An Orrery is a mechanical model of the Solar System that shows where the planets sit relative to one another and how they move. Most run on clockwork, with a globe for the Sun at the centre. In a wristwatch, the same idea becomes a planetarium module that turns each planet at its actual pace.
Where it comes from
The clockmakers George Graham and Thomas Tompion built an early orrery around 1710. In 1712 a London instrument maker named Rowley built a small device that reproduced the motions of the Earth and Moon. It followed a design by Graham. Rowley’s patron was Charles Boyle, 4th Earl of Orrery, and the device took its name from his title. The word itself dates only from 1714.
How does a planetarium watch work?
A planetarium watch brings the orrery down to wrist size. Inside the module, stacked discs share one centre. Each disc carries a planet and turns at that planet’s actual pace. Ulysse Nardin brought out its Planetarium Copernicus in 1988. It shows where the five main planets are. Christiaan van der Klaauw followed in 1999 with its Planetarium wristwatch, which shows six planets moving around the Sun in real time. In 2014 Van Cleef & Arpels released a watch built on planetarium modules ordered from Christiaan van der Klaauw.
Not to be confused with
Every orrery is a planetarium in the older sense of a mechanical model of the planets. Today, though, planetarium more often means a domed theatre, so orrery is the clearer word for the mechanical model. A tellurion, also called a tellurium, is a different device. It shows only the Sun, Earth and Moon. A lunarium is another related device. It concentrates on how the Moon moves around the Earth.
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