The Antikythera Mechanism
An ancient Greek geared device, recovered in 1901 from a shipwreck off the island of Antikythera, that mechanically modelled the movements of the Sun and Moon and predicted eclipses. It is the oldest known analogue astronomical computer.
What it was
Recovered by sponge divers in 1901 and dated to roughly the second century BCE, the mechanism is a case of bronze gearwheels — dozens of them — turned by a hand crank. Nothing of comparable complexity survives from the ancient world for more than a thousand years afterward.
What it did
Its dials tracked the position of the Sun and Moon through the zodiac, showed the phase of the Moon, and followed the long calendrical cycles the Greeks knew — the Metonic cycle of nineteen years and the Saros cycle by which eclipses repeat. In effect it packed a working model of the sky into a box you could hold.
Why it matters
The mechanism is hard evidence that ancient astronomers did not merely observe the sky but encoded its repeating cycles into precise machinery — the same impulse, two millennia early, behind an instrument like Moonlit.
Connections
- The Metonic Cycle — A period of about nineteen years after which the phases of the Moon fall on very nearly the same days of the solar year. 235 lunar months are almost exactly nineteen solar years — a near-perfect reconciliation of the Moon’s months with the Sun’s year.