Astronomy Picture of the Day

Explanation: As the Mars Global Surveyor spacecraft maneuvers toward its final mapping orbit, its cameras have been producing some sharp views of Mars. At a resolution of better than 30 feet per pixel, this image of a portion of the immense canyon, Valles Marineris, highlights the sheer mountain cliffs over 3200 feet tall near the canyon walls. The striking and extensive layering clearly apparent in the triangular mountain face was totally unanticipated. This exciting new result challenges common theories about the surface of Mars and argues that a complex early geological history is responsible for the current Martian landscape.