Seven times smaller than Earth and 10 times less massive, Mars is a comparatively small planet. Encircled by 2 small satellites, Phobos and Deimos, it is a solid sphere with a desert landscape tinged red by iron oxide.

With a gravitational force just one-third of that on Earth, Mars has only been able to retain a very thin, tenuous atmosphere consisting of 95% carbon dioxide. Atmospheric pressure is highly variable and 170 times weaker than on Earth.
With little heat from the Sun and no significant greenhouse effect, temperatures at the equator vary between –100°C and 0°C.

Most of the changes to Mars’ surface are caused by the winds that sweep across its dry landscape, raising clouds of ochre dust and turning the atmosphere a reddish brown. Violent storms periodically hurl these dust clouds 50 kilometres into the air, totally blocking out the sky.

^{Last updated: May 2003}