Jupiter And Family . ... Credit Copyright: Galileo Project , Voyager Project , JPL , NASA . Explanation: This composite image features classic portraits of members of one of the Solar System's most prominent families - Jupiter and its four large "Galilean" moons. Starting from the top the moons are Io , Europa , Ganymede , and Callisto . ... The smallest of the lot, Europa, is the size of Earth's moon while Ganymede is the largest moon in the Solar System. ... NASA Official: Jay Norris. ...