Jupiter and its four planet-sized moons, called the Galileon satellites, were photographed in early March 1979 by Voyager 1 and asembled into this collage. They are not to scale but are in their relative positiions. Reddish Io (upper left) is nearest Jupiter, Europa is in the centre of the image and Ganymede and Callisto are to the lower right of the image. Nine other much smaller satellites circle Jupiter, one inside Io's orbit and the other millions of miles from the planet. Not visible is Jupiter's faint ring of particles, seen for the first time by Voyager 1.
© National Aeronautics & Space Administration / Science & Society