In China, tradition dictates that huge drums are beaten and rituals staged in an attempt to scare away the dragon that has eaten the sky. In India, pregnant women are sent indoors to avoid the shadow that could cause bad luck to those that are underneath it. And across the world, people have taken to social networks in advance of the latest solar eclipse this week.
It has been trending on social networks and was one of the most popular searches on Google all this week. But it’s just the latest manifestation of an ancient fear of and fascination with eclipses.
On 21 August, the sun will disappear from the sky across the US.
Soon after, hopefully, it will return. But we’ve not always been so sure that it will — and that’s one of the reasons that eclipses have retained some of their wonders.
Eclipses are relatively scarce, coming a few times in a century. Most people alive today might be able to remember the last big one — in 1999 — but when life expectancies were shorter, and people were less easily able to talk to other people, it’s likely that memories of eclipses didn’t go back very far.
That would have meant that any time they happened would have been a mysterious, inexplicable and unexpected event. And they still retain that power: the eclipse in the UK 1999 was hailed in a once-in-a-lifetime experience entirely.
But they’re now also more predictable. A holiday booked to see the Northern Lights, for instance, is a risk — you can head up towards the Arctic and never see a thing. But as long as the weather holds out, the sun, moon, and Earth will definitely arrange themselves into an eclipse on Friday.
We haven’t always been so sure when eclipses would arrive. Until about 500BC, when Greek scientists became able to predict an eclipse of the sun, people couldn’t know when or why exactly they would happen.
“Imagine a culture in a flat land, such as Babylonia, or eastern China, in 1,500 BC,” says Allan Chapman, a historian of science-based at the University of Oxford. “You already believed that the astronomical bodies were deities that interfered with our lives and that the sun was the source of heat and life, and then it vanishes or has a big chunk bitten out of it. Help!!!!”
The astronomical bodies were presumably worshipped at least in part not just because of theology — the sun and the moon rule everything around us, changing the tides and the rhythms of our lives. The sun is perhaps one of the most familiar sights in the world — and human lives have been lived around its rhythms since the beginning of time — but eclipses make it unusual again.
“Because the sun itself disappears from the sky, it looks like this totally strange object,” says Nigel Henbest, a British astronomer who describes the first time he saw a solar eclipse as a gobsmacking, visceral experience. “Because the sun is taken away, it becomes a black thing with these fronds around it, and looks like a Chinese dragon light.”
In some areas of East Asia, drums are beaten and rituals carried out to ensure that the sun is returned to the sky. (And it would seem to work: the sun is always restored, after all.) Elsewhere, they thought to herald doom.
“Eclipses are thought to be unlucky in India,” says Nigel Henbest. “People will hide indoors and pregnant women especially will be kept from an eclipse.
“As a scientist, this is very sad. People in India were told by religious authorities that they’re unlucky — so this could be happening and you’re told not to look at it.”
A fuller scientific understanding of eclipses in the western world came around 500 BC when a Greek philosopher called Thales of Miletus predicted an eclipse.
About 400 years later, Greek scientists built a computer out of bronze and using gear wheels. In it, you could see the sun and the moon moving around on pointers, and a dial on the back predicted eclipses.
That was one of the first uses of the technology that would eventually become modern computing. “We all think clockwork didn’t come along until thousands of years later, but the Antikythera was found in 1900 on the seabed off the island it was named after,” says Nigel Henbest, who chronicles the beginnings of astronomy in a new book, The Astronomy Bible, written with Heather Couper. The small machine was about the size of a shoebox and had dozens of handcut wheels — the interest “goes back a long way”, as Henbest notes.
But even as we have come to understand how and why eclipses happen, they have continued to be mysterious. Even when we know what’s going on, they are held to be messages of some kind.
Allan Chapman says: “Even during classical and medieval times, when Ptolemaic astronomy, the spherical earth, and sky were fully understood, it was still believed that the heavens were significators, relating to things on earth, and even given by God to act as human warnings.”
(This understanding of eclipses and other celestial phenomena as warnings haven’t gone away entirely. Some Christian pastors have said that Friday’s eclipse is a message from the heavens.)
Understanding why eclipses happen hasn’t removed any of their power — judging by the interest in this week’s, they hold as much excitement for us as ever. That might partly be the vestigial traces of the fear and fascination of our ancestors, but it is also a consequence of human curiosity.
“I think that one major factor in the entire human equation is a sense of wonder,” says Allan Chapman. “Without it, we would be goldfish.”
“I think that it was this fascination with mysteries, and their ability to excite powerful reactions within us, that not only stimulated the people of 2,000 BC to look at the sky for divinatory purposes, or make a racket to – predictably – frighten away a devouring sky monster, but which also drives our compulsion ‘to know’ today.”
This article was originally published to mark the 2015 eclipse in the UK. It has been re-published ahead of the total solar eclipse in the US – especially given that some conspiracy theorists are suggesting once more that the event is going to mark the end of the world, despite the fact that it almost certainly won’t.