This icy moon of Saturn also has subsurface deposits of liquid water or slush, a rocky core, and Saturn's gravity for heat. Active ice volcanoes could be circulating nutrients that life forms could use.
Life on Earth occupies some bizarre places – pools of pitch, deep-sea hydrothermal vents, and lightless lakes buried under glaciers. While scientists hunt for hospitable planets circling other stars, the solar system has a few candidates. Here are five.