Rowleys original orrery, 1712-13.

UNITED KINGDOM - FEBRUARY 18: This planetary model was made by the London instrument maker, John Rowley. Called an orrery, or more correctly a tellurium, it is a demonstration device to show the motions of the Earth and Moon around the Sun. Such devices became popular during the 17th century, especially after Sir Isaac Newton (1642-1727) published his universal theory of gravity in 1687. This particular example was made for Charles Boyle, the fourth Earl of Orrery in Ireland. Rowley copied it from an earlier example made by the famous London clockmaker George Graham (1673-1713) for Prince Eugene of Savoy. Much admired in its day, it was given the title, �orrery� after its owner, a name that was subsequently applied to later planetary models or machines. (Photo by SSPL/Getty Images)