The Red Planet: Key facts and figures

August will be an unforgettable month for amateur astronomers as they turn their gaze on Mars, now at its closest to Earth since Neanderthals walked our planet.

    US space agency's robot probe will explore the surface in 2004

    Here are the main facts and figures about our red-orange neighbour:

    Orbit: 227.9 million kilometres mean distance from the Sun, about half as much again as the distance between the Sun and Earth. 

    Diameter: 6794km. By comparison, Earth's diameter is 12,756km, so Mars about half the size of our planet. 

    Martian day: 24 hours 37 minutes and 22 seconds. 

    Martian year: 669 martian days (687 Earth days).  

    Temperature: Mars is much colder than Earth. Average:
    -55C (-67F). Minimum: -133C (-207.4F), at the poles in winter. Maximum temperature: 27C (80.6F) in summer on equator.  

    Atmosphere: Unbreathable for us humans. 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 10km high and 4000km across; Valles Marineris, a canyon 4000km long and up to seven kilometres deep. 

    Moons: Phobos, diameter 22km, orbit 5981km from surface; Deimos, diameter 12km, orbit 20,062km from surface. 

    SOURCE: AFP


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