Grand orrery, 1733.
© Science Museum / Science & Society Picture Library
An orrery or planetarium is a demonstration model to show the motions of the Earth, Moon and planets around the Sun. Some have brass armillary bands like this example. It is not known who made this particular orrery, only that Thomas Wright made such extensive modifications in 1733 that it has since been referred to as Wright's grand orrery. The orrery, which takes its name from Charles Boyle, the fourth Earl of Orrery, became popular during the 17th century, especially after Sir Isaac Newton (1642-1727) published his universal theory of gravity in 1687.