Orrery

This article is about the mechanical device. For the Irish peerage, see Earl of Orrery. For the Irish kingdom and barony, see Orrery and Kilmore.
A small orrery showing Earth and the inner planets

An orrery is a mechanical model of the Solar System that illustrates or predicts the relative positions and motions of the planets and moons, usually according to the heliocentric model. It may also represent the relative sizes of these bodies; however, since accurate scaling is often not practical due to the actual large ratio differences, it may use a scaled-down approximation. The Greeks had working planetaria, but the first modern example was produced c. 1712 by John Rowley.[1] He named it "orrery"[2] for his patron Charles Boyle, 4th Earl of Orrery (in County Cork, Ireland). The plaque on it reads "Orrery invented by Graham 1700 improved by Rowley and presented by him to John [sic] Earl of Orrery after whom it was named at the suggestion of Richard Steele."[3][4]

Orreries are typically driven by a clockwork mechanism with a globe representing the Sun at the centre, and with a planet at the end of each of a series of arms.

  1. ^ "Orrery made by John Rowley for the Earl of Orrery | Science Museum Group Collection".
  2. ^ "Oxford English Dictionary". oed.com. Retrieved 11 July 2024.
  3. ^ King, Henry C.; Millburn, John R. (1978). Geared to the Stars: The Evolution of Planetariums, Orreries, and Astronomical Clocks. Toronto: University of Toronto Press. p. 382. ISBN 9780802023124. Retrieved 1 November 2024. [...] inscription on a brass plaque attached to Rowley's orrery, which reads: 'Orrery invented by Graham 1700. Improved by Rowley and presented by him to John Earl of Orrery, after whom it was named at the suggestion of Richard Steele.'
  4. ^ Compare: Buick, Tony (26 October 2013). Orrery: A Story of Mechanical Solar Systems, Clocks, and English Nobility. Astronomers' Universe. New York: Springer Science & Business Media. pp. 87–88. ISBN 9781461470434. Retrieved 1 November 2024. While the model was with Rowley, he was commissioned by the Earl of Orrery to make a copy for him, and Rowley then named the model an orrery after his patron. [...] It had been suggested that Sir Richard Steele (Irish essayist, 1672-1729) came across Rowley's model in a presentation delivered by Rowley and, knowing nothing of the Graham model, named it an orrery in honor of the Earl of Orrery to popularize it. [...] the lecturer and writer Desaguliers (1683-1744) [...] attribute[d] the actual naming of the orrery to Steele when it was, quite possibly, Rowley [...].