Parade of Moons
Saturn and close-ups of three moons: Dione, Helene and Tethys, all photographed during the past few days. The worlds are not shown to scale. Dione and Tethys are very similar, both made largely of water ice, and about a thousand kilometers across each. Helene, on the other hand, is only about 30 kilometers wide.
July 24, 2007
Riding with Robots:
