Turning a crank handle moves all the pointers, simultaneously through gears and axleshat connect them. By selecting a date on the front 365-day dial (with the possibility of an extra leap day every four years), corresponding information can be read about the astronomical bodies on the other dials. Alternatively, the user can select an astronomical event and then see when the date will occur (or has occurred in the past).

For instance, the user can check the correspondence between the solar and the lunar calendar, the position and phase of the moon, and the eclipses that may occur for any given day of the selected month. But the most remarkable ability of the Antikythera Mechanism is to show the variable motion of the Moon, realized through an extraordinary epicyclic gear train.

(Click on the picture to watch the video!
 The video can be found at: http://www.youtube.com/watch?v=L1CuR29OajI&feature=player_embedded)