6 January 2004

The north polar cap of Mars is nearly surrounded by fields of dark, windblown sand dunes. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example located near 73.5°N, 75.0°W. The orientation of these dunes indicate that the dominant winds--particularly those that occur during storms--come from the upper left (northwest). The picture covers an area about 3 km (1.9 mi) across, and is illuminated by sunlight from the lower left.