MARS      Fourth planet from the Sun

          Mean distance from Sun:    1.52 AU = 228,000,000 KM

          Diameter:                  6800 KM

          Mass:                      0.53 Earths

          Density:                   3.9 grams / cubic centimeter

          Surface temperature:       72 F to -271 F

          Orbital period:            686 days
        
          Mars appears reddish in our sky, even to the naked eye. This is 
          caused by the rich content of rust (iron oxide) in the top 
          soil.  In the Martian springtime the surface of the planet 
          changes color due to seasonal winds covering and uncovering 
          darker surfaces of reddish dust.  Mars has two small moons -
          Phobos is the larger and zips around Mars in only 7 1/2 hours.  
          Deimos, the smaller moon, takes 30 hours to orbit.