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LOCATION: Mars is the fourth planet from the Sun, orbiting at a mean distance of 227.9 million kilometres, about half as much again as the distance between the Sun and Earth.
DIAMETER: 6,794kms. By comparison, Earth's diameter is 12,756kms
MARTIAN DAY: 24 hours 37 minutes and 22 seconds
MARTIAN YEAR: 669 martian days (687 Earth days)
TEMPERATURE: Average - 55 C (- 67 F). Minimum: - 133 C (- 207.4 F), at the poles in winter. Maximum temperature: 27 C (80.6 F) in summer on equator
ATMOSPHERE: Composition 95.32 percent carbon dioxide (CO2), 2.7 percent nitrogen, 1.6 percent argon, 0.13 percent 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 10kms high and 4,000kms across; Valles Marineris, a canyon 4,000kms long and up to seven kms deep.
MOONS: Phobos, diameter 22 kms (13.75 miles), orbit 5,981 km (3,738 miles) from surface; Deimos, diameter 12 kms (eight miles), orbit 20,062 kms (12,538 miles) from surface. -AFP
