Mars is the fourth planet from the Sun and the seventh largest:

        orbit:    227,940,000 km (1.52 AU) from Sun
        diameter: 6,794 km
 Mars (Greek: Ares) is the god of War. The planet probably got this name due to its red color; Mars is sometimes referred to as the Red Planet.
The name of the month March derives from Mars.  Mars has been known since prehistoric times.
 
 

It is still a favorite of science fiction writers as the most favorable place in the Solar System (other than Earth!) for human habitation. There is very clear evidence of erosion in many places on Mars including large floods and small river systems. At some time in the past there was clearly water on the surface. There may have been large lakes or even oceans.
    Mars has two tiny satellites which orbit very close to the surface. These moons are called Phobos and Deimos.