NASA - National Aeronautics and Space Administration

Jupiter and its four planet-size moons

Jupiter and its four planet-size moons, called the Galilean satellites, were photographed in early March by Voyager 1 and assembled into this collage. They are not to scale but are in their relative positions. Startling new discoveries on the Galilean moons and the planet Jupiter made by Voyager 1 have been factored into a new mission design for Voyager 2. Voyager 2 will fly past Jupiter on July 9.