I love this photograph of a crater on Mars with water ice in it.
These images, taken by the High Resolution Stereo Camera (HRSC) on board ESA's Mars Express spacecraft, show a patch of water ice sitting on the floor of an unnamed crater near the Martian north pole.The crater is 35 kilometres wide and has a maximum depth of approximately 2 kilometres beneath the crater rim. The circular patch of bright material located at the centre of the crater is residual water ice.