Mars Mars,is a planet in the solar system.I'ts named for the Roman god of war Ares.Mars is the fourth planet from the sun.Mars has two small heavily craterd moons,Phobos and deimos,astronomers think they are areastroid like objects captured by the planet very early in history.Phobos is about 13 miles across;Deimos,is only 7.5 miles.Mars not on a telescope, Mars is a reddish varying in brightness.At its closes approach to earth (34 million miles)after Venus,Mars is the brightest object in the night.Mars is best seen when it is opposite the sun in Earth's sky and cl