you can read the full article at io9.com, but here’s the gist:
The findings, published in Nature, are probably best described as “mind blowing.” Devices with this level of complexity were not seen again for almost 1,500 years, and the Antikythera mechanism’s compactness actually bests the later designs. Probably built around 150 B.C., the Antikythera mechanism can perform a number of functions just by turning a crank on the side.
Using nothing but an ingenious system of gears, the mechanism could be used to predict the month, day and hour of an eclipse, and even accounted for leap years. It could also predict the positions of the sun and moon against the zodiac, and has a gear train that turns a black and white stone to show the moon’s phase on a given date. It is possible that it could also show the astronomical positions of the planets known to the ancients: Mercury, Venus, Mars, Jupiter and Saturn.
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The true genius of the mechanism goes beyond even the complex calculations and craftsmanship of a mechanical calendar. For example, the ancients didn’t know that the moon has an elliptical orbit, so they didn’t know why it sometimes slowed or sped up as it moved through the zodiac. The mechanism’s creator used epicyclic gears, also known as planetary gears, with a “pin-and-slot” mechanism that mimicked this apparent shifting in the moon’s movement. This use of epicyclic gears is far ahead of what anyone suspected ancient technology was capable of. Scientific American has a two-part video about the mechanism and the imaging techniques used in the research.