Mars is named for the Roman god of war. That’s because the planet’s red color reminded Roman skywatchers of blood. But ancient Rome isn’t the only culture that named the planet for its vivid color. In ancient Egypt, it was “the Red One.” In China, it was “the fire star.” And in Arabia, it was simply “fire.”
Mars looks redder from afar than from up close. Pictures from orbiters and landers show that most of the surface has a more subtle hue: butterscotch. But big patches of it show other colors: gold, brown, tan, and even green. The color varies depending on the minerals at the surface.
And even in the red areas — make that butterscotch — the color is only skin deep. The color comes from a layer of powdery dust that coats much of the surface. Across most of the planet, it’s only a few millimeters thick. And even at its deepest, it’s only a few feet thick.
The dust consists of iron oxides — rust. On Earth, rust usually forms in the presence of water. On Mars, though, it may form from reactions with the atmosphere, or even from erosion by the winds. The winds blow the dust around, and suspend a lot of it in the atmosphere — making it look yellow or red as well. Beneath that veneer, the rock tends to be darker — chasing away the “red” in the Red Planet.
Look for Mars quite close to the Moon this evening. It looks like a fairly bright star. The glare of the Moon washes out its color — whatever it is.
Script by Damond Benningfield