Mars has a very thin atmosphere with barely any oxygen (it is mostly carbon dioxide).Because there is an atmosphere, however thin it is , the sky does change carbon when the sun rises and sets. The dust in the Martin atmosphere make the Martin sunsets have a rather blue colour. Mar’s atmosphere , of course , is too thin to protect Mars from meteors, which is why the lower half of mars has so many craters. Mars is home to the highest known mountain in the solar system, Olympus mons. Olympus Mons is about 17 miles (or 27 kilometers) high. This is more than three times the height of Earth’s tallest mountain, Mount Everest. It is also home to valles Marineris , the third largest rift system (canyon) in the solar system 4,000 km long. Because Mars is the one of the closest planets to earth in the solar system, many have wondered if there is any kind of life on Mars. Today we know that the kind of life, if any , would be some simple bacteria type organism. Liquid water is necessary for life and metabolism , so if water was present on Mars , the changes of life evolving is improved. The viking orbits found evidence of possible river valleys in many.