This is one of my current favourite images taken by the spacecraft Cassini. It's a magnificent panoroma with Saturn's largest moon, Titan, in the foreground, with the icy moon Dione behind it. Titan's diameter is about 3000 kilometres; Dione's is about 1000 kilometers, but it appears much smaller here because it's further away. If you click to embiggen the image you'll see that Titan is haloed by the upper fringe of its frigid atmosphere of nitrogen leavened with methane and a smoggy mix of hydrocarbons. Saturn and the ring system are in the background, with the shadow of the ring system thrown across Saturn's southern hemisphere - the sun is beyond the upper left-hand corner of the image. You can find a high-resolution version of the image here.
The image was taken a year ago, December 22 2011. After a seven year voyage, with flybys past Venus, Earth, and Jupiter, Cassini entered orbit around Saturn on July 1 2004. The Huygens probe that piggybacked on Cassini landed on Titan's surface soon afterwards, and Cassini has been doing science and taking fabulous images ever since. As I've said many times, much of the inspiration for The Quiet War and Gardens of the Sun comes from images taken by a plutonium-powered robot swinging in ever-changing orbits amongst the moons and rings of the second-biggest gas giant in the solar system.