The top of the clock features a model of the earth, which both rotates around its own axis and revolves around a sun made of brass. A gear train allows the moon to rotate the earth -- always presenting the same face to earth-bound observers. (I know! Think about it.) While it might not be to scale, the various revolutions are in accord with real time.
Among the exotic materials in this astrolabium are cherry wood, crystal, abalone, green agate, jade, and mother of pearl. I'll take two, please.
Here is a link for more information about The Astrolabium Clock.