Scientists believe conditions may be right for life, under Europa's icy crust.
Europa, the icy "cue ball" moon of Jupiter, has a relatively smooth crust of ice over a watery interior ocean. Cracks in the crust are due to the tidal forces of Jupiter's mighty gravity. Scientists believe that Europa has the right conditions for some form of life to exist there today.
FULL STORY: What Would It Be Like to Live on Europa?
Europa has a thin oxygen atmosphere, but it is far too tenuous for humans to breathe. From the surface of Europa, Jupiter appears 24 times larger than the moon appears in our sky. Europa's magnetic field shields its surface from Jupiter's deadly radiation.