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"
Infrared Mars
03/03/1999
Was Mars wetter and more Earth-like in its distant past? This false-color composite image of Mars is part of the mounting evidence that liquid water once did play a significant role in Martian surface geology. Constructed from infrared imaging data obtained by the Hubble Space Telescope in July 1997, the north polar cap is near the top of the picture and the large reddish region indicates potential water-bearing mineral deposits. Mars Pathfinder landed at the southern edge of this area, known as the Mare Acidalium, also finding evidence of water-worn conglomerate rocks. Large scale surface features in this region appear to have been sculpted by massive flooding in the early history of Mars.