Astronomy Picture of the Day

Explanation: Steep cliffs drop into the rugged terrain of Melas Chasma in this stunning view from the Mars Express spacecraft orbiting the Red Planet. At a scale of 16 metres per pixel, the image data from the orbiter's High Resolution Stereo Camera offers evidence that volcanic activity, water, wind erosion and marsquakes may all have shaped the region. Melas Chasma lies along the central southern edge of the large Valles Marineris, the grand canyon of Mars. While the Valles Marineris is itself over 4,000 kilometres long and up to 10 kilometres deep, the region pictured spans about 70 kilometres. The floor of Melas Chasma seen here is several kilometres below the surrounding plateau.