Orrery

An orrery is a mechanical model of the Solar System that shows or predicts the relative positions and motion of the planets and moons, typically built around a central sun with planets carried on mechanical arms driven by clockwork. Mechanical models of the heavens go back a long way, and the Antikythera mechanism, recovered from a Greek shipwreck and dated to between 205 and 87 BC, is considered one of the earliest such devices, showing celestial motion according to the geocentric view of its time. In 1348 the medieval scholar Giovanni Dondi built what is described as the first known clock driven mechanism of this kind, showing the positions of the major planets according to Ptolemaic theory. The modern name comes from an instrument built around 1710 by clockmakers George Graham and Thomas Tompion, copied soon after by instrument maker John Rowley, whose patron Charles Boyle, the fourth Earl of Orrery, commissioned a version around 1712 that gave the device its English name.