Mars’ atmosphere: Facts about the composition and climate

Mars’ atmosphere is over 100 times thinner than Earth’s and is primarily composed of carbon dioxide, nitrogen and argon gases. Oxygized dust particles kicked up from the Martian surface fill the atmosphere turning Mars’ skies a rusty tan color, according to NASA

Water exists on Mars but the atmosphere is too thin for it to last long on the surface in a liquid state. Instead, water on Mars is found below the surface of the polar regions as water-ice and also as seasonal briny water flows down hillsides and crater walls.