Mars is called the Red Planet because its reddish colour is easily visible to the naked eye. It is red because its surface is a desert covered with sands made of compounds of oxygen and iron - similar to iron rust.

There is very little surface water on Mars and most of this is frozen in the polar caps.

Distance from Sun (million km): 227.9 57.9
Year (time to go round the Sun): 687 Earth days 88 Earth days
Day (time to revolve round axis): 24 hours 37 minutes
Diameter at equator (km): 6,794
Known moons: 2
Mass (Earth = 1): 0.11
Gravity at surface (Earth = 1): 0.38