Mars
Mars is the fourth planet from the Sun and the seventh largest in the Solar System. A cold, dusty desert world with a thin atmosphere (mostly CO₂), the planet features extinct volcanoes, deep canyons, polar ice caps, and seasons. Mars has two small moons (Phobos and Deimos), a day just over 24 hours long, and a year lasting about 687 Earth days. It is a prime focus of robotic exploration and studies about past water and habitability.
Source: science.nasa.gov
APODs including "Mars"
Layers of the Martian South Polar Cap
25/04/2000
The South Pole of Mars is stranger than was previously thought. Pictured above are unexpectedly complex layers photographed recently by the Mars Global Surveyor spacecraft currently orbiting Mars. The layers probably include carbon dioxide ice, water ice, rock and dust. The intricate structures might indicate erosion patterns that hold clues to the history of the Martian climate over the past 100 million years. The above image covers a region five kilometers across, resolving details as small as 25 meters across.