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
23/08/2004

What would it be like to climb a hill and look out over Mars? That opportunity was afforded the Spirit rover earlier this month as it rolled to a high perch in the Columbia Hills. Peering out, the rolling robot spied the interior plains and distant rim of Gusev Crater, beyond an outcrop of rocks called Longhorn. Spirit continues to find evidence that many rock shapes have been altered by ancient water. Both Spirit and her sister robot Opportunity have completed their primary three-month mission but remain in good enough condition to continue to explore Mars.