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.

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Becky Smethurst is an astrophysicst at the University of Oxford and her work looks at how these behemoths affect the galaxy around them. �鶹��ý‘s digital features editor, Jacklin Kwan, sat down with her to discuss what black holes are, how the supermassive ones get so big and Smethurst’s amazing career.

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Western Europe’s first total solar eclipse since 1999 will happen on 12 August and see eclipse chasers travel to eastern Greenland, western Iceland and northern Spain for totality, when the moon covers the sun’s disc and the usually hidden solar corona bursts into view. Solar and atmospheric scientists will be among them – and above them.

It is tempting to think total solar eclipses have been made obsolete for scientists by spacecraft. NASA’s Parker Solar Probe has flown through the sun’s corona, while the European Space Agency’s Solar Orbiter and study the sun from space. can even create artificial eclipses in orbit. So why do scientists still need to chase the moon’s shadow across Earth?

The answer is simple: total eclipses offer cheap and accessible opportunities to study both the sun and Earth. “Research groups that have novel ideas can go to an eclipse and take observations without having to bid for tens of millions of pounds’ worth of grants from NASA or the European Space Agency – the barrier to entry is much lower,” says , a solar physicist at the Laboratory for Atmospheric and Space Physics in Boulder, Colorado.

One example is the , which will send teams from several US universities to Spain and Iceland to study atmospheric responses to the eclipse. Balloons released in Spain will reach an altitude of 27 to 37 kilometres, carrying 360-degree cameras, ozone instruments and radio experiments. Icelandic teams will launch balloons carrying radiosondes, devices that can monitor pressure, temperature, humidity and other atmospheric parameters. The idea is to measure the effects the eclipse has on the planetary boundary layer, the atmosphere’s lowest region where its behaviour is most heavily influenced by warm air rising from the ground.

NASA’s WB-57 high-altitude aircraft can measure polarised coronal light and will fly for the 2026 eclipse. Flying high avoids the problem of cloud cover obscuring the view, while also minimising atmospheric interference. “At high altitude, you can observe infrared light that you can’t observe from the ground,” says French.

During the 2024 total solar eclipse, – an experiment funded by the US National Science Foundation and NASA – used telescopes spread along the path of totality to create a 1-hour timelapse of the corona. This will be repeated during the 2026 eclipse, ahead of a plan to produce a timelapse of the corona with the larger experiment during the longer eclipse that will happen in August 2027. Totality in 2027 will last much longer because the new moon will be closer to Earth, and the path of totality is close to the equator, where Earth effectively bulges out towards the moon.

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“Most of the scientific instruments at an eclipse are not just taking photographs, but collecting measurements of spectra,” says French. Spectroscopy can reveal the speed, temperature and density of plasma in the corona. “When you observe specific spectra, this can give you information on the speed of plasma moving in the sun, and can tell you about the temperature and the density of plasma sloshing around the sun,” he says.

Other eclipse scientists ask a fundamental question: what is the radius of the sun? Because the sun has no solid surface, its visible edge is difficult to define. Yet tiny differences can shift the predicted edge of the path of totality. The , a group of researchers scattered across the world, records flash spectra at the path’s edge to refine eclipse maps and calculate the sun’s actual radius.

The eclipse may also offer a rare chance to test whether aurora can be detected during totality. NASA scientist , founder of citizen science project , will use all-sky cameras to search for faint auroral glow. It is a long shot, but Iceland lies beneath the auroral oval, a region surrounding the geomagnetic North Pole within which the aurora can regularly be seen. Even a non-detection could help constrain whether eclipse darkness can reveal aurora.

Total solar eclipses are brief, vulnerable to clouds and geographically specific, but they open a rare observing window onto the sun’s inner corona – and let scientists try bold ideas without first building a spacecraft.

Discovery Tours: Eclipses

Explore our tours and cruises designed to help you make the most of experiencing awe-inspiring solar eclipses in handpicked locations around the world.

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