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The Galilean moons. By S ierra Lewis. The Galilean moons. Io Europa Ganymede Callisto. Lo.
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The Galilean moons By Sierra Lewis
The Galilean moons • Io • Europa • Ganymede • Callisto
Lo • The Voyager spacecraft took the first close-up images of Io more than 300 years after the moon's discovery. The images showed a surface with no signs of craters from past impacts. What we saw instead was a surface almost entirely covered with large volcanoes. Cameras on Voyager actually captured volcanic eruptions in progress. The frequency of these sulfuric eruptions has filled in almost all of the impact craters and left Io with one of the youngest looking surfaces in the solar system.
Europa • Europa's surface and crust are made almost entirely of water ice, and its bizarre, fractured appearance is proof enough that tidal heating has acted there. The icy surface is nearly devoid of impact craters and may be only a few million years old.