This view from NASA's Cassini spacecraft looks toward Saturn's icy moon Dione, with giant Saturn and its rings in the background, just prior to the mission's final close approach to the moon on August 17, 2015. At lower right is the large, multi-ringed impact basin named Evander, which is about 220 miles (350 kilometers) wide. The canyons of Padua Chasma, features that form part of Dione's bright, wispy terrain, reach into the darkness at left. Image credit: NASA
This global view of Jupiter's moon, Io, was obtained during the tenth orbit of Jupiter by NASA's Galileo spacecraft on 19 September 1997 at a range of more than 500,000 km (310,000 miles). Io (which is slightly larger than Earth's moon) is the most volcanically active body in the solar system. Colors are enhanced.