383787 01: The entire body of Moon-sized Io, as it casts a black shadow, is captured here alongside the planet Jupiter in this picture taken by NASA's Cassini spacecraft, December 3, 2000. Jupiter's other moon, Ganymede is larger than the planets Mercury and Pluto and Saturn's largest moon, Titan. Both Ganymede and Titan have greater surface area than the entire Eurasian continent on our planet. Cassini was 26.5 million kilometers (16.5 million miles) from Ganymede when this image was taken. The smallest visible features are about 160 kilometers (about 100 miles) across. (Photo courtesy of NASA/Newsmakers)
