Detail of the planetary model made by the London instrument maker Thomas Wright (d 1767). Called an orrery or planetarium, it is a demonstration device to show the motions of the Earth and Moon around the Sun. This example has a wooden drum base with a hand painted plate and bras calendar ring supported on pillars. Such devices became popular during the 17th century, especially after Sir Isaac Newton (1642-1727) published his universal theory of gravity in 1687. To reproduce the motions of the solar system this model employs a hand crank to drive the gear wheels. This type of orrery would have been commonly employed at public astronomy lectures.
© Science Museum / Science & Society Picture Library