Mars surface dunes
© NASA/JPL-Caltech/ASUImage shows Mars' northern polar cap
A sea of dark dunes, sculpted by the wind into long lines, surrounds Mars' northern polar cap and covers an area as big as Texas. In this false-color image, areas with cooler temperatures are recorded in bluer tints, while warmer features are depicted in yellows and oranges. Thus, the dark, sun-warmed dunes glow with a golden color. This image covers an area 19 miles (30 kilometers) wide.

This scene combines images taken during the period from December 2002 to November 2004 by the Thermal Emission Imaging System instrument on the Mars Odyssey orbiter. It is part of a special set of images marking the 20th anniversary of Odyssey, the longest-working Mars spacecraft in history. The pictured location on Mars is 80.3 degrees north latitude, 172.1 degrees east longitude.