about

the metonic cycle is a period of nearly 19 years, corresponding to 235 synodic months or lunar phases. named after meton of athens, a greek mathematician and astronomer from the 5th century bc, the cycle provides a framework for constructing lunisolar calendars by synchronizing the solar year with the lunar month.

a mechanical lunisolar calculator, based on the metonic cycle, is integrated into the antikythera mechanism, a hand-powered model of the solar system built in the 2nd century bc. this virtual model simulates a gearing system inspired by the antikythera mechanism, following the ratio ²³⁵⁄₁₉ = ⁴⁷⁄₁₄ × ⁷⁰⁄₁₉ ≈ 12.37. the second gear ratio is ³⁵⁄₁₉ with a rotating disc covering two moon phases per full turn. the calculator deviates by one day every 60.5 years.

controls on the right allow for toggling between animation and the current moon phase, as well as step forward or backward by one day. the animation speed is set to one solar year per minute.

contact:
prof. thomas weibel
university of applied sciences of the grisons
berne university of the arts
switzerland

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