Orrery

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An orrery is a mechanical device that illustrates the relative positions and motions of the planets and moons in the solar system in a heliocentric model. They 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 the arms.

Contents

History

According to Cicero, the Greek philosopher Posidonius constructed an orrery, possibly similar or identical to the Antikythera mechanism,[citation needed] that exhibited the diurnal motions of the sun, moon, and the five known planets. Cicero's account was written in the first century BC.

The Antikythera mechanism may be considered one of the first orreries. It is an ancient mechanical calculator (also described as the first mechanical computer) designed to calculate astronomical positions. It was discovered in an ancient shipwreck off the Greek island of Antikythera, between Kythera and Crete, and has been dated to about 150-100 BC. Technological artifacts of similar complexity did not appear until a thousand years later.[citation needed]

The first modern orrery was built circa 1704 by George Graham and Thomas Tompion.[1] Graham gave the first model (or its design) to the celebrated instrument maker John Rowley of London to make a copy for Prince Eugene of Savoy. Rowley was commissioned to make another copy for his patron Charles Boyle, 4th Earl of Orrery, from which the device took its name.[2] This model was presented to Charles' son John, later the 5th Earl.

Joseph Wright's picture "A Philosopher giving a Lecture on the Orrery in which a lamp is put in place of the Sun" (ca. 1766) which hangs in Derby Museum and Art Gallery, features a group (three men, three children, and a lone woman) listening to a lecture by a 'natural philosopher'—the only light in the otherwise darkened room is from the "sun" in the brass orrery, which, in this case, has rings that cause it to appear to be similar to an armillary sphere. The demonstration was thereby able to cover eclipses.[3] Shoemaker John Fulton of Fenwick, Ayrshire, built three between 1823 and 1833 - the last is in Glasgow's Kelvingrove Art Gallery and Museum.

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