An astronomical coincidence is happening on August 12

On 12 August 2026, millions of people will witness an exceptional phenomenon: day will turn into night twice thanks to a total solar eclipse. While only those along a narrow path of the Earth will experience complete darkness, much of Europe, including the Netherlands, can still enjoy a partial solar eclipse, with the moon appearing to take a large bite out of the sun. Historian of astronomy, Rob van Gent, explains what solar eclipses are, and why they continue to inspire awe around the world. 

What is a solar eclipse?

A solar eclipse occurs when the new moon passes between the sun and Earth, and the narrow shadow cone of the moon falls on the Earth, obscuring the sun from our view from a few seconds to several minutes. Depending on how precisely the three celestial bodies align, the eclipse can be total, partial or annular.

During a total solar eclipse, the moon completely covers the sun, revealing its faint outer atmosphere, or corona. In a partial eclipse, only part of the sun is obscured. An annular eclipse takes place when the moon is too far from the Earth and appears too small to cover the sun completely, leaving a brilliant ring of sunlight around its edge.

Frequent but rare

“Although total solar eclipses occur somewhere on Earth every 18 months on average, it can take centuries before you can see one from a particular location,” says Rob van Gent. The last total solar eclipse visible from the Netherlands was on 3 May 1715. The next will not arrive until 7 October 2135. “That is why many people travel across the world to witness such an event.” 

A total solar eclipse is possible because of an extraordinary coincidence, Van Gent explains. “Although the sun is 400 times larger than the Moon, it is also about 400 times farther away, which makes them appear to be about the same size in the sky. The result is a phenomenon unique to Earth; no other planet in the solar system that we know of can offer such visual spectacle.”

A few minutes of awe

People who have witnessed totality often describe the experience as transformative. Rob van Gent, who travelled to Karlsruhe (Germany), to observe the eclipse in August 1999, says it is “an experience not to be missed.” 

“As the moon slowly covers the face of the sun, shadows grow sharper and trees project tiny crescent suns onto the ground. As it gets darker and darker, the temperature drops a few degrees, and birds go quiet or fly back to their nests as if it were nighttime,” he recalls. “Then, suddenly, the corona appears around the black disk of the moon. It is a magnificent sight.”

Research into the reactions of people during a total solar eclipse revealed a deepened sense of awe and wonder. A study of social media posts following the eclipse that crossed the United States in 2017 found that people were significantly more likely to use the word “we” than “I”, suggesting that the shared experience fostered a stronger sense of connection.  

Why is the study of total solar eclipses important?

For much of human history, total solar eclipses inspired fear and superstition. “Across many ancient cultures, the sudden disappearance of the Sun was interpreted as a celestial omen affecting kings and rulers. Whoever was in power demanded to know whether such events could be predicted. You could say that was the driving force behind the prediction of eclipses by early astronomers,” explains van Gent. 

The first recorded prediction of a total solar eclipse is attributed to the ancient Greek philosopher Thales of Miletus in 585 BCE, when a total solar eclipse is said to have interrupted a battle between the Lydians and the Medes. According to the Greek historian Herodotus, the unexpected darkness was taken as a message from the gods, leading the two armies to lay down their weapons and negotiate a peace treaty. 

As astronomy developed, eclipses transformed from ominous portents into opportunities to generate new knowledge. This was the case in the year 968, when the Byzantine historian Leo the Deacon arguably first documented the solar corona. Or during the 1868 eclipse, when the French astronomer Pierre Janssen and the English astronomer Joseph Norman Lockyer, each independently discovered a new element never seen before on Earth, which was named helium. And especially in 1919, when two British teams observed the same eclipse from two different locations, helping to test Albert Einstein's theory of relativity. 

“Before the use of space-based observatories, total solar eclipses offered astronomers the only opportunities to study the sun’s corona directly from Earth, which is normally overwhelmed by the sun’s intense light,” explains Van Gent. “Since the 1970s, we can put a satellite in orbit around the Earth and artificially block the sun’s light with a small disk, recreating eclipse-like conditions at any moment of the day. But a total solar eclipse is still a magnificent phenomenon,” he says. “If there is a total solar eclipse in your vicinity, do make the effort to actually see it. It’s a once-in-a-lifetime experience.”