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"
Colorful Water Clouds Over Mars
17/04/2001
One place where water can be found on Mars is in clouds. In the above picture colorful water clouds are visible just after sunrise in and around a maze of canyons known as Noctis Labyrinthus (the labyrinth of the night). Scientists don't yet know, however, why these clouds formed, and why some stick to the canyons. One exciting possibility is that water sometimes condenses in shaded regions of the canyons, only to evaporate into clouds when exposed to the morning Sun. Water in any form on the Martian surface might be important to sustaining life and possible future human exploration. Viking Orbiter 1, which visited Mars in 1976, took the above picture. The region shown is about 100 kilometers across.