Antikythera mechanism

Dithered illustration of Antikythera mechanism

The Antikythera mechanism is a Greek bronze gearbox, built more than 2,000 years ago, that predicted eclipses. Nothing as complex is known for a millennium, and it survives only because it sank.

Babylonian astronomers found arithmetic cycles that forecast eclipses. Someone in the Greek world turned such cycles into bronze gearing, with teeth about a millimetre long. The machine was made between about 200 and 100 BC; astronomical clocks of comparable sophistication appear only in the 14th century, at least 1,400 years later. It exists because it sank, in a Roman wreck off Antikythera dated to 70–60 BC. Nothing else like it survives from antiquity: on land, a broken bronze machine was probably melted down for its metal.

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