Mars is often called the Red Planet, because its soil and dust contain iron minerals that have rusted. That gives much of the surface a reddish-orange color. It has mountains, the largest known volcano is Olympus Mons. It has Canyons Valles Marieris is a canyon system much larger than the Grand Canyon. It has Dry riverbeds, that show that water likely flowed on Mars long ago. It has Polar I’ve caps made of water ice and frozen carbon dioxide. Today, Mars does not have rivers or oceans on the surface. It is too cold and its atmosphere is too thin for liquid water to stay there for long. But the surface gives strong evidence that Mars was once wetter than it is now. It has very little oxygen, the atmosphere is mostly carbon dioxide, not breathable air. Earths air is 21% oxygen while Mars is only about 0.13%. So, we could not breathe there.