Description
Replica of an 18th century Grand Orrery
Replica completed in 1995
Label written by Don Unwin, the maker of this replica

An orrery is defined by the Oxford English Dictionary as "a mechanical representation of the solar system". As such, orreries traditionally show the Sun, Mercury, Venus and Earth with the Moon. A 'grand' orrery will also include outer planets known at the time of construction, fir example Saturn and Jupiter.

As can be seen in this replica, a central sphere represents our Sun, around which the planets Mercury, Venus, Earth with its Moon, Mars, Jupiter and Saturn move around on their orbits. This orrery is a replica of one built around 1750, by which time four satellites of Jupiter and five of Saturn were known, and these are also present on the orrery. When running all of these rotate around the Sun at the correct relative speeds, with the Moon and satellites also orbiting around their planets. The outer planets - Uranus, Neptune and Pluto - are not included, as they were not known in 1750.

The first orrery was made about 1710 and is signed by the famous clockmakers Thomas Tompion and his nephew George Graham, though it was almost certainly the sole work of Graham. The London instrument maker John Rowley is believed to have seen Graham's orrery shortly after it was completed and in 1716 made a similar one for Charles Boyle, forth Earl of Orrery. In honour of the owner the instrument was called an orrery, and this name has been used ever since. An example of an original 18th century grand orrery can be seen next door in the Main Gallery.
16/03/2023
Created by: Guey-Mei Hsu on 16/03/2023