will block out part of the face of the sun but leave the rest of it unchanged.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/181475/original/file-20170808-26048-o6es2t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/181475/original/file-20170808-26048-o6es2t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/181475/original/file-20170808-26048-o6es2t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/181475/original/file-20170808-26048-o6es2t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/181475/original/file-20170808-26048-o6es2t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/181475/original/file-20170808-26048-o6es2t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/181475/original/file-20170808-26048-o6es2t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/181475/original/file-20170808-26048-o6es2t.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">NASA’s Solar Dynamics Observatory saw a partial solar eclipse in space when it caught the moon passing in front of the sun on May 25, 2017.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/nasamarshall/35568871254/in/photolist-Wc6LdW-WNjGWq-pMH5pg-6H2N8P-bUewyv-97Gehi-cbVVVm-Wgbiyu-RRJNpz-c2ZUhU-yA7gAy-9ZGcuR-S297WM-97pycE-vhGtc-97py8J-c1aCmd-hDBUv-6HqTa5-6N8pS5-97ncbx-pMPDra-c2Hp5A-r2yLWw-8GrzH8-c2ABNC-dKAnj3-8GryAM-6H2YYW-c2BzP7-eTkScd-c2AnGw-dtdZj6-8GrykF-emmsJ-c2AmK9-8GuNfy-c2Cqxw-c2AmBN-8GuNJY-8GuKWf-8GuMfC-c2Az8C-c2LXFA-97mQhT-qHr81h-c2Arkw-c2Azjj-8NxqFU-c2AqXo">(NASA)</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>If you’re under <a href="https://eclipse.gsfc.nasa.gov/SEanimate/SEanimate2001/SE2017Aug21T.GIF">the path of the partial eclipse</a> — even somewhere where the sun is 99 per cent concealed — you still should not look at the sun with the unaided eye. Even one-hundredth of the sun’s normal brightness is enough to permanently damage your eyesight.</p>
<p>Instead, you can safely watch the action through special <a href="https://www.space.com/36941-solar-eclipse-eye-protection-guide.html">eclipse glasses</a> (make sure they’re <a href="https://eclipse.aas.org/eye-safety/iso-certification">ISO certified and from a reliable supplier</a>), through a simple <a href="https://www.jpl.nasa.gov/edu/learn/project/how-to-make-a-pinhole-camera/">home-made pinhole camera</a> or even by looking at the shadows cast by <a href="https://petapixel.com/2012/05/21/crescent-shaped-projections-through-tree-leaves-during-the-solar-eclipse/">tree leaves</a> or by a <a href="http://www.huffingtonpost.co.uk/2015/03/20/solar-eclipse-colander-_n_6908140.html">kitchen colander</a>.</p>
<p>For some lucky viewers in parts of <a href="http://eclipse2017.org/blog/2017/01/15/states-the-total-eclipse-touches/">14 U.S. states</a>, a total solar eclipse awaits on Aug. 21. This will be far more exciting than a mere partial eclipse. For maybe as long as two minutes, depending on your exact location, the sun will disappear completely behind the moon. The temperature will drop, the stars will come out, and the birds will think evening has come.</p>
<p>If you are under the path of the total eclipse, you’ll likely have more than an hour of partial eclipse both before and after the exciting moment of totality. During the partial phases, the usual rules apply: Wear your eclipse glasses or use your colander, but don’t look at the sun unaided!</p>
<p>However, when the time finally arrives and when the sky goes dark, it will finally be safe to look. Take off your glasses, stare at the sun with your unaided eyes, and soak up a remarkable cosmic moment.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/181476/original/file-20170808-26004-1qtloh3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/181476/original/file-20170808-26004-1qtloh3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=402&fit=crop&dpr=1 600w, https://images.theconversation.com/files/181476/original/file-20170808-26004-1qtloh3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=402&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/181476/original/file-20170808-26004-1qtloh3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=402&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/181476/original/file-20170808-26004-1qtloh3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=505&fit=crop&dpr=1 754w, https://images.theconversation.com/files/181476/original/file-20170808-26004-1qtloh3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=505&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/181476/original/file-20170808-26004-1qtloh3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=505&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Hinode satellite observed the sun’s corona during a total solar eclipse on July 22, 2009.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/nasamarshall/3749824749/in/photolist-6HmQfR-amTUw8-ffnGgr-c2KEsh-87puxz-uoX4dq-6GZssa-W33piE-6GXKhS-6GZKUc-USp1ay-6H4x5u-na8q4i-aTdLfT-6GUbft-c2Ah4G-6GZwRv-6GYR9h-c2AiB3-6GTKSM-voESN-6GZuCB-97whBh-6H4CHW-pKwfEf-6GVhxv-c2AhrE-c2AiY7-pMEk4M-hFGgPZ-6GZZFa-pMJAnw-pMqArp-bo72po-pMEjHr-qfriq-hFDv8-9ogkg7-c2Ynk5-6H52Go-pvdsTL-c2Ak3j-LLRtM-6GYNzS-c2AjRE-59vsFe-4ZKxAs-6GYTMo-hFGggK-6SFStG">(NASA/JAXA)</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>During the total eclipse, it is completely safe to look at the sun without any equipment at all. And what a sight it will be.</p>
<p>Revealed, just for a moment, will be <a href="https://www.exploratorium.edu/eclipse/what-to-see-during-eclipse#totality">the sun’s glorious corona</a>, the faint <a href="https://eclipse2017.nasa.gov/solar-corona">tendrils of ultra-hot gas</a> that stream off the sun’s blazing surface. This is not to be missed. If you leave your eclipse glasses on, you won’t see anything.</p>
<p>After a minute or two, the total eclipse will be over, the skies will lighten and special safety precautions must once again be taken. But those who experience totality will be left with memories of an otherwise hidden view of the Universe, a brief glimpse of our life-giving sun unlike any other.</p><img src="https://counter.theconversation.com/content/81067/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Bryan Gaensler receives funding from the Natural Sciences and Engineering Research Council of Canada and from the Canada Research Chairs Program. He is the Director of the Dunlap Institute for Astronomy and Astrophysics, which will be distributing its eclipse glasses free of charge at the Canadian National Exhibition and other events.</span></em></p>If you’ve ever wondered why you can look at a solar eclipse and why it can harm your eyes, the answer is in the sun’s rays.Bryan Gaensler, Director, Dunlap Institute for Astronomy and Astrophysics, University of TorontoLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/795532017-08-14T17:16:57Z2017-08-14T17:16:57ZTotal eclipse, partial failure: Scientific expeditions don’t always go as planned<figure><img src="https://images.theconversation.com/files/181829/original/file-20170811-13490-1ybkdxu.jpg?ixlib=rb-1.1.0&rect=415%2C944%2C5419%2C3587&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Have telescopes, will travel: English astronomers await an 1871 eclipse in India. </span> <span class="attribution"><span class="source">The Illustrated London News, 1872</span></span></figcaption></figure><p>For centuries, astronomers have realized that total solar eclipses offer a valuable scientific opportunity. During what’s called totality, the opaque moon completely hides the bright photosphere of the sun – its thin surface layer that emits most of the sun’s light. An eclipse allows astronomers to study the sun’s colorful outer atmosphere and its delicate extended corona, ordinarily invisible in the dazzling light of the photosphere.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/181868/original/file-20170813-13505-e765rp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/181868/original/file-20170813-13505-e765rp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/181868/original/file-20170813-13505-e765rp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/181868/original/file-20170813-13505-e765rp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/181868/original/file-20170813-13505-e765rp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/181868/original/file-20170813-13505-e765rp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/181868/original/file-20170813-13505-e765rp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/181868/original/file-20170813-13505-e765rp.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">With most of the sun’s light blotted out, an eclipse lets astronomers see some of its dimmer extended features.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/mission_pages/hinode/solar_020.html">NASA</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>But total solar eclipses are infrequent, and are visible only from a narrow path of totality. So eclipse expeditions require meticulous advance planning to ensure that astronomers and their equipment wind up in the right place at the right time. As the history of astronomy shows, things don’t always go according to plan for even the most prepared eclipse hunters.</p>
<h2>Into hostile territory, at the mercy of the map</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/181810/original/file-20170811-13476-18oro9s.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/181810/original/file-20170811-13476-18oro9s.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/181810/original/file-20170811-13476-18oro9s.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=821&fit=crop&dpr=1 600w, https://images.theconversation.com/files/181810/original/file-20170811-13476-18oro9s.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=821&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/181810/original/file-20170811-13476-18oro9s.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=821&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/181810/original/file-20170811-13476-18oro9s.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1032&fit=crop&dpr=1 754w, https://images.theconversation.com/files/181810/original/file-20170811-13476-18oro9s.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1032&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/181810/original/file-20170811-13476-18oro9s.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1032&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Samuel Williams was prepared to cross enemy lines to see his eclipse.</span>
<span class="attribution"><span class="source">New England magazine, 1895</span></span>
</figcaption>
</figure>
<p>Samuel Williams, the newly appointed professor of mathematics and natural philosophy at Harvard College, was eager to observe a total solar eclipse. He’d seen a <a href="https://www.jstor.org/stable/1005194?seq=1#page_scan_tab_contents">transit of Venus in 1769</a>, but had never had the chance to study the sun’s corona during an eclipse. According to his calculations, a total solar eclipse would be visible from Maine’s Penobscot Bay on Oct. 27, 1780. </p>
<p>But reaching Maine from Massachusetts would be something of a problem; the Revolutionary War was raging, and Maine was held by the British Army. The Massachusetts legislature came to Williams’ assistance; it directed the state’s Board of War to fit out a ship to convey the eclipse hunters. Speaker of the House John Hancock wrote to the British commander in Maine, requesting permission for the men of science to make their observations. When the astronomer-laden ship arrived at Penobscot Bay, Williams and his team were permitted to land but restricted to the island of Isleboro, three miles offshore from the mainland.</p>
<p>The morning of the big day was cloudless. As the calculated moment of totality approached, at half past noon, the excitement built. The sliver of uneclipsed sun became narrower and narrower.</p>
<p>Then, at 12:31 p.m., it started becoming wider and wider. Williams realized, to his frustration, that he wasn’t in the path of totality after all. They were 30 miles too far south.</p>
<p>After a subdued voyage back to Massachusetts, Williams tried to determine what had gone wrong. Some astronomers, at the time and in following centuries, suggested his calculations of the path of totality were inaccurate.</p>
<p>Williams, however, had a different explanation. In his report to the newly founded American Academy of Arts and Sciences, he blamed <a href="https://www.jstor.org/stable/25053743?seq=22#page_scan_tab_contents">bad maps</a>:</p>
<blockquote>
<p>“The longitude of our place of observation agrees very well with what we had supposed in our calculations. But the latitude is near half a degree less than what the maps of that country had led us to expect.”</p>
</blockquote>
<p>Since half a degree of longitude corresponds to 30 nautical miles, this could explain why Williams ended up too far south.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/181813/original/file-20170811-13451-whylzh.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/181813/original/file-20170811-13451-whylzh.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/181813/original/file-20170811-13451-whylzh.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=480&fit=crop&dpr=1 600w, https://images.theconversation.com/files/181813/original/file-20170811-13451-whylzh.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=480&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/181813/original/file-20170811-13451-whylzh.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=480&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/181813/original/file-20170811-13451-whylzh.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=603&fit=crop&dpr=1 754w, https://images.theconversation.com/files/181813/original/file-20170811-13451-whylzh.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=603&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/181813/original/file-20170811-13451-whylzh.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=603&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Williams’ illustrations in his report of the eclipse. ‘Baily’s Beads’ are visible in Fig. VII on the upper right.</span>
<span class="attribution"><span class="source">Memoirs of the American Academy of Arts and Sciences</span></span>
</figcaption>
</figure>
<p>Although Samuel Williams missed seeing a total eclipse, his expedition was not a total failure. While watching the narrow sliver of sun visible at 12:31, he noted it became “broken or separated into drops.” These bright drops, known today as Baily’s Beads, are the result of the sun’s light shining through valleys and depressions along the moon’s visible edge. They’re named in honor of astronomer Francis Baily; however, <a href="https://doi.org/10.1093/mnras/4.2.15">Baily saw and described the beads in 1836</a>, nearly 56 years after Williams observed them. </p>
<h2>Hard to observe with smoke in your eyes</h2>
<p>Almost a century later, in 1871, English astronomer <a href="https://en.wikipedia.org/wiki/Norman_Lockyer">Norman Lockyer</a> was eager to observe a total solar eclipse.</p>
<p>Three years earlier, he and French astronomer <a href="https://en.wikipedia.org/wiki/Pierre_Janssen">Jules Janssen</a> had independently measured the spectrum of the sun’s chromosphere; to their surprise, they found an emission line in the yellow range of the spectrum, not corresponding to any known element.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/181870/original/file-20170813-13505-sxs6cw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/181870/original/file-20170813-13505-sxs6cw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/181870/original/file-20170813-13505-sxs6cw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=179&fit=crop&dpr=1 600w, https://images.theconversation.com/files/181870/original/file-20170813-13505-sxs6cw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=179&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/181870/original/file-20170813-13505-sxs6cw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=179&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/181870/original/file-20170813-13505-sxs6cw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=225&fit=crop&dpr=1 754w, https://images.theconversation.com/files/181870/original/file-20170813-13505-sxs6cw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=225&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/181870/original/file-20170813-13505-sxs6cw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=225&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The spectrum of helium: the bright yellow line at a wavelength of 587 nanometers (nm) is the emission line seen by Janssen and Lockyer.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Helium_spectrum.jpg">NASA</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Lockyer boldly claimed that the emission line was from a new element that he named “helium,” after the sun god Helios. Realizing that eclipses offered a helpful opportunity to search for more undiscovered elements, <a href="http://www.sup.org/books/title/?id=1216">Lockyer became a strong advocate of eclipse expeditions</a>. He knew the total solar eclipse of Dec. 12, 1871 would pass across southern India and persuaded the British Association for the Advancement of Science to sponsor an expedition. Wishing to show that British rule in India was linked to scientific progress, the British government chipped in £2,000, and the P&O steamship company offered reduced fares to India for the eclipse hunters.</p>
<p>Lockyer’s voyage to India went smoothly. (This could not be taken for granted; in 1870, on his way to view an eclipse from Italy, Lockyer was aboard a ship that ran aground off the east coast of Sicily.) The team set up their instruments on a tower at Bekal Fort, on the southwest Indian coast. The morning of Dec. 12, 1871 was cloudless. Although Lockyer was suffering from a fever (and from the effects of the opium he was taking to treat it), he was ready.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/181819/original/file-20170811-13483-ubydnp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/181819/original/file-20170811-13483-ubydnp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/181819/original/file-20170811-13483-ubydnp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=711&fit=crop&dpr=1 600w, https://images.theconversation.com/files/181819/original/file-20170811-13483-ubydnp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=711&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/181819/original/file-20170811-13483-ubydnp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=711&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/181819/original/file-20170811-13483-ubydnp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=894&fit=crop&dpr=1 754w, https://images.theconversation.com/files/181819/original/file-20170811-13483-ubydnp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=894&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/181819/original/file-20170811-13483-ubydnp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=894&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 sketch of the scene at Bekal as the eclipse gets underway.</span>
<span class="attribution"><span class="source">The Illustrated London News, 1872</span></span>
</figcaption>
</figure>
<p>Then, during the initial phases of the eclipse, he noted odd activity in the region below the fort. Local inhabitants were gathering a huge pile of brushwood to fuel a bonfire; apparently, by creating a bright fire on Earth, they hoped to encourage the darkening sun to become bright again. Lockyer was alarmed; the column of smoke would have risen directly between him and the eclipsed sun, ruining his observations.</p>
<p>Fortunately, the local superintendent of police happened to be present; he summoned a squadron of policemen who put out the fire and dispersed the crowd. During the now smoke-free eclipse, Lockyer made valuable observations of the structure of the sun’s corona.</p>
<h2>To see an eclipse you must see the sun</h2>
<p>Jump ahead to the early 20th century. The English Astronomer Royal <a href="http://adsabs.harvard.edu/full/1939Obs....62..179S">Sir Frank Dyson</a> was eager to view a total solar eclipse. He didn’t have to travel far, since the eclipse of June 29, 1927 had a path of totality cutting across northern England, from Blackpool in the west to Hartlepool in the east. As an eminent figure in the scientific establishment and a renowned expert on eclipses, Dyson had no trouble in commanding financial support for his eclipse observations.</p>
<p>What he could not command, however, was the famously fickle English weather. During the month of June, northern England averages about seven hours of direct sunlight per day; however, this comes from a mix of weather that includes completely overcast days and completely cloudless days. Dyson didn’t know what to expect.</p>
<p>After checking the weather records along the predicted eclipse path, Dyson decided to observe from the Yorkshire village of Giggleswick. As he and his team prepared for the eclipse, the location choice initially seemed dubious; for two weeks before the eclipse, the sky was completely cloudy every afternoon, at the time of day when totality would occur on June 29.</p>
<p>Despite the grimly unpromising weather, crowds of hopeful people converged on the widely publicized eclipse path. Railway companies ran special excursion trains, towns along the path of totality sponsored “eclipse dances” and newspapers offered “<a href="http://collection.sciencemuseum.org.uk/objects/co509985/ecliptoglass-eclipse-viewer-eclipse-viewer">ecliptoglasses</a>” to subscribers. </p>
<p>In the end, unfortunately, most viewers along the eclipse path were disappointed. From the errant cloud that blocked the totally eclipsed sun from Blackpool Tower to the unbroken overcast sky at Hartlepool, the weather did not cooperate. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/181816/original/file-20170811-13490-2phty2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/181816/original/file-20170811-13490-2phty2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/181816/original/file-20170811-13490-2phty2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=466&fit=crop&dpr=1 600w, https://images.theconversation.com/files/181816/original/file-20170811-13490-2phty2.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=466&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/181816/original/file-20170811-13490-2phty2.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=466&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/181816/original/file-20170811-13490-2phty2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=586&fit=crop&dpr=1 754w, https://images.theconversation.com/files/181816/original/file-20170811-13490-2phty2.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=586&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/181816/original/file-20170811-13490-2phty2.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=586&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">View of the totality at Gigglesworth, taken by Frank Dyson and his team.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.1093/mnras/87.9.657">Plate 8, Report of the Expeditions from the Royal Observatory, Greenwich, to observe the Total Solar Eclipse of 1927 June 29. Astronomer Royal, Monthly Notices of the Royal Astronomical Society, Volume 87, Issue 9</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Happily for Frank Dyson, however, the town of Giggleswick was nearly the only location along the eclipse path that had clear skies during totality. The estimated <a href="http://articles.adsabs.harvard.edu/full/1999JBAA..109..117M">70,000 people who converged there</a>, following the lead of the astronomer royal, also benefited from Dyson’s good luck.</p>
<p>After the eclipse, <a href="https://www.theguardian.com/science/1927/jun/30/eclipse1">Dyson’s public statement</a> was, by British standards, positively bubbly:</p>
<blockquote>
<p>“The photographs have come out extremely well. A very clear and striking eclipse. Our observations went off very well indeed.” </p>
</blockquote>
<p>Despite the difficulties posed by weather… and smoky bonfires… and dodgy maps… astronomers have always persevered in their quest to view eclipses.</p><img src="https://counter.theconversation.com/content/79553/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Barbara Ryden does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>For centuries, scientists have known when and where eclipses will be visible. They pack their bags, head for the line of totality and hope for the best – which doesn’t always happen.Barbara Ryden, Professor of Astronomy, The Ohio State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/810682017-08-13T23:20:31Z2017-08-13T23:20:31ZEclipse of reason: Why do people disbelieve scientists?<figure><img src="https://images.theconversation.com/files/180803/original/file-20170802-23916-akvsh3.jpg?ixlib=rb-1.1.0&rect=990%2C767%2C3509%2C2229&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">People reject science such as that about climate change and vaccines, but readily believe scientists about solar eclipses, like this one reflected on the sunglasses of a man dangerously watching in Nicosia, Cyprus, in a 2015 file photo.</span> <span class="attribution"><a class="source" href="http://www.cpimages.com/fotoweb/cpimages_details.pop.fwx?position=2&archiveType=ImageFolder&sorting=ModifiedTimeAsc&search=eclipse%20and%20sunglasses&fileId=7ED4E565C8CEED2778801C7E3A1D5E69FE75CC55B658603987FEF24F300B62227BF497D18515FAB7978750CE214B0837D1853405FB9357B8528905964E23D81984317B4AD1BA45C0B1D1A0CEED4BE5A2E297922C28FCC5CFEB24C714341D0405379E78A1A7A8BD255CA8195352209C044EE57DF58AFDD91552F44FC49A03AD85BB6B54D41907D6E4">(AP Photo/Petros Karadjias)</a></span></figcaption></figure><p>If you’ve been paying attention, you know that on Aug. 21, we’re in for a special cosmic treat: the <a href="https://eclipse.aas.org/">Great American Eclipse</a> of 2017.</p>
<p>The moon’s shadow will track a 4,000-kilometre course across the continental United States from coast to coast, <a href="http://depoebayeclipse2017.com">beginning with Depoe Bay, Ore.</a>, and end after 93 minutes in <a href="http://www.myrtlebeachonline.com/opinion/opn-columns-blogs/bob-bestler/article154030414.html">McClellanville, S.C.</a>. As a result, tens of millions of Americans will be treated to that rarest of natural wonders: a total eclipse of the sun.</p>
<p>Canada, unfortunately, won’t experience a total eclipse, but <a href="http://globalnews.ca/news/3548728/canada-solar-eclipse-august-21/">the view will still be impressive</a>: The sun will be 86 per cent eclipsed in Vancouver, 70 per cent in Toronto, and 58 per cent in Montreal. Canadians who want to experience totality from the comfort of home will need to wait until <a href="https://weather.com/science/space/news/next-total-solar-eclipse-april-2024-north-america">April 8, 2024</a> (Hamilton, Montreal and Fredericton), <a href="https://www.timeanddate.com/eclipse/solar/2044-august-23">Aug. 23, 2044</a> (Edmonton and Calgary) or <a href="http://www.solar-eclipse.de/en/eclipse/detail/2079-05-01/">May 1, 2079</a> (Saint John and Moncton).</p>
<p>In the meantime, back here in 2017, everyone is focused on Aug. 21. Under the path of the eclipse, <a href="http://www.theleafchronicle.com/story/news/eclipse/2017/04/26/schools-close-events-plotted-out-solar-eclipse-clarksville/100930722/">schools will be closed</a>, traffic <a href="https://www.mnn.com/earth-matters/space/blogs/augusts-total-solar-eclipse-national-traffic-jam">will be a nightmare</a>, and hotel rooms at the Days Inn are on offer <a href="https://www.nytimes.com/2017/07/10/travel/where-to-see-the-total-eclipse-astronomy.html">for $1,600 a night</a>.</p>
<h2>Absolute faith in eclipse predictions</h2>
<p>What is remarkable among all this excitement and frenzy is the lack of “eclipse deniers.” Nobody doubts or disputes the detailed scientific predictions of what will happen.</p>
<p>I will be watching the eclipse from <a href="http://www.kentuckymonthly.com/events/total-solar-eclipse-viewing-party/">Simpson County, Ky.</a>, where I expect I will be joined by thousands of others, all of us knowing in advance that totality for us will begin at 1:26:44 p.m., and will end 141 seconds later. It is inconceivable to any of us that the predictions will be wrong by even a single second.</p>
<p>Not one person will argue beforehand that <a href="https://www.dailykos.com/story/2017/4/12/1652527/-Congressman-leaves-stage-to-a-chorus-of-boos-after-saying-the-jury-is-still-out-on-climate-change">the jury is still out</a> on eclipses, that scientists have <a href="http://www.snopes.com/2017/02/08/noaa-scientists-climate-change-data/">tampered with the data</a>, that eclipses <a href="http://rationalwiki.org/wiki/Moon_landing_hoax">are faked by NASA</a>, that exposing children to eclipses <a href="https://www.cdc.gov/vaccinesafety/concerns/autism.html">causes autism</a> or even that eclipses are <a href="https://twitter.com/realdonaldtrump/status/265895292191248385">a Chinese hoax</a>. Across the continent, there will be climate deniers, creationists, anti-vaxxers and flat-Earthers looking upwards through their <a href="https://www.space.com/36941-solar-eclipse-eye-protection-guide.html">eclipse glasses</a>, all soaking up this wondrous moment along with everyone else.</p>
<p>[<em>Editor’s note: Astrophysicist and popular science communicator Neil deGrasse Tyson also echoed this article’s core assertion while it was in editing.</em>]</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"895634473425014785"}"></div></p>
<p>This presents a puzzle: Why do people distrust or dispute so many aspects of science, but unanimously accept, without question, the ridiculously specific predictions on offer for every eclipse?</p>
<h2>Why the selective denial of science?</h2>
<p>One possible reason is that we’ve been right on eclipses every time before. But for most people, a total eclipse is a once-in-a-lifetime experience. Most people won’t have experienced such predictions first hand, and will have to take it on trust that what’s happened before for others will happen again for them.</p>
<p>Another explanation might be that, unlike the case for <a href="https://inconvenientsequel.tumblr.com/">climate change</a> or <a href="http://www.sbs.com.au/shows/jabbed">vaccinations</a>, the science behind eclipses is simple and uncontroversial. While it’s true that astronomers have been making reasonably accurate eclipse predictions <a href="http://www.reuters.com/article/us-greece-archaeology-antikythera-mechan-idUSKCN0YW0XQ">for thousands of years</a>, the required calculations are <a href="https://eclipse.gsfc.nasa.gov/SEmono/reference/explain.html">highly complex</a>, extending far beyond the mathematics covered in high school or even in many university courses. Most people would find it difficult to reproduce or confirm any of these eclipse predictions for themselves.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/181584/original/file-20170809-32165-ik43tp.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/181584/original/file-20170809-32165-ik43tp.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/181584/original/file-20170809-32165-ik43tp.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/181584/original/file-20170809-32165-ik43tp.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/181584/original/file-20170809-32165-ik43tp.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/181584/original/file-20170809-32165-ik43tp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/181584/original/file-20170809-32165-ik43tp.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/181584/original/file-20170809-32165-ik43tp.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Actress Jenny McCarthy, who has been a prominent advocate of the false belief vaccines are linked to autism, sought to win support from lawmakers at the White House Correspondents Association dinner in this 2008 file photo.</span>
<span class="attribution"><a class="source" href="http://www.cpimages.com/fotoweb/cpimages_details.pop.fwx?position=87&archiveType=ImageFolder&sorting=ModifiedTimeAsc&search=jenny%20and%20mccarthy&fileId=7ED4E565C8CEED275AEAE4A023E6F0DBFE75CC55B6586039E8D351704E8E44E52937675D73DB2F545E68D1DB30CCFF1E8B21ADCD35D58FA29D52DFBAF28E76D1F8678765B3CC966147B863EC252668E1E60CABB17DD3AB06B4EFF96039433083D412195A45FA1418AA81C56FBE14091F03D99C08F02C911AB6180BBD75C2E46A">(AP Photo/Jose Luis Magana)</a></span>
</figcaption>
</figure>
<p>The more likely answer is that eclipses are not a threat. There is nothing at stake. Eclipses do not endanger <a href="https://www.edf.org/card/7-ways-global-warming-affecting-daily-life">our way of life</a> or our <a href="https://thinkprogress.org/heres-what-climate-change-will-do-to-the-american-economy-in-7-charts-e9d15a1ea6a5">standard of living</a>. Nobody fears that eclipses might have <a href="https://www.theguardian.com/environment/2011/feb/15/stern-review">economic implications</a>, could <a href="https://answersingenesis.org/big-bang/does-the-big-bang-fit-with-the-bible/">challenge our belief system</a> or <a href="https://avn.org.au/making-an-informed-choice/why-the-avn/">threaten our children</a>. There are no anti-eclipse <a href="http://www.tobaccotactics.org/">lobby groups</a> trying to set the narrative, and there are thus no well-funded <a href="http://www.ucsusa.org/center-for-science-and-democracy/sugar-coating-science.html">advertising campaigns</a> or <a href="http://rationalwiki.org/wiki/Soon_and_Baliunas_controversy">scientific studies</a> that aim to raise doubts in our minds or to subtly shape our thinking.</p>
<h2>Laws of science</h2>
<p>Eclipses are agenda-free. The science — and the resulting <a href="https://www.youtube.com/watch?v=iG9GdfL_ToU">extraordinary experience</a> — are left to speak for themselves.</p>
<p>The problem is that we don’t get to pick and choose what scientific facts or consensuses are controversial, and which are not. The same strict laws of science are everywhere.</p>
<p>So if you’re comfortable putting down your non-refundable deposit for your eclipse hotel, if you let a steel tube flying at 30,000 feet carry you to a town under the path of totality, if on the morning of Aug. 21 you check the weather forecast hoping for clear skies, if you pay for breakfast with your credit card, and if that afternoon you snap a picture of the eclipse with your smartphone, then you have staked your bank balance, your August vacation and your very life on the fact that science is testable and reproducible, and that faulty theories can’t withstand extended scrutiny and testing.</p>
<p>Total solar eclipses are a strange <a href="https://blogs.scientificamerican.com/life-unbounded/the-solar-eclipse-coincidence/">cosmic coincidence</a> and a remarkable, awe-inspiring experience. But they are also a profound reminder that when the emotions, money and politics are stripped away, none of us, at our core, are science deniers.</p><img src="https://counter.theconversation.com/content/81068/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Bryan Gaensler receives funding from the Natural Sciences and Engineering Research Council of Canada and from the Canada Research Chairs Program.</span></em></p>People universally believe scientists’ solar eclipse calendars, but vaccine warnings or climate predictions are forms of science that strangely do not enjoy equivalent acceptance.Bryan Gaensler, Director, Dunlap Institute for Astronomy and Astrophysics, University of TorontoLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/821712017-08-10T08:14:19Z2017-08-10T08:14:19ZWhat we can learn from the 2017 solar eclipse<figure><img src="https://images.theconversation.com/files/181212/original/file-20170807-29295-pk07yg.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">名古屋太郎/wikimedia</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>If you’ve never seen a solar eclipse before, you should make an effort to witness the <a href="https://eclipse.gsfc.nasa.gov/SEgoogle/SEgoogle2001/SE2017Aug21Tgoogle.html">breathtaking event</a> on August 21. While only people in the US will be able to see the total eclipse – in which the moon completely blocks the light from the sun – those living in parts of South America, Africa and Europe should be able to see at least a partial solar eclipse.</p>
<p>Solar eclipses occur when the <a href="https://theconversation.com/explainer-what-is-a-solar-eclipse-33019">moon passes between the Earth and the sun</a> so that it blocks part or all of the sunlight as viewed from a particular location on our planet. Earth is the only planet in the solar system <a href="https://theconversation.com/when-the-sun-goes-dark-5-questions-answered-about-the-solar-eclipse-81308">where this can happen</a> in this way. This is because of the moon’s size and its relative distance from the sun – when viewed from the Earth, it can identically cover the bright solar disc to reveal the tenuous, wispy outer atmosphere of the star (called the solar corona). </p>
<p>An eclipse does not happen every time the moon travels around the Earth. This is because its orbit has a slight inclination (about five degrees) relative to our planet’s journey around the sun. However when aligned correctly, the result is an awesome, emotional experience. Once the eclipse has begun, the moon continues to eat its way across the blazing sun before darkness falls, the temperature drops and the sky is dominated by a radiant crown around the moon. It happens approximately every 18 months.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/179226/original/file-20170721-28515-1ep69w1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/179226/original/file-20170721-28515-1ep69w1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/179226/original/file-20170721-28515-1ep69w1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=408&fit=crop&dpr=1 600w, https://images.theconversation.com/files/179226/original/file-20170721-28515-1ep69w1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=408&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/179226/original/file-20170721-28515-1ep69w1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=408&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/179226/original/file-20170721-28515-1ep69w1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=513&fit=crop&dpr=1 754w, https://images.theconversation.com/files/179226/original/file-20170721-28515-1ep69w1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=513&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/179226/original/file-20170721-28515-1ep69w1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=513&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">During an eclipse the sun’s corona becomes visible to observers on Earth.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/sites/default/files/thumbnails/image/white_light_corona.jpg">NASA</a></span>
</figcaption>
</figure>
<p>On August 21, the moon’s shadow will travel west to east, touching land at Lincoln Beach, Oregon at 09:05 Pacific Daylight Time <a href="http://eclipse2017.nasa.gov/eclipse-live-stream">before speeding across</a> North America at up to 1km per second and finally exiting close to Charleston, South Carolina, at 16:09 Eastern Daylight Time. The longest total eclipse will occur close to the town of Carbondale, Illinois – lasting about two minutes and 40 seconds. </p>
<p>Anywhere within the 110km wide path of the eclipse, observers will be able to see the sun completely covered. Outside of that, sky-watchers will still see a partial eclipse with decreasing percentages of the sun’s surface covered as one moves away from this narrow corridor. It is estimated that over 12m Americans live in the path of the total eclipse itself and another 200m people within a day’s drive of it. This is science engagement on an unprecedented scale and is likely to be the most orchestrated eclipse viewing event ever undertaken.</p>
<h2>Digital deluge</h2>
<p>Social media activity has been increasing for months now, building up the anticipation to be part of this rare event. Expect Twitter, Facebook, Snapchat, Flickr and Instagram to be swamped with eclipse pictures during and after the event. In fact, the eclipse should be one of the most digitally recorded events ever, which could be of use to scientists. The <a href="http://eclipse2017.nso.edu/citizen-cate/">Citizen CATE</a> (Continental-America Telescopic Eclipse) experiment aims to capture images of the inner solar corona using a network of more than 60 telescopes operated by citizen scientists, high school groups and universities. </p>
<p>Similarly, the <a href="https://eclipsemega.movie/">Eclipse Mega-movie</a> is asking observers to use their app to upload eclipse images along the path of totality to produce an expanded and continuous film of the total eclipse as it crosses the country. Both of these experiments will produce unique data-sets of the <a href="http://www.oxfordreference.com/view/10.1093/oi/authority.20110803122316167">white light corona</a>, a region that is usually impossible to observe because the exceptionally bright solar disc hides it from view. We will be able to examine like never before the detailed structure of the solar corona and how it is dragged out into space by the solar wind.</p>
<p>There is also a big focus on education. A top priority is making sure that people know how to safely view the eclipse. Looking directly at the sun <a href="http://gizmodo.com/5926497/what-happens-when-you-stare-at-the-sun">is unsafe</a> except during that brief period of the total eclipse. It is vitally important that only special solar filters, <a href="https://eclipse2017.nasa.gov/safety">such as certified eclipse glasses</a>, are used. Unfiltered cameras, telescopes, binoculars or other optical devices concentrate the solar rays and are a definite no-go in regard to eye safety. If no filters are available, it is best to use a pinhole camera to project the eclipse indirectly.</p>
<p>It is also important to take advantage of the amazing opportunity to inform a huge population about the science behind the event. There are thousands of astronomy-oriented events, parties even, being hosted along the path of totality.</p>
<h2>New science?</h2>
<p>Scientists are equally excited. Eleven NASA and <a href="http://www.noaa.gov/">NOAA</a> satellites, high-altitude balloons, hundreds of ground-based telescopes and even the International Space Station will all take advantage of this unique shadow-chase across the surface of the Earth. However, it is not just looking up at the moon and sun that is important. Total eclipses also provide us with an unprecedented opportunity to examine our own planet under quite unusual conditions.</p>
<p>NASA says that observers across several states will measure the radiant energy from the sun into the Earth’s atmosphere from the ground as well as from space. This should provide new insights into how the incident solar energy in our atmosphere changes when particles, clouds and in this case the moon, prevents sunlight from reaching the surface of the planet.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/jzftVMQ78KU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>I will be fortunate enough to be part of a four-hour live online telecast of the eclipse from Carbondale via NASA’s video podcast <a href="https://www.nasa.gov/multimedia/podcasting/nasaedge/index.html">EDGE</a>. This will include interviews with scientists and live panel questions, high-resolution sun images and a balloon launch. As a solar physicist who can only usually observe the solar corona from space by satellite instrumentation, it is special to be able to glimpse the corona with the (protected) naked eye for a brief time.</p>
<p>One interesting part to all this is the fact that the US gets another chance in seven years to maximise the opportunities that the eclipse brings. </p>
<p>It is said that one of the longlasting legacies of the Apollo missions to the moon is the number of American scientists today who were inspired to be engineers and scientists. Though this solar eclipse is science engagement in a different manner, the end goal is the same – bringing about not just a greater appreciation of the Earth, and solar or lunar research, but also sparking a desire in many young people to be the science leaders of the future.</p><img src="https://counter.theconversation.com/content/82171/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robert William Walsh receives funding from the Science and Technology Facilities Council, UK.</span></em></p>The eclipse will be one of the most digitally recorded events ever. Here’s how to be part of it.Robert William Walsh, Professor of Solar Physics, University of Central LancashireLicensed as Creative Commons – attribution, no derivatives.