Every Hidden Ocean In Our Solar System Explained In 15 Minutes

Europa The smoothest large object in the solar system, and that smoothness is the first clue to what lies beneath it. One of Jupiter's four large moons, slightly smaller than Earth's own Moon, its surface is a shell of water ice crossed by long reddish-brown streaks. There are almost no craters. On a world that has been bombarded for billions of years like everything else, the absence of craters means the surface is young and constantly being renewed. Something is erasing the record.