The unmanned NASA/JPL space probe Voyager 1 makes its closest approach to the giant planet Jupiter, a little over 200,000 miles away. While Voyager’s higher-resolution cameras trump any of the Pioneer images of Jupiter, the real revelation proves to be Jupiter’s four largest moons, revealing a smooth-but-cracked icy surface on Europa, craters on Ganymede and Callisto, and the colorful mountains of Io, whose biggest secret goes undiscovered until a few days after Voyager 1’s closest flyby.
