20 Big Mysteries We Still Haven’t Solved in Space

Jupiter’s moon Europa has a cracked ice crust, resembling a shattered stained-glass window. Magnetic readings from spacecraft indicate that a deep, warm ocean lies beneath the thick ice, warmed by Jupiter’s powerful gravity. The concealed sea may contain twice as much liquid water as all of Earth’s oceans combined. Europa draws strong scientific interest because it ranks high among places where living microbes might be found.