Dead Planets Society is a podcast that takes outlandish ideas about how to tinker with the cosmos – from snapping the moon in half to causing a gravitational wave apocalypse – and subjects them to the laws of physics to see how they fare. Listen on Apple, Spotify or on our podcast page.
A total solar eclipse is one of the most incredible cosmic events we can witness from Earth – but they can also beinconvenient. Any particular location only experiences a solar eclipse about once every few hundred years or so, and travelling to the path of totality isn’t always feasible.
In this episode of Dead Planets Society, hosts Leah Crane and Chelsea Whyte are joined by astronomer Bruce Macintosh at the University of California, Santa Cruz, in their attempts to fix this problem and conjure up a total solar eclipse that is accessible to all.
Natural solar eclipses occur when the moon passes in front of the sun, casting a shadow on Earth’s surface. To create an artificial eclipse, our hosts will have to put something else between Earth and the sun. A relatively small sunshade could work, but it would have to be fairly close to Earth’ssurface to block out the entire sun – and to stay that close, it would need to orbit at extraordinary speeds. The eclipse from such a small, fast-moving shade would only last a few seconds.
Instead, our hosts are taking on the challenge of parking something much larger in front of the sun to block it. A planet might work, but none in our solar system are quite the correct size – plus it would be difficult to move a whole world, and the consequences for Earth might be dire. In fact, changing how much sunlight reaches the ground at all could be a problem…
The solution may be a series of small panels, blasted into space individually and flown in formation to block the sun. There would need to be a whole lot of them, but changing their orientation in flight could providesolar eclipses on demand – without necessarily destroying all life on Earth.
The total solar eclipse that passed across North America on 8 April drew millions out to the path of totality – the thin strip of land across which the moon’s silhouette blocked out the entire disc of the sun. Even more gawked at the partial eclipse visible across most of the continent. Here are five of New Scientist’s favourite images from 2024’s total eclipse.
The beginning of the solar eclipse
NASA/Aubrey Gemignani
On the right side of this image, which was taken in Kerrville, Texas, you can see the edge of the moon just beginning to encroach on the sun. Closer to the centre and left side of the sun are a pair of sunspots – dim areas where the surface of the sun is unusually cool.
Baily’s beads
NASA/Aubrey Gemignani
This picture, also taken in Kerrville, Texas, shows a phenomenon called Baily’s Beads. Just before and after complete totality, the topography of the moon allows small beams of sunlight to peek around its edges, creating bright spots on the edge of the moon’s silhouette.
The shadow of the moon
CIRA/NOAA
This image was taken by the GOES-East satellite, which observes Earth from space for weather monitoring and forecasting. The moon’s shadow swept across Mexico and the US during the eclipse, creating a pool of twilight-like darkness at its centre and partial eclipses at its edges.
Prominences
NASA/Joel Kowsky
During totality, pictured here from Indianapolis, Indiana, several prominences were visible on the edges of the sun. These are areas where the sun’s complex magnetic field shapes hot plasma into bright loops and flares that burst off the sun’s surface, and they are easiest to observe when the disc of the sun is blocked by the moon.
Visible corona
NASA/Keegan Barber
For scientists, the main importance of a total solar eclipse is that it provides a unique opportunity to view the sun’s diaphanous outer layer, the corona. When the disc of the sun is not blocked, it far outshines the corona, so an eclipse is the perfect time to study this mysterious sheet of plasma, shown here during totality in Dallas, Texas.
A total solar eclipse from August 2017 seen above Jefferson City, Missouri
(NASA/Rami Daud)
The following is an extract from our monthly Launchpad newsletter, in which resident space expert Leah Crane journeys through the solar system and beyond. You can sign up for Launchpad for free here.
It was 1919 when the moon did a perfectly natural thing – blocked our view of the sun – and changed our understanding of the universe forever. Astronomer Arthur Eddington was watching from the African island of Príncipe, observing the positions of stars and planets that became visible during the eerie daylight darkness. With most of the sun’s light dimmed, he was able to see how light from distant stars warped as it was deflected by our sun’s gravitational pull, an effect called gravitational lensing.
He confirmed his sightings with those of another expedition in Brazil, and these observations offered some of the first proof for Albert Einstein’s relatively new theory of general relativity. This description of how massive objects warp the fabric of space-time is now considered foundational, but at the time it was a revelation. It changed everything about how we think about gravity and the cosmos.
It also resulted in my favourite newspaper headline of all time, published in TheNew York Times later that year: “LIGHTS ALL ASKEW IN THE HEAVENS; Men of science more or less agog over results of eclipse observations. EINSTEIN THEORY TRIUMPHS Stars not where they seemed or were calculated to be, but nobody need worry.”
“Nobody need worry” might seem a bit over the top, but watching a total solar eclipse can indeed make you feel inexplicably nervous. I saw my first one in 2017. It was absolutely unforgettable. You might think that an eclipse is just like an overcast day with a cloud drifting in front of the sun – after all, what’s happening is simply the moon passing in front of the sun and casting a shadow on Earth – but it’s astonishingly different.
The first thing you’ll notice during a total eclipse is the shadow of the moon rushing over the ground towards you at speeds in excess of 2400 kilometres per hour. The area of shadow for April’s eclipse will be about 185 kilometres wide, but this can change slightly based on the exact orientations of the sun and moon. As the shadow grows near, the moon appears to take a bite out of the sun, and there’s a strange quality to the light, as if a fog has fallen.
Then, suddenly, it goes dark. This is totality. Temperatures drop by up to 10 degrees. The only light comes from the sun’s outermost layer, called its corona, which ripples beyond the silhouette of the moon. It becomes so dark that some stars are visible in the sky. Many animals, including birds and insects, understandably seem to think that it’s nighttime, so the otherworldly twilight goes quiet except for the chirping of nocturnal insects that have awoken. I can’t say how you will feel, but for me it was a mix of awe and a strange, primal terror – the sun disappeared, and while my mind knew why, my body panicked at its loss.
Solar Eclipse 2024
On 8 April a total solar eclipse will pass over Mexico, the US and Canada. Our special series is covering everything you need to know, from how and when to see it to some of the weirdest eclipse experiences in history.
This seems to be a fairly common reaction, and not only in humans. Researchers studying animals during past total eclipses have found that while some simply went about their evening routines early, many of them showed signs of anxiety, running aimlessly or huddling together during totality.
Then, after just a few minutes, totality recedes just as quickly as it arrived. The shadow rushes away, the sun comes back out, and the birds and insects resume their chirping. The astronomers look up from their solar telescopes, groggy but excited at the treasure trove of data they’ve gathered.
Over the thousands of years humans have been observing solar eclipses, we’ve learned some pretty fascinating things. With the disc of the sun covered by the moon, its faint corona becomes visible, making an eclipse the perfect time to study the outer reaches of the sun. For example, scientists first discovered helium during a total solar eclipse. Eclipses are also the best times to observe the plumes of radiation and matter emanating from the surface of the sun through the corona. The corona itself is quite strange, and there’s plenty left to unravel about how it works – despite being far from the sun’s central fusion, the corona is millions of degrees hotter than the sun’s surface, and we still don’t know why.
Even if you’re not studying the sun’s mysterious layers, seeing a total solar eclipse is completely worth it. Those newspaper editors had it right more than a century ago: it’ll leave you more or less agog.
A total solar eclipse is a great opportunity to learn more about the sun
ESA/Royal Observatory of Belgium
A total solar eclipse occurs somewhere on Earth about every 18 months, and that has been the case for all of human history. Naturally, people have been studying these dramatic events for just as long, with the first known written record of an eclipse dating back more than 3000 years. In all that time, we have learned an astonishing amount from total eclipses about the sun, Earth and even the fundamental laws of physics.
For much of history, totality – the period of time in which the moon covers the entire disc of the sun – has been the only time that humans could see the sun’s faint outermost layer. This wispy shroud of plasma, called the corona, has been central to many of the scientific advances that have come from the study of eclipses.
Solar Eclipse 2024
On 8 April a total solar eclipse will pass over Mexico, the US and Canada. Our special series is covering everything you need to know, from how and when to see it to some of the weirdest eclipse experiences in history.
The corona is home to many of the sun’s most fascinating phenomena, including coronal mass ejections (CMEs), which occur when the sun’s churning magnetic field blasts strands and blobs of material out into space. CMEs that hit Earth can damage satellites and the electrical grid, and they can be extraordinarily dangerous to astronauts out in space, beyond the protection of Earth’s atmosphere.
“The magnetic activity of the sun changes over time and changes across the surface of the star,” says Meredith MacGregor at Johns Hopkins University in Maryland. So far, we don’t have a good way to predict this activity. But we might be able to begin doing so by studying the corona.
A total solar eclipse isn’t the only way to look at the sun’s outermost layers – there is also an instrument called a coronagraph, which uses a shade to block out the disc of the sun in a sort of artificial eclipse. These instruments are important not only for studying our own star, but also for studying other, more distant stars and searching for any planets orbiting them that would otherwise be hidden in the glare of starlight. “The inspiration to use coronagraphs to block out the light of other stars so we can look for their exoplanets comes from natural eclipses,” says MacGregor.
The same dimness that makes the corona difficult to observe outside of totality also makes it an excellent target for spectroscopy. Spectroscopy works by breaking down light into its constituent wavelengths. This allows researchers to determine what elements are present in a material by the unique pattern of wavelengths each element emits or absorbs. Helium was discovered using spectroscopy during an eclipse in 1868, which was the first time any element was discovered by studying the skies.
Soon afterwards, astronomers found what appeared to be another new element in the corona, which they termed coronium, but it turned out to simply be iron heated up to extraordinary temperatures of millions of degrees. Even though it wasn’t a new element, this was a baffling find – the surface of the sun is only about 5600°C, so how could the outermost layer be so sweltering?
“Imagine you’re at a campfire, and you start walking away from the campfire. And it should be getting colder, but it gets far hotter,” says Frederic Bertley at the Center of Science and Industry in Ohio. “That’s what’s going on in the corona, and nobody knows why that is.”
Solar eclipses even provided some of the first proof of Albert Einstein’s general theory of relativity, which governs how gravity behaves on large scales. One of the major predictions of general relativity is that massive objects should bend the trajectory of light as it passes by them. Einstein first presented his theory in 1915, and evidence for its veracity came in 1919, when astronomer Arthur Eddington observed starlight bending around the sun during a solar eclipse.
When a total solar eclipse passes over Central and North America this month, astronomers will continue their long tradition of taking advantage of totality to make precise observations of the sun and how it affects the space around it. The sun still has many secrets to unravel, and an eclipse is one of the best times to study them.
NASA’s WB-57 research jets will be used to study the eclipse
Amir Caspi
Across North America, solar scientists will be studying April’s total solar eclipse to view the strangest part of the sun: the corona.
Seen fleetingly as a bright halo that appears only during totality, it is a million times dimmer than the rest of the sun in visible light. The corona is also a million degrees hotter than the sun’s surface, or photosphere, which reaches only about 6000°C, and it extends millions of kilometres into the solar system.
The corona is where the sun’s magnetic fields act on charged particles to form complex shapes, known as streamers, loops and plumes, among other names. Understanding the corona will help us predict the solar wind, the stream of charged particles hurled from the sun into space. This is what causes aurorae, but it is also a potential threat to astronauts, satellites and electricity grids.
Expectations are sky high for the total solar eclipse on 8 April because totality – when the sun is entirely covered – will last up to 4 minutes and 27 seconds – the longest such period on land for over a decade. Here are a few of the experiments that will be taking place.
The solar wind sherpas
Shadia Habbal, a solar researcher at the University of Hawaiʻi Institute for Astronomy, has been chasing solar eclipses for almost 30 years, using special filters and cameras to measure the temperatures of the particles from the innermost part of the corona.
Habbal’s group, now known as the Solar Wind Sherpas, has travelled to places as far afield as the Marshall Islands, Kenya, Mongolia, the Norwegian archipelago of Svalbard, Antarctica and Libya. At each eclipse, some of which last just a few seconds, Habbal and her team image the corona using their filters. Studying the different wavelengths of light emitted by charged iron particles in the corona lets them tease out temperatures.
Most of the time, solar physicists studying the corona rely on coronagraphs from space-based observatories, which use a disc on a telescope to block the sun. But these devices cover up the innermost part of the corona, the source of towers of plasma called prominences and eruptions called coronal mass ejections.
“Observations during totality are critical,” says Habbal. There is no other way to see the part of the sun’s atmosphere that extends from its surface out to at least 5 solar radii in a continuous manner. “That’s fundamental to understanding how the solar atmosphere starts at the sun and then extends into interplanetary space,” she says. Only then can accurate computer models be devised that simulate the corona and help in the prediction of space weather.
In the past couple of years, Habbal’s group has made an astonishing discovery. Right now, the sun is heading towards solar maximum in 2025, the most active point in its 11-year cycle, when the solar wind intensifies. Since the corona looks much larger during total solar eclipses at solar maximum, it was thought that the solar cycle and the temperature of the corona are inextricably linked. But it might not be so simple.
In 2021, Habbal and her colleagues published research from observations taken during 14 total solar eclipses that suggests the corona’s temperature isn’t dependent on the solar cycle. The lines of the sun’s magnetic field can be open, travelling outwards with the solar wind, or closed, which are hotter and form loops. “We found open field lines everywhere regardless of the cycle,” says Habbal. This means the corona has a roughly constant temperature.
The high fliers
Bad weather has prevented observations since 2019. “We had rain in Chile in 2020, clouds at sea in Antarctica in 2021 and there was no eclipse in 2022,” says Habbal. It was during the expedition to Antarctica that team member Benedikt Justen suggested that next time they could fly a kite equipped with a spectrometer, which separates light into its component wavelengths.
The NASA-funded kite, which has a 6.5-metre wingspan, was successfully tested in Western Australia during a total solar eclipse in April 2023. It was launched on a kilometre-long tether attached to a vehicle. “It was pretty miraculous,” says Habbal. Bad weather meant that the team flew it for the first time just 45 minutes before totality. “It was thrilling.”
This box-shaped kite will fly a NASA-funded scientific instrument to study the total solar eclipse
Klemens Brumann and Benedikt Justen
If the technology works well at the upcoming eclipse, the kite will be deployed more in future, probably with cameras added. “It’s much easier and cheaper than using balloons,” says Habbal. But if it doesn’t work, there is always a backup.
During the total eclipse, two WB-57 planes will follow each other at 740 kilometres per hour, about a quarter of the speed of the moon’s shadow, just south-west of the maximum point of the eclipse. At that speed, totality increases from the 4 minutes 27 seconds for those viewing it from the ground to over 6 minutes. “The WB-57 is perfect for this because in its nose cone is a camera and telescope system that can rotate to point at anything… no matter which way the aircraft is flying,” says Amir Caspi at the Southwest Research Institute in Boulder, Colorado, who is in charge of an experiment in the second WB-57 to study the corona in a different way.
Using a stabilised platform, Caspi and his team will capture images of the eclipse using both a visible-light camera and a higher-resolution mid-infrared camera developed by NASA. The latter will capture seven different wavelengths of light and help determine which structures in the corona emit their own light and which merely scatter light from the sun’s surface. “We need to be above as much of the atmosphere as we can get to make those observations,” says Caspi. Infrared light is absorbed by Earth’s atmosphere and is hard to observe from ground level.
The live streamers
Caspi is also part of the Citizen Continental-America Telescopic Eclipse (CATE) project, an attempt to make a continuous 60-minute high-resolution movie using 35 teams of citizen scientists in the path of totality, from Texas to Maine, each with the same cameras, telescopes and training so they can make exactly the same kinds of observations. “The teams will be spaced out so that every station is overlapped by its neighbours,” says Caspi. “If one station doesn’t get data, because of clouds or broken equipment, it’s OK.”
He is hopeful the equipment will work, since it was successfully tested last year in Western Australia. “That was the first eclipse I’ve seen,” says Caspi, who only got to see a few brief seconds because he was busy live streaming it on YouTube. “Our equipment couldn’t get online, so I spent the whole time holding my phone in front of my face.”
Solar Eclipse 2024
On 8 April a total solar eclipse will pass over Mexico, the US and Canada. Our special series is covering everything you need to know, from how and when to see it to some of the weirdest eclipse experiences in history.
The movie will hopefully allow scientists to study the corona’s complexities, notably its shape and how it changes over a short time. It builds on a CATE project from 2017, which used 68 cameras throughout the path. This time, it will use more sophisticated cameras that are sensitive to different types of polarised light.
“Most of the light that you see during totality is actually light from the surface of the sun that goes up into the corona to scatter off electrons,” says Caspi. This is the K corona, the bright inner part, which overwhelms the light coming only from the corona itself. As the light scatters, it becomes angled, a property called polarisation. “If you can measure the angle of polarisation, then that gives you a 3D structure of the corona, its density and how that changes over time,” he says.
Time is in short supply during a total solar eclipse, so a continuous hour-long video makes it possible to capture processes that take seconds or minutes, like a solar flare or coronal mass ejection, as well as other details. “The corona is permeated by a complicated magnetic field,” says Caspi. “During totality, we don’t see the magnetic field, but instead the hot plasma trapped along it – just like being able to see iron filings around a magnetic field around a magnet.”
THIS captivating shot, showing the sun and full moon perfectly aligned over the Valley of the Gods in Utah last October, amps up anticipation for next month’s total solar eclipse in North America.
A collaboration between photographers Andrew McCarthy and Daniel Stein, the image shows an annular solar eclipse, where an outer “ring of fire” forms because the moon is too far from Earth to fully cover the sun. The shot is the result of thousands of images pieced together digitally, pairing Stein’s landscape photography skills with McCarthy’s experience at capturing images of the sun.
After months of planning, the pair got their crucial shots by positioning cameras and telescopes at a carefully selected desert location, taking into account aspects like weather patterns, eclipse duration and landscape features.
The image was released on social media on 8 March, exactly one month before a total solar eclipse will pass over North America, during which the moon will entirely cover the sun. It will shroud many parts of the continent – from Canada to the US and Mexico – in darkness, or totality. The path of totality is due to be much wider than the last such eclipse that occurred in the region: almost 200 kilometres will be covered, compared with about 115 kilometres in 2017.
“It’s easy to take the sun for granted… but when the [sun and moon] combine during an eclipse, it is breathtaking. We feel bringing in the landscape element then adds a sense of grounding to the image, allowing the viewer to really connect with the piece,” says Stein.
We are still trying to understand how animals respond to a solar eclipse
Ş. Uğur OKÇu/1001slide/iStockphoto/Getty Images
A total solar eclipse is impossible not to notice – the disc of the sun is completely covered by the moon, its shadow rushes across the surface of the earth, the temperature drops precipitously. Even animals seem to notice, and researchers around the world have studied how they react.
Researchers have observed all sorts of animals during solar eclipses, from wild hippopotamuses to pet dogs. Some of the most thorough studies, though, have been performed in zoos around the world.
Adam Hartstone-Rose at North Carolina State University and his colleagues performed one of the biggest such studies during the eclipse that crossed the US in 2017. “To be entirely honest, I didn’t think we were going to see anything interesting. Animals see clouds go overhead all of the time, occasionally it’s overcast – I didn’t think animals were going to care at all about this,” says Hartstone-Rose. “Astonishingly, three-quarters of the species that we watched had some sort of reaction.”
Most of those animals seemed to think it was nighttime during totality, the period in which the sun was completely hidden behind the moon. This might not come as a surprise to those who have witnessed a solar eclipse anywhere outdoors, as it has been known for centuries that birds and insects tend to quiet down and seek their nests.
“The gorillas usually hang out on the yard all day and then they go inside at night, so during totality the whole group of gorillas sort of marched over to the door and were perplexed why no one was letting them in,” says Hartstone-Rose. Similarly, he observed birds going to their roosts to bed down. Once totality ended, the gorillas and birds went back to their normal daytime activities. Past studies have also seen spiders taking down their webs during totality and bats briefly emerging from their daytime resting spots.
The other reaction that the researchers spotted in many of the animals was anxiety. “We have a lot of experience trying to assess anxiety in animals, especially in zoo animals, because we’re always trying to mitigate that,” says Hartstone-Rose. “So we’re very cognisant of behaviours that might indicate anxiety.”
These reactions can include pacing, huddling together and increased vocalisation. “Giraffes only run when they’re basically running for their lives, but during the eclipse some of the giraffes started running around like the sky was falling down,” says Hartstone-Rose. “A few animals had reactions like that.” Baboons, for example, were seen to cluster into groups and run around together.
Solar Eclipse 2024
On 8 April a total solar eclipse will pass over Mexico, the US and Canada. Our special series is covering everything you need to know, from how and when to see it to some of the weirdest eclipse experiences in history.
A few animals performed completely novel behaviours – some Galapagos tortoises began mating during the eclipse, and all of them gazed up at the sky after totality had passed. Past studies of hippopotamuses have found that they, too, remained agitated even after the peak of an eclipse.
However, it is difficult to tell which animal behaviours are caused by the eclipse itself and which are a reaction to the crowds of people an eclipse draws – particularly in zoos, where animals and people are in close contact. For the same reason, it is difficult to reach conclusions about changes in pet behaviour during an eclipse.
Hartstone-Rose and his colleagues will be conducting another zoo study during the total solar eclipse on 8 April, observing some of the same species as last time to see if their behaviour matches, as well as collecting data on new species. They are also running a participatory science project through which anyone can report their observations of animals during the eclipse. By searching for patterns in animals’ behaviour during unusual events like eclipses, we may be able to understand their thought processes more generally.
Pink streaks called prominences appear during a total eclipse
Alan Dyer/Stocktrek Images/Getty Images
There is no experience in life like witnessing a total eclipse of the sun. For a few moments, the sky goes dark, the air gets cold and the stars come out in the middle of the day. Some people will go through life never seeing one, but eclipse chasers like me can’t get enough.
The thrill of anticipating the next total eclipse comes from the fact that each one is totally unique. They can last anywhere from a single second to over 7 minutes, and they happen over varying types of geography and geology, usually over the sea.
The total solar eclipse on 8 April will only be visible to those in a path about 185 kilometres wide, where the sun will be completely eclipsed for up to 4 minutes and 26 seconds. Just before, during and after these magical minutes, those in the path of totality should look out for a range of phenomena. Clear skies allowing, here’s what to expect from a total solar eclipse:
Sunspots being covered by the moon
This is one sight that everyone across North America has a chance of seeing. At the moment, the sun is approaching the most active part of its cycle, called solar maximum, which lasts between 11 and 17 years. This means magnetic activity is as high as it gets, causing visible sunspots on the sun’s surface. If these dark, cool, magnetically complex regions are large enough, they can be seen at any time through eclipse glasses. Watching them gradually being covered by the moon during an eclipse is an interesting sight, even for those outside the path of totality.
Shadow bands on the ground
Between a couple of minutes and about 30 seconds before the sun becomes totally eclipsed, the from its surface, called the photosphere, comes from only a slim crescent. When this happens, it is sometimes possible to see wavy lines moving swiftly across light-coloured surfaces. “A [bed] sheet or other white-ish surface placed on the ground may show shadow bands,” says Frank Maloney at Villanova University in Pennsylvania. “These are due to that sliver of photospheric light that travels through our atmosphere and essentially ‘twinkles’ in roughly parallel bands.” Whether they become visible depends on the amount of turbulence in Earth’s atmosphere.
Solar Eclipse 2024
On 8 April a total solar eclipse will pass over Mexico, the US and Canada. Our special series is covering everything you need to know, from how and when to see it to some of the weirdest eclipse experiences in history.
Darkness, Baily’s beads and the first diamond ring
Just before totality, the final 0.1 per cent of the sun disappears and the light levels crash. Now come the beads. “In the few seconds before and after totality, one may see Baily’s beads as the last bits of the sun can be seen shining through the moon’s irregular surface,” says Maloney. The final bead shines like a jewel for a second, just as the sun’s corona appears, creating a brief “diamond ring” effect around the moon. It is safe to look at the diamond ring without eclipse glasses, but most observers miss it because they still have them on.
Solar corona
Here it comes – one of the most glorious sights in all of nature. “During totality, when the sun’s photosphere is eclipsed, the other parts of the sun’s atmosphere, the white corona and the pink-purple chromosphere, become visible,” says Maloney. Darkness has arrived and you can safely remove your eclipse glasses and look with your naked eyes at the corona, which is expected to be spiky and star-like because the sun is nearing its most active phase of its cycle. You will see wispy extended tendrils in the corona, if you have binoculars.
Pinkish-red chromosphere and prominences
At the onset and just before the end of totality, you will see the chromosphere, the lower region of the sun’s atmosphere, as a pinkish band that disappears mid-eclipse and remerges on the other side as the moon moves across the sun. You are also likely to see prominences, pinkish-red towers, or loops of plasma and magnetic field structures protruding from the corona visible around the moon.
The second diamond ring
The most impactful diamond ring effect comes at the end of totality. Tiny beads of sunlight appear between the moon’s mountains and valleys before merging into one bright diamond ring, the appearance of which marks the end of totality. It is safe to look at for a few seconds, but as daylight returns it is necessary to put eclipse glasses back on if you want to continue looking at the partial phases.
As totality ends, shadow bands can sometimes be seen again. You will have at least another hour to watch the sun, and any sunspots, slowly being uncovered – with your eclipse glasses back on, of course.
Viewing a total solar eclipse is an experience that can stay with you for life, but, without the proper precautions, that could be for all the wrong reasons. Looking directly towards the sun is dangerous, so read on for how to view an eclipse safely and what you need to organise in advance.
On 8 April 2024, a total solar eclipse will be visible to over 42 million people across North America. The path of totality is only about 185 kilometres wide, touching parts of Mexico, 13 US states and Canada. Most people in North America will experience this event not as a total solar eclipse but as a partial.
“For those outside the path of totality, the moon will never fully cover the sun,” says Jeff Todd at Prevent Blindness, an eyecare advocacy group based in Chicago. Regardless of your vantage point, eye protection is essential.
“To avoid damaging your eyes, you need to wear eclipse glasses for the entire duration of the eclipse,” says Todd. Otherwise, you risk burning your retinas. Nicknamed “eclipse blindness”, this can happen without you feeling any pain and it can be permanent. It can take days after viewing the solar eclipse to realise anything is wrong. Sunglasses don’t provide adequate protection. However, it is perfectly safe to hold eclipse glasses over prescription glasses.
How to view the eclipse safely
For those who travel into the path of totality, the prize is a naked-eye view of the sun’s corona. However, it is only visible during the brief few minutes of totality. At all other times, the partial phases will be visible, which must be observed through eclipse glasses. Todd says that those inside the path of totality also need to wear eclipse glasses at all times except during totality, the short period when the sun is totally eclipsed by the moon and it gets dark. “Only then can you remove your eclipse glasses,” he said.
It is important that people inside the path of totality use their naked eyes to view the totally eclipsed sun. “You have to look without a protective filter, otherwise you will see nothing,” says Ralph Chou at the University of Waterloo, Canada.
Solar Eclipse 2024
On 8 April a total solar eclipse will pass over Mexico, the US and Canada. Our special series is covering everything you need to know, from how and when to see it to some of the weirdest eclipse experiences in history.
Just before the end of totality, light from the sun’s photosphere will stream between the mountains and valleys on the moon. Called Baily’s beads, they will appear for a few seconds and eventually become a “diamond ring” that flashes, revealing enough of the sun’s photosphere for daylight to return. “They provide plenty of warning that it is time to resume looking at the partial eclipse with a protective filter,” said Chou.
Which eclipse glasses should I get?
It is crucial to wear eclipse glasses that meet the ISO 12312-2 international standard, which applies to products intended to be used for direct viewing of the sun. “Look for ISO standard labelling and purchase your glasses from a trusted source,” says Todd. “Get your glasses early to ensure that you have them in time for the eclipse.” Before making a purchase, check that the company or brand is on the American Astronomical Society’s vetted list of suppliers and resellers.
Eclipse glasses must not be used with binoculars and telescopes. If you want to use these devices to view a solar eclipse, they must have a solar filter over their objective lens – the lens at the other end to the one you look through. You should never put solar filters or eclipse glasses between the eye and the eyepiece of a telescope or the eyecups of binoculars.
Other safe ways of viewing the eclipse include a pinhole projector – a simple device that projects the sun’s image through a small hole onto a piece of paper or cardboard. An even easier way is to make use of the well-defined small holes in a colander or spaghetti spoon, which will project small crescent suns onto any surface.
Eclipses happen due to an amazing cosmic coincidence that means the moon appears as large as the sun
Chancey Bush/The Albuquerque Journal via AP
People travel thousands of miles to see eclipses. There is nothing quite like the darkness that descends and the excitement that ripples through the crowd. A total solar eclipse will soon grace the skies across parts of Central and North America, with some locations outside the path of totality able to see a partial eclipse of the sun. So now is as good a time as any to ask: what exactly is a solar eclipse?
When one celestial body is obscured from view by another body that moves in between, astronomers refer to the event as an “occultation”. Technically, total solar eclipses are occultations of the sun by the moon.
A total solar eclipse happens when the moon and sun line up perfectly, such that the moon moves in front of the sun and blocks out nearly all of its light. When viewed from the path of totality – the stretch of Earth that will see the total eclipse – the sun all but disappears. This part of an eclipse can last for up to 7.5 minutes. The 8 April eclipse will last 4 minutes and 27 seconds.
What causes a solar eclipse?
There are many kinds of solar eclipse, but each happens when the moon passes in front of the sun, blocking out some or all of its light as viewed from a specific part of the planet. By sheer cosmic coincidence, the moon and the sun appear the same size in the sky because the moon is about 400 times as small as the sun, but the sun is about 400 times as far away. When the two line up perfectly during the new moon lunar phase – when the moon sits between Earth and the sun – the moon can block out the entirety of the sun’s light. This is a total solar eclipse.
During an eclipse of the sun, the moon casts two shadows. The middle part of the shadow, where no light reaches, is called the umbra. The outer partial shadow is known as the penumbra; here, only light that has come from part of the sun’s disc can reach. During a total eclipse, the path of totality is the stretch of land within the umbra. On 8 April, this path will be 185 kilometres wide, stretching across North America from Mexico, through the US and Canada. But the path of totality can be as narrow as 150 kilometres. The penumbra covers a much greater area, and in those places viewers will be able to see a partial solar eclipse.
NASA Goddard Space Flight Center Conceptual Image Lab
What are the different kinds of solar eclipse?
A partial eclipse happens when the moon just blocks out a portion of the sun’s light. This occurs when viewers are within the penumbra. Before and after totality, viewers can see the moon slowly encroaching on the sun in a partial eclipse. But there are also times when only a partial eclipse is visible from anywhere on Earth because the moon’s central shadow misses our planet completely.
An annular solar eclipse happens when the moon’s elliptical orbit puts it further from Earth than usual, so it obscures most of the sun’s light but leaves what is known as a ring of fire. Hybrid eclipses occur when a total eclipse is visible from some parts of the world, but an annular eclipse is visible from others. Total, hybrid and annular eclipses are all types of “central” eclipse, meaning the umbral shadow is cast somewhere on Earth.
Solar Eclipse 2024
On 8 April a total solar eclipse will pass over Mexico, the US and Canada. Our special series is covering everything you need to know, from how and when to see it to some of the weirdest eclipse experiences in history.
How often do solar eclipses occur?
Each year, between two and five solar eclipses are visible somewhere around the world. Total solar eclipses happen, on average, every 18 months. But for a given spot on the planet, total eclipses of the sun are only seen every 400 years or so, since the portion of Earth from which each total eclipse is visible is so small.
What is a lunar eclipse?
A lunar eclipse happens when the moon moves through the shadow Earth casts into space. These events always occur during the moon’s full phase, when the moon is on the opposite side of the planet from the sun. But they don’t happen every full moon, because our moon’s orbit is tilted around Earth compared to Earth’s orbit around the sun.
Do eclipses always come in pairs?
Since eclipses are caused when Earth and the sun and moon line up in a row – in what is called syzygy – a solar eclipse is always accompanied by a lunar eclipse, either two weeks before or after. This year there will be a lunar eclipse on 24 March, two weeks before the 8 April solar eclipse. But it will be a penumbral lunar eclipse, meaning only Earth’s outer shadow will obscure the moon.
