Europa

Also called �Jupiter II, � fourth largest satellite of the planet Jupiter. One of the four Galilean satellites, it was discovered by the Italian astronomer Galileo Galilei in 1610 and was named by the German astronomer Simon Marius after a figure in Greek mythology. Europa has a diameter of 3,138 km (1,946 miles), and it orbits Jupiter at a distance of approximately 670,900 km (416,900 miles). The satellite has a density of 3.03 grams