Exploratour - Evolution of the Solar System
Two other examples of neighboring bodies which have had a different history are Jupiter's moons Ganymede and Callisto. Ganymede seems to have a large core with an icy middle and crustal layer on top. Callisto, the neighboring moon, seems to be completely the same from the center to the surface. This means that Ganymede separated into layers early in its history while Callisto did not.
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