Why does Mars appear red?

Another name for Mars is the Red Planet, and if you’ve ever seen it in the sky when the planet is bright and close to Earth, it appears like a bright red star. In Roman mythology, Mars was the god of war, so… think blood.

Even photos from spacecraft show that it’s a rusty red color. The hue comes from the fact that the surface is *actually* rusty, as in, it’s rich in iron oxide.

Iron left out in the rain and will get covered with rust as the oxygen in the air and water reacts with the iron in the metal to create a film of iron oxide.

Mars’ iron oxide would have formed a long time ago, when the planet had more liquid water. This rusty material was transported around the planet in dust clouds, covering everything in a layer of rust. In fact, there are dust storms on Mars today that can rise up and consume the entire planet, obscuring the entire surface from our view. That dust really gets around.

But if you look closely at the surface of Mars, you’ll see that it can actually be many different colours. Some regions appear bright orange, while others look more brown or even black. But if you average everything out, you get Mars’ familiar red colour.