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 air. But the surfaces of these moons, especially Ganymede, show proof that in their history, something may have happened inside which changed the way the moon looks today. Activity inside the moon could also provide an environment in which life could exist. |

