Orrery

Part of speech: noun

Pronunciation: /ˈɒɹ.ə.ɹi/

Definitions

1. A mechanical apparatus that represents the motions and positions of celestial bodies moving in orbits surrounding a central star
2. A device that mechanically displays the relative movements of planets orbiting a sun-like center
3. An instrument crafted to show the orbital paths and relative positions of planets in a simulated heliocentric system

Etymology: A planetarium model that carries the name of an Irish earl, and the earl was not even the first to be honored that way. Charles Boyle, 4th Earl of Orrery (1676–1731), had a mechanical model of the solar system made in the early eighteenth century, and the instrument was named after him. The name itself traces back much further, to Irish "Orbhraighe," originally the name of a tribe meaning roughly "Orb's people." That name came to label a territory and then a barony in County Cork, which is where the Boyle family's title came from. So the word is a double eponym: a family's title took its name from a people and their land, and the title in turn gave its name to a machine. The clockwork model was a gift of sorts to the Earl's social world, showing the planets in motion around the sun, and the instrument kept the family name long after the Earl was gone.