Orrery

Orrery

Astronomy,Natural Philosophy

This orrery, a model which shows how planets revolve around the sun, is on display at the School of Physics and Astronomy. It was built by Benjamin Cole of London between 1748 and 1760. The four inner most planets are mounted on plates and connected to a mechanism which allows them to rotate about the sun at their correct rates. Jupiter and Saturn are attached to arms extending outside the main structure which allow them to rotate freely. The base of the orrery has 12 windows instead of wooden panes so that the interior mechanism to be viewed. Twelve beams support a ring which encircles the inner planets and is engraved with the signs of the Zodiac and the Julian and Gregorian calendars. The ring serves as the base for a model of part of the celestial sphere. The elevated and angled rings forming the ‘dome’ represent the ‘Artic’ Circle, the Tropic of Cancer, and the Equator.

mathematicalycurious

sjv1@st-andrews.ac.uk

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