Mars has a diameter 6,800 kilometres and is about a tenth the mass of the Earth. Mars has a thin atmosphere rich in carbon dioxide. The dry rocky surface is covered with orange sand and is constantly swirled about by driving winds. The sand makes the planet look red when seen in the night sky. Mars has two moons, Phobos and Deimos.

Mars spins on its axis at about the same rate as the Earth and orbits 240 million kilometres from the Sun. Mars appears to have strange features on its surface, called canals, making people wonder if there has ever been life on the planet. Some 'canals' are, in fact, rift valleys, signs of the way the surface formed. Others may well be dried up canyons which were cut by rivers several hundred million years ago. There is no liquid water on Mars today, only ice.

Volcanoes grow to spectacular heights on Mars: the largest yet spotted – called Mount Olympus – is 24 kilometres high and 500 kilometres across its base, three times the height and four times the breadth of the largest volcano on Earth. Mars has polar ice caps like on Earth, but on Mars they grow and shrink dramatically each year as the seasons change.

You can tell when Mars is in the night sky. It shines with a steady red light. There are plans for people to visit Mars. These trips may be made in your life time.