The Realistic Size of an Orrery

I'll bet you don't know what an orrery is! It is one of those things you see
in museums that model the solar system. The sun and the planets are made out
of various size balls held on wires, and they circle around like the hands
of a clock.

Orreries are hopelessly out of scale. In reality, if the sun were three feet
in diameter, the earth would be the size of a pea. The pea would be circling
the three-foot sun on a wire 100 feet long. This whole thing, with the
pea-size earth, and with all the other planets including Pluto would be over
ninety miles in diameter.

- from www.intelligence-builder.com