Jun 09, 2017 I Micah Hanks

Blackout: Strange Phenomena That Occurs During Solar Eclipses

This August 21, 2017, a rare total eclipse of the sun will be visible across much of the United States. Already being dubbed as "The Great American Total Solar Eclipse," it is expected to be seen across the country in a line crossing roughly between Oregon and South Carolina, as the sun disappears behind the moon, resulting in a sudden drop in temperature and the temporary onset of twilight.

Throughout history, a variety of mythological interpretations existed about what caused solar eclipses. For instance, in ancient China, it was often professed that a massive dragon had eaten the sun; hence why the ancient Chinese word for eclipse-- chih--also means "to eat."

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Eclipse photographed by the crew of Apollo 12.

Apart from traditional beliefs about eclipses, there are a number of different unusual phenomena that have been observed during eclipses as well. For instance, the so-called "eclipse shadow-band anomalies" that occur as the sun passes behind the moon have been recorded by astronomers over the years. Researcher J.L. Codona described them thusly in a 1991 article in Sky and Telescope:

"[The bands resemble] mysterious gray ripples are sometimes seen flitting over the ground within a minute or two of totality. The bands are initially faint and jumbled; but as totality approaches, they become more organized, their spacing decreases to a few centimeters, and their visibility improves. After totality ends the bands can reappear and become progressively fainter and more disorganized until they disappear. Shadow bands seem to move perpendicularly to their length, but this is only an illusion. It stems from a lack of features that allow the eye to track motion along the length of the bands." 

It was suggested by Codona that this particular anomaly may likely result from a "twinkling effect" resulting from the appearance of the solar crescent that appears very thinly just prior to, and immediately after, the total coverage of the sun by the passing moon. Codona said the focal source of the light anomaly was likely atmospheric "turbulence" as little as a few hundred feet above ground.

Another unique phenomenon associated with eclipses is the "Allais effect", in which minor changes in the behavior of a Foucault pendulum occur as the sun passes behind the moon. In 1954, economist Maurice Allais was experimenting with pendulums over the course of a 30-day period, during which he observed and recorded their movements.

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Allais at work with his pendulums.

During this time, an eclipse of the sun occurred, under which conditions Allais noticed that the movement of the pendulum appeared to quicken; although the effect was very minor, it was nonetheless noticeable, and has allegedly been reproduced several times over the years, despite there being controversy over what, precisely, causes the so-called Allais effect.

Going back to ancient times, on at least one occasion in history an eclipse was even believed to have brought an end to a war. In his Histories, Herodotus wrote of a prediction made by Greek philosopher Thales, who lived between 624-547 BCE, that a solar eclipse would occur on the date of May 28, 585 BC.

According to Herodotus, “day was all of sudden changed into night. This event had been foretold by Thales, the Milesian, who forewarned the Ionians of it, fixing for it the very year in which it took place. The Medes and the Lydians when they observed the change, ceased fighting, and were alike anxious to have terms of peace agreed on.”

Though the celestial event brought an end to the conflict between the Lydians and the Medes, it is well known that the ancient Greeks studied solar eclipses and other celestial phenomenon, and were adept at predicting them.

Obviously, while people in the ancient world were fascinated--and often frightened--by solar solar eclipses, these rare celestial phenomena are still very intriguing to us today, and even manage to boast a few unanswered questions. For more information about the upcoming 2017 solar eclipse, and where it can be seen, check out Space.com's full rundown about it here.

Micah Hanks
Micah Hanks is a writer, podcaster, and researcher whose interests cover a variety of subjects. His areas of focus include history, science, philosophy, current events, cultural studies, technology, unexplained phenomena, and ways the future of humankind may be influenced by science and innovation in the coming decades. In addition to writing, Micah hosts the Middle Theory and Gralien Report podcasts.

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