Mars: A factfile
2003-08-27 07:39
Orbit: 227.9 million kilometres mean distance from the Sun, about half as much again as the distance between the Sun and Earth.
Diameter: 6 794 kms. By comparison, Earth's diameter is 12 756 kms.
Martian Day: 24 hours 37 minutes and 22 seconds
Martian Year: 669 martian days (687 Earth days)
Temperature: Average - 55 C . Minimum: - 133 C, at the poles in winter. Maximum temperature: 27 C in summer on equator
Atmosphere: Composition 95.32% carbon dioxide (CO2), 2.7% nitrogen, 1.6% argon, 0.13% oxygen. Pressure at surface is less than 1/100th Earth's atmospheric pressure.
Landscape: Rocky, dusty and dry, although some scientists speculate water lurks close to surface. Northern hemisphere is smooth and flat, southern hemisphere is deeply cratered, rugged highlands.
North pole has a large, permanent cap of what is believed to be mainly water ice. South pole has a small cap, which may be frozen carbon dioxide (CO2) and almost disappears during the martian summer.
Major features: Olympus Mons, at 26 000 metres, the highest known volcano in the Solar System; Tharsis Dome, a mysterious bulge 10 kms high and 4 000 kms across; Valles Marineris, a canyon 4 000 kms long and up to seven kms deep.
Moons: Phobos, diameter 22 kms, orbit 5 981 km from surface; Deimos, diameter 12 kms, orbit 20 062 kms from surface.