A total eclipse occurs somewhere in the world about once every 18 months on average, and that has been the case for all of human history. For millennia, humans have been documenting their views as the moon moved between Earth and the sun, blocking out the sun’s light and revealing its swirling outer layers.

The earliest confirmed written record of a solar eclipse comes from the 13th century BC, when scribes in China wrote that the sun had been “eaten”. Scientific and religious texts continued to document eclipses up until the present day, and researchers now use these texts to study both how eclipses have changed in the intervening centuries and how human views of them have evolved throughout time. This particular petroglyph, carved into stone by the early Pueblo people in New Mexico, is thought to represent a total solar eclipse that occurred on 11 July 1097. The swirls around its perimeter bear a resemblance to the corona of the sun, which is only visible when the moon hides the rest of the solar disc.

More recent art depicts religious and scientific figures observing eclipses directly. This watercolour from the late 17th century shows a group of French missionaries observing a solar eclipse with King Narai of Siam and his court in April 1688. They can be seen using the projection method to avoid looking directly at the sun: the light passes through a telescope and projects the shape of the eclipse on a screen beneath it. This technique is still commonly used today, with pinhole cameras or even just the gaps between shadows cast by leaves on the ground.

Scientific sketches of eclipses proliferated as science became more of a formal, professionalised pursuit. This drawing, by astronomer José Joaquín de Ferrer, depicts an eclipse that occurred over New York on 16 June 1806. Watching this event led de Ferrer to give the outermost layer of the sun, the corona, its name. He was among the first people reported to have hypothesised that the corona must be part of the sun, not the moon, because of its incredible size – it can stretch to as much as 20 times the width of the main disc of the sun, as he sketched here.

The first photograph of a total solar eclipse with enough detail on the corona to be scientifically useful was taken on 28 July 1851 by Julius Berkowski at the Royal Observatory in Königsberg, Prussia. With help from the astronomers at the observatory, he attached a small telescope to a device called a heliometer, a specialised instrument for measuring the sun. This daguerreotype was an 84-second exposure taken through the telescope. Not only is the corona visible, but several eruptions can be seen blasting from the sides of the sun over the edge of the moon.

After Berkowski’s image, the ability to take photographs of eclipses became more widespread around the world. These images were taken by William and Frederick Langenheim on 26 May 1854 in Philadelphia, Pennsylvania. Without access to the scientific tools Berkowski used to magnify the light from the eclipse, they were forced to use small cameras to create these miniature daguerreotypes, the largest of which is just 7.2 centimetres tall and the smallest less than half that size.

The total solar eclipse that swept over parts of Africa and South America on 29 May 1919 proved to be one of the most important eclipses ever observed. This image comes from the expedition that astronomer Arthur Eddington made to the African island of Principe. He and his team photographed several stars located close to the sun to compare their apparent positions in the sky before and then during the eclipse. In this image, the stars are marked with horizontal lines. The comparison proved that the gravity of the sun bent the light coming from those stars, providing some of the first evidence for Albert Einstein’s theory of general relativity and creating a new understanding of the workings of the universe.

Eclipses became popular photographic targets for scientists and non-scientific photographers alike. This image, taken by Frederick Goetz on 24 January 1925, shows an effect called the diamond ring, or Baily’s beads. This effect occurs just at the beginning and end of totality, when the edge of the moon is nearly, but not quite, covering the entire disc of the sun. Ridges and craters on the moon’s surface let through only a few rays of sunlight, creating the glare that earned Goetz’s inscription of “Signs and Wonders”.

Modern images of solar eclipses, such as this one taken in California on 11 July 1991, display the corona in much more detail than has ever been achievable before. Past observations revealed an astonishing mystery: the corona is about 300 times hotter than the sun’s surface. Eclipses provide prime opportunities to try to figure out how and why it gets so hot, plus research how we might be able to predict solar activity someday to mitigate its potential effects on satellites, astronauts and even electrical grids on Earth.

The sun itself is, of course, not the only thing that researchers study during eclipses. As seen in this image taken in Chile on 2 July 2019, during a total solar eclipse the sky darkens almost completely. Temperatures drop precipitously. Birdsong ceases almost entirely. Through studying how animals react, researchers try to decipher what they may be feeling and thinking, and how they perceive the unexpected darkness.

When viewing an eclipse from the ground, it can be hard to imagine the scale of it. These images of an 8 April 2024 eclipse, taken by NASA’s Deep Space Climate Observatory (DSCOVR) satellite, show that handily. The dark spot moving across the planet in these pictures is the shadow of the moon. People standing within that spot witness totality, and those along the edges see only partial eclipses.

Our ability to image and understand these phenomena has come a long way since petroglyphs in stone walls – imagine what we’ll be able to see in another few thousand years.

During the total solar eclipse on 12 August, scientists from around the world will have their eyes – and scientific instruments – on the sun. But even if you aren’t a scientist, you can help in their investigations, both during the eclipse and year-round.

A total solar eclipse occurs when the sun and moon line up just right so that the moon blocks out the entire disc of the sun from the perspective of Earth. It is a huge cosmic coincidence that both the sun and the moon happen to be just the right size and at the right distance to give us such a spectacle, and a scientifically useful one at that.

On 12 August, a total eclipse will be visible over parts of Europe and the Arctic and Atlantic oceans, with a partial eclipse covering much of Europe, Canada, north-west Africa and parts of the US. An eclipse like this one is visible from somewhere on Earth just once every 18 months approximately, so during each eclipse, scientists rush out to gather as much data as they can. Here are some ways that you can help out:

1. Record shadow bands from the path of totality: In the moments before and after a total solar eclipse, strange phenomena called shadow bands billow across the ground. These bands are caused by the combination of Earth’s atmosphere and the hidden disc of the sun – it is similar to the effect that causes more distant stars to twinkle. If you are in the path of totality, all you have to do to see them is set out a white sheet or piece of cardboard perpendicular to the direction of the sun. To , which aims to quantify how shadow bands differ based on altitude and distance from the centre of totality, just set up a camera to film the sheet.

2. Photograph the sun with your smartphone: The sun is very nearly spherical, but it isn’t perfect. One of the best ways to measure its shape with precision is to have lots of pictures taken from lots of different locations – that’s what does. It’s a smartphone app that you can set up and leave running as you enjoy watching the eclipse, and it will take carefully timed pictures to capture a phenomenon called Baily’s Beads, or the diamond ring effect. When the very last of the sun is about to be covered by the moon, the lunar landscape lets through tiny points of light, which shine along its edge. The same happens when the other side of the moon is just about to let the sun shine past it again, and these points of light are Baily’s Beads. When lots of photos of the beads, all precisely geolocated, are combined with a map of the lunar topography, that can give us an extraordinarily precise measurement of how far the disc of the sun is from a perfect circle.

3. Measure the darkening of the sky during the eclipse: Even if you are only going to see a partial eclipse, you can still help with scientific research. The Gaia4Sustainability project requires a little bit more equipment and set-up time, but once you have it sorted, you can leave it running all year round and keep collecting useful data. It consists of a small device with a bunch of sensors on it to measure the brightness of the sky and other meteorological factors, and the overarching goal of the programme is to measure light pollution so we can better understand its effects. But during the eclipse, the same sensors can be used to , and the more different spots the team has data from, the more they will be able to learn about atmospheric dynamics during eclipses.

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4. Hunt for sun-grazing comets: As is the case for pretty much all astronomical events, a huge portion of the world won’t be able to see August’s total eclipse at all. Not to worry! There are still ways to get involved in solar science. In the , you can download satellite pictures of the sun and look for moving objects on its outskirts. Some of the objects will be comets skimming past the sun, and once researchers know those comets are there, they can do more detailed research. A huge proportion of the known comets were discovered through Sungrazer. All it takes is a computer, an internet connection and some spare time.

5. Join a DEB observation team for next year: If you want to do something a bit more involved, the might be more up your street. It’s an scheme where teams receive training and some relatively basic equipment to observe eclipses across the path of totality, building up a huge repository of data that can then be used to study the evolution of the corona, the outermost layer of the sun’s atmosphere. Because of the training required, it is too late to join or create a DEB team for this year, but if you are going to be able to spot the 2027 eclipse that will sweep over northern Africa, you can sign up ahead of time.

Even during the eclipse, you shouldn’t look directly at the sun without a solar filter or eclipse glasses to protect your eyes.

One of NASA’s premier space telescopes is falling, and an audacious mission to rescue it has just begun. The Neil Gehrels Swift Observatory is months from dropping back to Earth, but if the rescue works, it could continue watching the sky for years to come.

All satellites’ orbits eventually decay, and Swift is no exception. The outer edges of Earth’s atmosphere have been dragging it down since it launched in 2004: its initial orbit was at an altitude of about 600 kilometres from the ground, and now it’s only about 375 kilometres up. Its descent in recent years was faster than expected because of powerful solar flares depositing energy into the atmosphere, puffing it outwards and increasing drag on satellites.

So if NASA wanted to keep Swift operating, the agency had few options. The one that won out was a proposal by Katalyst Space Technologies, a small start-up based in Arizona, to give the orbiting observatory a boost.

The plan rests on a satellite called LINK, designed to grab Swift with a trio of robotic arms and pull it upward. At less than 2 metres tall, its main body is only about one-third the size of Swift, but it is flanked by immense sheets of solar panels to power its thrusters and grappling arms.

LINK launched atop a Northrop Grumman Pegasus XL rocket on the morning of 3 July, in what is intended to be the final launch for Pegasus XL before it is retired. The spacecraft will now go through a few weeks of testing in space before it grabs Swift and slowly pushes upwards for about two months, letting go when it reaches its original 600-kilometre altitude. If all goes well, this manoeuvre will keep Swift operating for as much as a decade longer.

Swift was originally built to study gamma-ray bursts, which are the brightest and most powerful explosions in the universe. Over the years, it has detected about 1800 of these blasts, and has also made crucial discoveries about other cosmic objects, ranging from comets and planets to supernovae and black holes.

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Boosting it will allow it to continue observing, but if it works, it will also be an important demonstration that it is possible to save a space telescope. “Swift wasn’t designed to be serviced,” said Ghonhee Lee, CEO of Katalyst, in a . “By demonstrating we can quickly and cost-effectively extend its lifetime, we’re creating a blueprint for servicing spacecraft that were never designed for on-orbit maintenance.” This could be a cost-effective way to extend the lifetimes of other satellites as well, in particular the Hubble Space Telescope, which is predicted to fall in the 2030s if it doesn’t get a boost.

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The Vera C. Rubin Observatory in Chile is finally beginning its mammoth survey of the universe. After a year of testing and calibration, it is starting the Legacy Survey of Space and Time, which is poised to become the most detailed record of the universe ever captured.

“Today, we begin filming the greatest cosmic movie ever made,” said Brian Stone at the US National Science Foundation in a .

For the next decade, Rubin will collect about 10 terabytes of data every night in the form of hundreds of high-resolution images of the southern sky. Each image will cover an area about 40 times the size of the full moon, and the completed survey will include nearly the entirety of the sky that is visible from the southern hemisphere.

This treasure trove of data will serve several purposes. The first, which has already begun, is to alert researchers to anything changing in the night sky, such as the appearance of supernovae or the motion of asteroids and comets.

“Millions of alerts in just the last couple of months show that Rubin is up and running as a discovery machine,” said at Stanford University in California, who is part of the Rubin team. “Now we’re putting it all together.”

These alerts have already led to the discovery of more than 11,000 new asteroids, and they are expected to result in the most complete inventory of solar system objects ever created.

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In addition to canvassing the solar system, Rubin will provide information about more distant objects, building a detailed map of the Milky Way galaxy and peering deeper into the universe.

An early-release image (above) shows a sea of stars, interstellar gas and even distant galaxies. Such deep, detailed images taken again and again over 10 years will enable researchers to study rare cosmic events and even gain insight into dark matter, dark energy and the expansion of the universe.

On 12 August, a total solar eclipse will sweep across parts of Europe and the Atlantic ocean as the moon passes between Earth and the sun, blocking out sunlight. Parts of the US and Africa, along with the entire UK and much of Europe and Canada, will see a partial solar eclipse.

Where can I see the eclipse?

Totality, which occurs when the moon lines up perfectly with the disc of the sun and blocks it out entirely, will begin in Russia around midday before sweeping eastward across the Arctic ocean. It will pass just south of the North Pole and make landfall in northeastern Greenland just after 4.00pm local time.

The shadow will then rush along the eastern coast of Greenland at a speed of more than 3400 kilometres per hour. The maximum length of totality will be about 2 minutes and 18 seconds, as the moon’s shadow crosses from Greenland into the Atlantic ocean. It will cross to Iceland, at which point the eclipse will become visible from more heavily inhabited areas – everywhere it will have passed so far is home only to small villages, research stations and those specifically making the journey to see the eclipse. In Reykjavík, though, totality will be visible for just over one minute at 5.48pm local time. This is the first time a total eclipse has been visible in Iceland since 1954, and the last time one will be visible there until 2196.

After skimming the western coast of Iceland, the total eclipse will make another ocean crossing and reach land again in northern Spain just before 8.30pm local time, grazing the northeast corner of Portugal and crossing the Balearic Islands off Spain’s east coast before the sun sets and the eclipse is over.

What happens during a total solar eclipse?

During totality, when the disc of the sun is completely concealed by the moon, temperatures on the ground rapidly drop by several degrees and daytime transforms into twilight. The stars and the outer reaches of the sun become visible. Usually, the sun’s outermost layer, the corona, is completely lost in the glare from its far brighter inner regions, but when those are blocked out, its shimmering sheets of extraordinarily hot plasma become briefly visible to the naked eye. In all other phases of the eclipse, it is crucial to wear eclipse glasses or use a solar filter while looking directly at the sun to prevent eye damage, but during totality it is safe to look at the corona.

That is precisely what many solar scientists will be doing during August’s eclipse. Total eclipses mark a valuable opportunity to observe the corona and try to unravel its many mysteries, including why it is so much hotter than the sun’s surface.

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While the total eclipse will be short and only visible in a few areas, a partial eclipse, with the moon taking a “bite” out of the sun, will last much longer across about a quarter of the entire planet. In many locations across the northern US, all of Canada, much of Europe and northwestern Africa, the partial eclipse will last more than an hour. It won’t be as dramatic as a total eclipse – the corona will not become visible, and the ambient light levels and temperatures won’t drop as dramatically – but will be watchable for many more people. During a partial eclipse, eye protection is needed the whole time. If you don’t have eye protection, there are several ways to watch the eclipse without looking directly at the sun, including using a pinhole camera or even natural shadows to create a projection of the sun’s shape as the moon passes in front of it.

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