Astronomy Picture of the Day

Explanation: This dramatic perspective view looks south-east along the wall of a large eroded impact crater on Solis Planum, bordering the mountainous Thaumasia region of Mars. Stretching for about 50 kilometres into the scene, the crater wall is around 800 metres high. Located just south and west of the Red Planet's grand Valles Marineris, this area features mountains and fault lines that are seen as evidence of surface plate motions or plate tectonics. The process of plate tectonics has long been shaping the surface of planet Earth but is thought to have been only briefly active on Mars. The image was constructed using colour image data from the High Resolution Stereo Camera onboard ESA's Mars Express spacecraft.