There are several ways to group the moons of the Solar
System. Some groupings are based on the sequence of the
moons in their orbits around their parent planets; others
are based on the sizes or compositions of the moons. For example,
a few moons are predominantly rocky objects, some
are mostly ices, and most appear to be mixtures of ice and
rock. In this chapter we will group moons by the amount
and history of the moons’ geological activity.