This 'family portrait,' a composite of the Jovian system, includes
the edge of Jupiter with its Great Red Spot, and Jupiter's four
largest moons, known as the Galilean satellites. From top to bottom,
the moons shown are Io, Europa, Ganymede and Callisto.
(<a href="http://photojournal.jpl.nasa.gov/catalog/PIA00600">PIA00600</a>)