The 223-Tooth Gear: How Ancient Greeks Predicted Eclipses
The Antikythera Mechanism contains a gear with exactly 223 teeth — and that number is not arbitrary.
The Saros Cycle
Ancient Babylonian astronomers discovered that eclipses repeat in a cycle of 223 synodic months (approximately 18 years, 11 days, and 8 hours). They called this the Saros cycle.
The Greeks encoded this directly into bronze. One full rotation of the 223-tooth gear = one complete Saros cycle. Every tooth represents one lunar month. Every rotation predicts the next sequence of solar and lunar eclipses.
Why This Matters
This wasn't mysticism. This was mechanical computation. Over 2,000 years before digital computers, someone built a device that could:
Predict solar eclipses to within hours
Track the Moon's irregular orbit using a pin-and-slot mechanism
Account for the 5.1° tilt of the lunar orbital plane
The Gear Count Problem
The mechanism contains 30+ interlocking gears, and scholars still debate the exact count. Fragment A alone contains the main drive train. Fragments B through G reveal subsidiary dials for the Metonic cycle, Callippic cycle, and Olympiad tracker.
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