This picture may be simple — monochromatic, a deep black background, and just a hunk fo rock to admire — but it's also stunningly beautiful. You're looking at Enceladus, the sixth-largest of the moons of Saturn, as pictured by Cassini.
Measuring 500km across, here's it illuminated by light reflected off Saturn. The simplicity of the picture is what makes it so charming: the deep black evokes a sense of endlessness that makes me realise just how much there is out there. Don't get lonely, Enceladus. [NASA]