But only very roughly, as it could be thousands of kilometers away from the previous observation spot. While there probably was another total solar eclipse 18 years later, it would have been over a completely different part of the planet.Īfter 54 years-three Saros cycles-the eclipse region should have returned to roughly the same position on Earth. But would you have seen a similar event 18 years later? Alas, no. If you were an ancient culture that happened to observe a total solar eclipse, you would have been very lucky indeed ( they occur roughly every 375 years at a given region on Earth). So, if you see a lunar eclipse, you can expect another one 18 years later, visible from most places on Earth. The Saros cycle represents how long it takes for the sun-Earth-moon system to return to almost exactly the same triangular configuration. The word "Saros" was referenced in the 10th-century Byzantine Suda encyclopedia, and possibly has a Greek origin ("saro" meaning "sweep", perhaps relating to how eclipses sweep across the sky). ![]() This 18-year cycle, which can persist as a sequence for over a thousand years, is now known as a Saros cycle. It was mentioned in written records by the Babylonians and Assyrians (of ancient Mesopotamia and modern Iraq), and oral tradition suggests the cycle was used for ceremonial purposes by Torres Strait Islanders in what is now Australia. Various cultures around the world have independently discovered eclipses seem to occur on an 18-year cycle. Credit: Xmoussas/Wikimedia Commons, CC BY-SA The not-so-mythical Saros cycle The Saros period (marked with a red rectangle) is visible on a fragment of the ‘user manual’ of the Antikythera mechanism. Many cultures attached foreboding to such events (like the partial lunar eclipse seen during the Fall of Constantinople in 1453) and quite reasonably wondered when the next such event might occur. Since eclipses are so startling to witness, many ancient peoples both noted their occurrence in writing and art, and discovered the repeating characteristics of such events.ĭuring a lunar eclipse, where Earth blocks sunlight that would otherwise illuminate a full moon, the dimmed moon takes on a bloody hue. In fact, explaining the moon's motion was the only problem that made Isaac Newton's head hurt. On top of this, the moon appears to rock and wobble quite haphazardly on its journey across the sky, making it extremely challenging to accurately describe its orbit. For one thing, it has phases it also grows and shrinks in apparent size as it travels on an elliptical orbit around Earth. While the sun's movement is quite simple, the moon moves across the sky with much more complexity. Naturally, they also tried to anticipate and predict their motions. But it turns out calculating exactly when and where we can watch an eclipse in its full glory can be surprisingly hard.īeing so dominant in the sky, the sun and the moon were the most captivating celestial bodies for ancient cultures to observe. Eclipses have entranced us for millennia.
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