Jupiter is surrounded by a solar system in miniature of 63 known moons.

Most (59) are tiny, irregular bodies that are a combination of captured

asteroids and comets. The 4 largest are the giant Galilean Moons: Io,

Europa, Ganymede, and Callisto. Each is a fascinating world of its own,

with a unique history and properties: volcanically active Io, icy Europa

which may hide an ocean of liquid water beneath the surface, the grooved

terrain of Ganymede, and frozen dirty Callisto with the most ancient

surface of the four. Recorded 2006 Nov 20 in 100 Stillman Hall on the

Columbus campus of The Ohio State University.