This is an image of Europa, one of the four largest moons of Jupiter. Europa was discovered in 1610 by Galileo, along with Jupiter's three other largest moons - Io, Ganymede, and Callisto. This image was taken by the Galileo spacecraft, which was named for the famous astronomer. The surface of Europa is ice, and the features observed in this (false-color) image are believed to be cracks in the surface ice, which many scientists believe may cover a liquid ocean. This is very exciting, because scientists believe that it may be possible that Europa's subsurface ocean may once - or even may still - harbor life.