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"
Opportunity's Horizon
04/02/2004
Remarkably, the Opportunity Mars rover lies in a small martian impact crater about 3 meters deep and 22 meters wide. For 360 degrees, Opportunity's horizon stretches to the right in this new color mosaic image from the rover's panoramic camera. Notable in this view of the generally dark, smooth terrain are surface imprints left by the lander's airbags and an outcropping of light-colored, layered rock about 8 meters away toward the northwest. Though they look imposing, the rocks in the tantalizing outcrop are only a few centimeters high and will be dwarfed by the cart-sized rover itself during future close-up investigations. Opportunity has now rolled off its lander and, along with the restored Spirit rover, is directly exploring the martian surface.