Mars /ˈmɑːrz/ is the fourth planet from the Sun in the Solar System. The planet is named after Mars, the Roman god of war. It is also referred to as the "Red Planet" because of its reddish appearance. Mars has two tiny natural moons, Phobos and Deimos, discovered in 1877 by Asaph Hall, which orbit very close to the planet and are thought to be captured asteroids.
Mars is a terrestrial planet with a thin atmosphere, having surface features reminiscent both of the impact craters of the Moon and the volcanoes, valleys, deserts and polar ice caps of Earth. It is the site of Olympus Mons, the highest known mountain in the Solar System, and of Valles Marineris, the largest canyon. Mars has been the focus of dozens of missions, the most recent being the Mars Scout Program's Phoenix probe...