When the sky goes dark at mid-day, people notice. Because some observers wrote down what they saw, and because the clockwork of the heavens is so precise, historians can nail down important dates for chronological research.

Human responses to eclipses are interesting to think about. These cosmic events are rare enough for any spot on the earth to strike fear and wonder in the eyes of anyone unfamiliar with their causes. Joe Rao relates the story at Space.com about how Christopher Columbus, aware of an approaching lunar eclipse in 1504 via his mariner’s almanac, told uncooperative natives in Jamaica that his God had the power to darken the moon unless they provided food for his crew. Even if the impact of this magic trick was short-lived, one can imagine the look in the native chief’s eyes when Columbus delivered on his promise. That was a lunar eclipse, of course, which is much more common, and viewable over a wider area. Mark Twain picked up on the “eclipse trick” and used a fictionalized solar eclipse to similar effect in his humorous novel, A Connecticut Yankee in King Arthur’s Court.

Joking aside, solar eclipses have been tremendously valuable for nailing down chronologies in ancient cultures. Because they can be post-dated to the second for any spot on the planet, they provide a “golden spike” for timelines whenever they have been recorded by eyewitness accounts. Some readers may have seen planetarium shows where the lecturer turns the clock back to a view of the sky and planets for any date in history. With a little geometry, it’s not difficult to indicate exactly when and where a historical eclipse was visible. The Greeks got pretty good at predicting eclipses, and even ancient Babylonians gained a crude understanding of the “Saros Cycle” that gives some expectation of when they are likely to occur because of the oscillating inclination of the moon’s orbit.

There are complications, however, before precise timelines can be inferred. One is that written accounts may be flawed. An observer may be recounting what a predecessor saw. It’s not always possible, additionally, to correlate behaviors of nations with astronomical events. With those caveats in mind, here are ways that eclipses have helped historians.

Ireland, 3340 BC: The NASA Eclipse website describes a total solar eclipse that occurred in Ireland on November 30, 3340 BC. This may have prompted construction of a megalith that matches the geometric relationships of the stones.

China: The NASA page mentions an eclipse during the reign of Emperor Chung K’ang (2159-2146 BC), who was alarmed by the noise of townspeople beating drums to scare away “the dragon that was eating the sun.” He promptly beheaded his court astronomers for not predicting the event. An ancient Chinese record of another eclipse that occurred October 22, 2134 BC, when translated, seems to say “the Sun and Moon did not meet harmoniously.”

Babylon, July 31, 1063 BC: The next notable eclipse recorded on Babylonian clay tablets dates to 1063 BC. It “turned day into night.” Another famous eclipse occurred in 763 BC. Court astronomers were starting to get a handle on the predictability of eclipses:

By carefully noting local lunar and solar eclipses, Babylonian astronomers were able to predict lunar eclipses and later, solar eclipses, with a fair accuracy. Their tool was the so-called Saros-cycle: this is the period of 223 synodic months (or 18 years and 11.3 days) after which lunar and solar eclipses repeat themselves…

There are many stories of how eclipses have been used to foretell important political events, and for nearly all human civilizations with a recorded history, total solar eclipses were regarded with fear and dread prior to the advent of mathematical schemes for predicting when they would occur.

Greece, April 6, 647 BC: The poet Archilocus attributed the darkening of the sun to the power of Zeus. By 460 BC, Greeks were getting good at predicting eclipses. Herodotus records that Thales was able to predict the year when a total eclipse would occur. The eclipse he predicted took place in either 610 or 585 BC, but details of his method of prediction have not survived. By 150 AD, Ptolemy had constructed a sophisticated system or predicting solar and lunar eclipses.

There are suggestions of eclipses in the Old Testament prophetical books of Joel and Amos, but these are not precise enough to correlate with specific events. These prophets could have witnessed lunar eclipses or heard about them. Those wishing to delve into more detail might consult Solar and lunar eclipses of the ancient Near East from 3000 B.C. to 0 with maps by Kudlek and Mickler (Stanford, 1971).

NASA’s eclipse history page ends with a table of scientific discoveries made during eclipses from the period 334 to 1919 AD. See our previous article about ongoing scientific discoveries made possible by this “coincidental” alignment of the sun and moon.

Veteran eclipse hunter Fred Espenak has documented “Solar Eclipses of Historical Interest” at the NASA Eclipse Website. His well-documented chart includes dates, locations, type of eclipse, and quotes from written records, dating from 2136 BC to the future eclipses of 2017 and 2024, with links for further information.

Eclipses and God-of-the-Gaps

Some of the ancient eclipses occurred near in time to battles or plagues, leading kings to mistakenly read divine support or displeasure with their activities. Today we understand eclipses very well. We no longer fear them, or comets, or other astronomical events as bad omens. Some scientists use the progress in knowledge about eclipses as support for the “god-of-the-gaps” position: i.e., as scientific knowledge progresses, the “god hypothesis” becomes increasingly superfluous.

That argument, however, cuts both ways. The more we understand about probability, the less plausible it sounds to appeal to “coincidence-of-the-gaps” thinking when multiple, independent factors appear to converge on design. The chance hypothesis has been falsified by the discoveries of modern science. It is no longer tenable to appeal to coincidences recklessly for cosmological fine-tuning, the earth’s habitability, the origin of life, the origin of multicellularity and sex, the origin of complex body plans, the origin of consciousness, and the origin of reason and morality. Each of these provides positive evidence for intelligent design. Collectively, they render the chance hypothesis improbable by many, many orders of magnitude.

Photo: Viewing an eclipse, January 24, 1925, by Harris & Ewing photo studio [Public domain], via Wikimedia Commons.