Date: 15 Dec 2010
Wind shadow and real shadow combine with an impact crater to produce a "comet." Winds blowing over the crater's rim have scoured the ground behind the crater free of light-colored dust, leaving exposed a relatively bare lava flow. The crater spans a width of about 3 kilometers (2 miles).
Humanity is a very visual species. We rely on our eyes to tell us what is going on in the world around us. Put any image in front of a person and that person will examine the picture looking for anything familiar. Even if the examiner has no idea what he/she is looking at in a picture, he/she will still be able to make a statement about the picture, usually preceded by the words "it looks like..." The image above is part of the surface of Mars, but is presented for its artistic value rather than its scientific value. When first viewed, this image solicited a statement that "it looks like..." something seen in everyday life.
Credit: NASA/JPL/Arizona State University