The Antikythera mechanism is a clock-like device that consisted of 30 gears. It was mainly designed to calculate the positions of the sun, moon, planets and lunar/solar eclipses.

The Antikythera mechanism provided astronomical positions by entering past or present dates. It worked by moving the main crank, which was attached to small and large gears. This is turn set the year on it, where each rotation of the crank is equivalent to 78 days. Although the exact operation of Antikythera mechanism is yet to be understood, the crank movement also moved the internal gears that helped in calculating the position of the moon, sun, calendar dates, cycles and other astronomical objects.