Moons: 2 95% carbon dioxide, 3% nitrogen, 1.6% argon basaltic rock and altered materials
Mars is the fourth planet from the Sun. Mars is a small rocky body once thought to be very Earth-like. Like the other terrestrial planets, its surface has been changed by volcanism, impacts from other bodies, movements of its crust, and atmospheric effects such as dust storms. It has polar ice caps that grow and recede with the change of seasons; areas of layered soils near the Martian poles suggest that the planet's climate has changed more than once. Periodically, great dust storms engulf the entire planet. The effects of these storms are dramatic, including giant dunes, wind streaks, and wind-carved features.