Image taken from: blogspot.com
The Orrery -
By Definition an orrery is a mechanically driven astrological model in which the planets revolve around a stationary sun.
This example built by Mr. Murray Keir in Australia, uses SDP Gears to bring the orrery to life. Check out the blog which includes a detailed list of the parts you will need to make your own orrery.
Parts Used in the Orrery