Orrery

Webster's Dictionary

(n.) An apparatus which illustrates, by the revolution of balls moved by wheelwork, the relative size, periodic motions, positions, orbits, etc., of bodies in the solar system.

The Nuttall Encyclopedia

A mechanical toy which exhibits, by an arrangement of rods, balls, and toothed wheels, the sun, the planets, and their moons, all performing their respective motions; so named after the Earl of Orrery, for whom Charles Boyle made the first one in 1715.