Mars is the fourth planet in order of distance from the Sun and seventh in order of decrease size and mass. It orbits the Sun once in 687 Earth days and spins on its axis once every 24 hours and 37 minutes.

Because of its blood-red color, Mars, has often been associated with gods of war. It is named for the Roman god of war; The Greeks called it Ares for their god of battle; the planet's two satellites, Phobos (Fear) and Deimos (Terror), were named for two of the sons of Ares and Aphrodite.

Mars is a small planet. Mars has four times less surface area than the Earth, and its gravity is reduced by nearly a factor of 3. The gravitational escape velocity is 5.022 km/sec as opposed to the Earth's 8km/sec escape velocity..

The average recorded temperature on Mars is -63C (-81F) with a maximum temperature of 20C (68F) and a minimum of -140C (-220F).

Mars has a gravity of 0.38g, earth has 1g. At 0.38g human beings probably live with no side effect like bone shrinking. A Mars' day, unlike all other planets' day, is comparable in length with earths' day. At the equator, the day is 24.5 hours long, on Earth, the day is about 24 hours long.

The martian atmosphere is only 7mbars thick, which is not very much compared to Earths' 1000mbar atmosphere. But this atmosphere is thick enough to prevent the deadly solar storms from reaching the surface of the planet. Because Mars' gravity is about 1/3 as strong as Earth's, the 7mbar atmosphere would be a 21mbar atmosphere on Earth. The atmosphere is mainly ( to 95% ) made of carbon dioxide ( CO2). The rest is oxygen ( O2 ), nitrogen ( N2), water vapour ( H2O ) and noble gases ( He, Ne, Ar...).

But Mars also has a very interesting geology which has a lot of touristical value. It has the largest canyon system in the solar system ( Valles Marineris) and also the by far highest and largest volcano in the solar system ( Olympus Mons which is 26 km high ). It also has beautiful and enormous craters, which do not exist on Earth. Interesting to know is that the northern hemisphere is much lower that the southern hemisphere. This could have been provoked by an enormous meteorite impact. Mars also has two small asteroid-like moons that can be seen from the surface.

What is most interesting about Mars is that it is possible to terraform it with today's technologies and a modest budget. It is the only planet we know of where this is possible.