NASA Mars Picture of the Day: Frosty Dunes

Today, the MOC Team celebrates the 45th anniversary of the first human flight into space, that of Yuri Gagarin on 12 April 1961, and the 25th anniversary of the first NASA Space Shuttle flight on 12 April 1981, by briefly pondering the wonders of our Solar System and the opportunities of the age in which we live.
Although humans have not ventured to the Moon in more than 30 years, and
have not yet gone to Mars, we can all go there through the eyes of our robotic
explorers.

Mars, perhaps the most Earth-like (yet so very different!) planet
in our star’s system, is tilted on its axis by about 25°—not
all that different than Earth’s ~23.5°. Thus, Mars, like Earth,
experiences a changing of seasons as the planet revolves around the
Sun. At high latitudes in each hemisphere during autumn and winter,
carbon dioxide frost accumulates on the surface.

This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows
dunes covered and delineated by seasonal frost in the north polar
region of Mars. The winds responsible for the formation of these
dunes blew primarily from the northwest (upper left), with
additional influences from the north and northeast. During the
late spring and summer seasons, these dunes would look much darker
than their surroundings, but in this late winter image, the dunes
and the plains on which they occur are all covered with
carbon dioxide frost.