Mars, as seen by the Hubble Space Telescope in 1999.
Mars is the fourth planet from the sun and the second smallest planet in the Solar System. The planet is named after the Roman god of war. The planet's surface contains iron oxide, giving the planet a reddish appearance. This is why Mars is nicknamed the "Red Planet."
Orbit and Rotation
Mars takes 687 days to orbit the sun. It takes 24 hours, 39 minutes, and 35 seconds to rotate once on its axis.
Mars, as seen from Viking 1 in 1980. Valles Marineris is in the center.
Mars's surface has canyons, mountains, volcanoes, and icy poles, much like Earth. But there is one huge difference: they're larger. Olympus Mons, the largest mountain and volcano in the Solar System, is 14 miles high and located on Mars. Valles Marineris, located on Mars, is one of the largest canyons in the Solar System. Mars may once had oceans, and possibly even life.
Mars's atmosphere is 95.32% carbon dioxide, 2.7% nitrogen, 1.6% argon, 0.13% oxygen, and 0.08% carbon monoxide, with traces of water vapor, nitric oxide, molecular hydrogen, neon, HDO, krypton, formaldehyde, xenon, hydrogen, and methane.
Mars's temperatures are related to Earth: -124 degrees to about 70 degrees Fahrenheit.
Mars has two moons, Deimos and Phobos.
Mars is probably the most explored planet other than our own. The red planet had its first flyby in 1965. Its first lander, Viking 1, came not long later. Mars has been explored by Spirit and Opportunity rovers in the past eight years. The new Curiosity rover is searching for traces of life on Mars.