This is an Orrery, which is a model of the solar system named after the Earl of Orrery. A small orrery was presented to Charles Boyle, the fourth Earl of Orrery, in 1704 and the name Orrery stuck. This is our version and, as far as we know, it is the only true-to-scale, true-to-position Orrery in the world. Our scale is 20 billion to one, which means the real sun is 20 billion times bigger than ours.