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"
Olympus Mons Volcano on Mars
29/05/2000
Scroll right to virtually climb the largest volcano in the Solar System. Olympus Mons on Mars measures three times higher than Earth's highest mountain, and has a volume over fifty times greater than Earth's largest volcano. The caldera at the top is over 70 kilometers wide. The low gravity and relatively static surface crust on Mars allows structures as large as Olympus Mons to form. Surrounding the volcano is a cliff that ranges up to 10 kilometers high. This black & white image is one of over 20,000 just-released images taken by the robot spacecraft Mars Global Surveyor that continues to orbit Mars.