Astronomy Picture of the Day

Explanation: First imaged by the Mariner 9 spacecraft, Valles Marineris, the grand canyon of Mars, is a system of enormous depressions or chasmas that stretch some 4,000 kilometres along the Martian equator. Looking north over the canyon's central regions, dark Melas Chasma lies in the foreground of this spectacular perspective view. Behind it are Candor Chasma and the steep walls of Ophir Chasma near the horizon. Faulting, surface collapse and landslides are seen to be part of the complex geologic history of these dramatic features, with layered deposits also found within the canyon system. Recorded in 2004, the image represents data from the High Resolution Stereo Camera (HRSC) on board ESA's Mars Express spacecraft. Melas, Candor and Ophir are about 200 kilometres wide and 5 to 7 kilometres deep.