Ancient Greeks Built an Eclipse-Predicting ‘Computer’ 2,000 Years Ago

More than 2,000 years before the Great American Solar Eclipse, which will darken the skies over the U.S. on Aug. 21, astronomers in ancient Greece developed their own “supercomputer” to predict eclipses just like this one.

The ancient gearbox, called the Antikythera mechanism, was used to identify astronomical events that could anchor their calendar.


When explorers looked through the wreckage, they found a shoe-box-size contraption covered with dials and filled with about 30 gears made of bronze. Though the mysterious object had fragmented into dozens of pieces, archaeologists soon figured out what the enigmatic object was used for: The hand-cranked gearbox would have allowed ancient Greek astronomers to figure out the position of the sun, moon and stars at any given time in the future.

Though the mysterious astronomical calculator’s 2,000 years under the sea have corroded it, scientists have used 3D imaging to reveal some of the text on the box, which provides instructions on how to use it, according to a 2016 study published in the journal Almagest.

“Before, we could make out isolated words, but there was a lot of noise — letters that were being misread or gaps in the text,” Alexander Jones, a professor of the history of science at New York University, told Live Science last year. “Now, we have something that you can actually read as ancient Greek. We can tell what these texts were saying to an ancient observer.”

For instance, the new information reveals that there was a zodiac chart on the front of the gearbox showing the planets moving through the different constellations, the study found.

What’s more, the Greek computer was surprisingly sophisticated. The Antikythera mechanism could not only predict the timing of eclipses but also reveal characteristics of those eclipses, such as the amount of obscuration, the angular diameter of the moon (which is the angle covered by the diameter of the full moon) and the position of the moon at the time of the eclipse, the study found.

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