Mars is the fourth planet from the Sun in our Solar System. While it’s not our nearest neighbor (Venus takes that honor) or the brightest planet in the night sky (also Venus), it is perhaps the planet that most inspires our imagination. Whether as home to “little green men” or as a future outpost for life from Earth, the planet figures heavily into science fiction books and movies. You know the fiction, now here are some facts about the “Red Planet”:
- Mars is a terrestrial planet, meaning it has a rocky surface. It is one of four terrestrial planets in our Solar System, along with Venus, Earth, and Mercury.
- Mars is about 4,220 miles in diameter, approximately half that of the Earth, and has about 11% of the Earth’s mass. Its surface gravitational pull is only about 38% that of the Earth.
- It takes Mars 687 Earth days to orbit the Sun, and just a little over one Earth day — 24 hours and 39 minutes — to rotate once on its axis.
- The surface of Mars bears similarities to both the Earth and our Moon. It is pocked with many craters, like the Moon, but also features live volcanoes, valleys, deserts, and polar ice caps, like Earth.
- Mars has two small and irregularly shaped moons, Phobos and Deimos.
- Mars is named after the Roman god of war, known as Ares to the Greeks. The planet’s two moons Phobos and Deimos are named after Ares’ children and attendants. Their names mean “fear” and “dread.”
- The surface temperature on Mars drops as low as about -225° F at the poles during winters. Its highest temperatures rise to about 90 ºF during summer.
- Because of the low surface gravity on Mars, it has only a very thin atmosphere. The planet’s atmosphere is made up of 95% carbon dioxide, 3% nitrogen, and 1.6% argon, with traces of oxygen, water, and methane.
- The thin atmosphere on Mars does not allow it to retain liquid water on its surface. Water, in the form of ice, can be found at the planet’s polar ice caps, and elsewhere. Recent exploration of Mars shows evidence of riverbeds and other signs that the planet may have once featured bodies of water that have since evaporated into space.
- Traditionally called “the Red Planet,” Mars often appears yellow, orange, or reddish to the naked eye. This red color is created by dust in the planet’s atmosphere. As Mars orbits the Sun, its brilliance varies more than any other planet in the night sky. It occasionally surpasses Jupiter as the third brightest object in the night sky, after the Moon and Venus.