The Antikythera Mechanism was a wooden box about the size of a shoebox. You operated it by rotating a handle on the side. Through a set of gears hidden away in inside, this motion turned a set of pointers on the front; and two pointers on the back.

These were the "graphical output devices" of their day. One of the pointers on the front showed the Sun's motion. Another tracked the Moon across the sky, including its inconstant speed around the Earth; and the tip of the pointer was a half-silvered ball, rotating to show the Moon's phases. There may have been other pointers showing the motion of the planets, as well.

The dials on the back (left) are not simple circles. They are spirals, with a pointer that moved outwards as it moved round. The top dial reveals the progress of the months. The lower dial is a computer that predicts that rarest of astronomical events – an eclipse of the Sun or Moon.

Look inside, and you’'ll find the incredible machinery that makes this ancient computer so precise. The Antikythera Mechanism is driven by 30 gearwheels, each precision-cut by hand – the biggest boasting 223 teeth.

Who made this incredible device – and when? Read on to find out more...