Europa is one of Jupiter’s largest moons and is known primarily for its ice-covered surface and the potential for a subsurface ocean beneath the ice. It is the smallest of the four Galilean moons discovered by Galileo Galilei in 1610. Europa’s surface is characterized by a smooth, bright appearance, crisscrossed by a complex pattern of streaks and ridges, which are likely caused by the movement of ice over a liquid interior.