Antikythera mechanism

The Antikythera mechanism is an ancient Greek geared device, built around the 2nd century BC and recovered in 1901 from a shipwreck off the island of Antikythera, that is widely described as the oldest known example of an analogue computer. It used roughly 30 surviving bronze gears, the largest with 223 teeth, housed in a wooden case, to predict astronomical positions and eclipses years in advance and to track a four year cycle of athletic games. Modern X-ray tomography of its fragments, most thoroughly in 2005, showed the device modeled the Moon's irregular orbit and solar and lunar positions through sophisticated epicyclic gearing, a level of mechanical astronomical calculation not matched again for over a thousand years.