NASA / JPL-Caltech / processed by Emily Lakdawalla
Enceladus and Mimas nightsides
As Cassini approached for its close flyby of Enceladus on December 20, 2010, it caught Mimas passing through the field of view. The Sun was nearly in front of Cassini so both moons are lit only as very skinny crescents; the lighting highlights Enceladus' plumes, and shines off of tiny particles in the E ring, which provides a lighter backdrop to the dark night sides of both moons. Mimas and Enceladus are actually very similar in size, but Enceladus was much closer to Cassini when the photo was taken.