Perfect examples of icy moons are 3 of the Galilean satellites, Europa, Ganymede, and Callisto. Except maybe for Europa and Triton, these moons have no atmosphere. But the surfaces of these moons, especially Ganymede, show that in their history, something may have happened inside which changed the way the surface of the moon looks today. Activity in the interior could also provide an environment suitable for life. |

