Astronomy Picture of the Day . ... The smallest of Jupiter 's Galilean Moons (which include Io , Ganymede , and Callisto ), Europa's deep interior is composed of mostly of silicate rock . ... The movie shows Europa during a complete rotation, which corresponds to a complete revolution around Jupiter since Europa always keeps the same face toward the giant planet. ... Publications with keywords: Europa - rotation - Jupiter's Moons . Publications with words: Europa - rotation - Jupiter's Moons . ...