Jupiter, the largest planet in the solar system, has 16 known moons altogether. Four of them are large and easily visible if you look at Jupiter with binoculars or a small telescope. You can follow the motion of these moons - Io, Europa, Ganymede and Callisto - as they orbit around Jupiter like a miniature solar system. The quickest, Io, dashes round Jupiter in just under two days. The furthest, Callisto, takes over 16 days.
