Why is the planet Mars red?

In the sky, the planet Mars appears as a red star. A color that she owes to her soil composed mainly of iron oxide.

Mars is one of five planets visible to the naked eye. Thus, in ancient times already, the Romans had found in the sky the red color so special of the fourth planet of the Solar System. Translating his color as the result of blood spilled on huge battlefields, they chose to give him the name of their god of war.

A red planet like rust

Today, we know that no bloody war has taken place on the floor of the Red Planet. If Mars appears to us so tinted, it is because its soil is rather largely composed of iron oxide: rust, so to speak.

Indeed, more than 3 billion years ago, when it was not red at all, the planet would have experienced a solar event having literally blown its atmosphere. Particularly tenuous, it then slowly oxidized a Martian soil rich in iron.