Celebrating Halley’s Eclipse On Its 300th Anniversary

For millennia, humans were terrified of solar eclipses. On May 3, 1715, Edmond Halley proved they had nothing to fear.

May 3 2015, 11:26pm

Total solar eclipse. Image: NASA Goddard Space Flight Center

Exactly 300 years ago today, a total solar eclipse graced the skies of northern Europe and Asia, plunging the day into darkness.

For millennia, these rare astronomical events were considered to be divine portents of doom, a warning of ill fortune and civil turmoil to come. But the total eclipse of May 3, 1715 ended up with a very different role in history, thanks to the efforts of brilliant scientists like Edmond Halley, after whom this event—Halley's Eclipse—is now named.

The path of Halley's Eclipse over England. Public Domain

As opposed to perpetuating the superstitions surrounding eclipses, Halley demonstrated how Newtonian physics not only explained them, but made it possible to predict exactly when they would occur, and how long they would last. He used the accuracy of his predictions, and those of other Newtonian advocates, to persuade people that seemingly supernatural events are explicable through science.

"The sudden darkness, wherein the stars will be visible about the Sun, may give no surprise to the people, if unadvertised, be apt to look upon it as Ominous, and to interpret it as portending evil to our Sovereign Lord King George and his Government, which God preserve," wrote Halley of the May 3 eclipse.

"Hereby they will see that there is nothing in it more than natural, and no more than the necessary result of the motions of the Sun and Moon; And how well those are understood will appear by this eclipse," he concluded.

As a longtime champion of Isaac Newton's theories—Halley was the person who first persuaded Newton to publish his revolutionary Principia—he must have felt especially vindicated by his extremely accurate prediction of this eclipse.

Natural events like comets and eclipses had been historically so inextricably linked with unfounded fear, and Halley's Eclipse dusted off all that accumulate mythological debris. For that reason alone, it is my vote for the most momentous of any total solar eclipse in history.

That said, solar eclipses have always been viewed with intrigue and wonder, and Halley's Eclipse is far from the only significant blotting out of the Sun. In fact, the superstitious side of these events can be just as fascinating as their role as a scientific riddle that was solved by Newtonian physics.

For example, the earliest recorded solar eclipse occurred on October 22, 2137 BCE, and supposedly resulted in the deaths of the two royal astronomers. So the story goes, this stargazing duo was drunk all the time, and failed to predict the eclipse due to all the revelry and hangovers.

The Emperor didn't take this oversight too well. After all, the prevailing belief was that eclipses heralded dragon attacks, and that's the kind of threat leaders are wont to take seriously. So they were duly executed, and their successors practiced extreme sobriety. This story sounds thoroughly apocryphal, but it still demonstrates the importance of these events to governance, and the severity of punishment doled out for failing to predict them.

A 1571 painting of a solar eclipse. Image: Antoine Caron

As the centuries rolled by, these surreal occultations of the Sun were further witnessed by Thales, Herodotus, Thucydides, and Plutarch. A solar eclipse on August 2, 1133 was widely believed to have presaged the death of King Henry I, prompting William of Malmesbury to write that "the elements manifested their sorrow at this great man's departure from England."

These are fantastic stories to revisit, providing a tangible reminder of how terrifying and inexplicable solar eclipses were regarded before the Scientific Revolution. Fortunately, since Halley's Eclipse, these natural events have not only been demystified, they have also become important yardsticks for testing out emerging scientific theories.

For example, the solar eclipse of July 28, 1851 inspired the first solar eclipse expedition, in which astronomers from all over Europe traveled to Scandinavia to observe the event, and to share their observations. Likewise, the solar eclipse of May 29, 1919 was used to confirm Albert Einstein's relativistic predictions, and has since been known as Einstein's Eclipse.

Indeed, solar eclipses continue to yield valuable data in the 21st century, not to mention that they still captivate the public with the otherworldly beauty of our solar system's orbital waltz.

That, I'd argue, is the real gift that Halley and his fellow astronomers passed down to us. While the stories of bad omens and supernatural import are fun to parse, the science of eclipses has dissolved our historical anxiety over these stunning events, and deepened our appreciation for the world beyond our own.