Brass Orrey.
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.

http://brassorrery.blogspot.com/

Parts Used in the Orrery
  Part Number Quantity
Main gears A 1B 1-N32016 4
  A 1B 1-N32032 3
  A 1B 1-N32040 2
  A 1B 1-N32048 3
  A 1B 1-N32050 3
  A 1B 1-N32064 3
Moon rotation gears A 1B 1-N32128 1
  A 1B 1-N32010 1
Earth rotation gears A 1B 1-N48008 2
  A 1B 1-N48032 1
Worm Screw and gear A 1C55-5N32 1
  A 1B 6-N32030 1
Sprocket gear A 6B 8-1932 2
Ladder Chain A 6B 8-19 1