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
01/10/2001

A dust storm on Mars can involve nearly the entire planet. As spring descended on the southern hemisphere of the red planet this June and July, a global dust storm raged. Pictured above is the storm on July 8 as it spread up from the south, oriented on the lower right. The image was captured by the robot Mars Global Surveyor spacecraft which continues to orbit the red planet. A smaller dust storm is visible in the north to the left of the dark giant volcano Ascraeus Mons. Far-reaching dust storms also occur on planet Earth.