Mars: 3-D Dunes.

Get out your red/blue glasses and treat yourself to this dramatic 3-D view of sand dunes on Mars ! The field of undulating dunes is found in Nili Patera, a volcanic depression in central Syrtis Major , the most prominent dark feature on the Red Planet . Two different images from the orbiting Mars Global Surveyor spacecraft were combined to make this stereo picture , one taken in March 1999 and the other recorded in April 2001. Sculpted by winds like the sand dunes of Earth , these particular Martian dunes show no change in shape over the time separating the two images, a period equivalent to about one Martian year . This cropped version of the 3-D picture spans an area around 2 kilometers across. Walking, you might cover that distance in about 20 minutes.