This picture has to be one of the best sunset pictures ever taken. It shows a sunset on Mars.
This image was taken on May 19, 2005, by NASA's Mars Exploration Rover Spirit at the edge of Gusev Crater. Click the image to enlarge it to high-resolution. The included picture is large enough to use as a desktop on most monitors.
Image Courtesy of NASA/JPL/Texas A&M/Cornell.