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An Orrery is a clockwork model of the solar system (named after the 4th Earl of Orrery, for whom one of these was made).
That device is called an "orrery", a very strange word indeed. The word is derived from the name of Charles Boyle, 4th Earl of Orrery.
Orrery
the orrery is a plug-in which means it has to be downloaded
The plural of orrery (mechanical model of the solar system) is orreries.