Mars is often referred to as the “Red Planet” for obvious reasons. But what gives our neighboring planet this distinctive hue? While Earth is sometimes called the “blue marble” because it’s mostly covered by ocean and has a dense atmosphere that gives it a blue appearance, Mars is covered in lots of iron oxide — the same compounds that cause blood and rust form their distinct color.
With that in mind, it’s no coincidence that Mars, which occasionally appears as a bright red “star,” was named after the Greek god of war.
It’s not entirely clear how all that iron oxide ended up on the planet’s surface, but we do know that the planet formed about 4.5 billion years ago, when debris, gas, and dust began to coalesce. Among these materials was much iron, forged in the hearts of stars long dead.
Earth and Mars are both rich in iron, but while the heavy elements sank into Earth’s core when the planet was young and squishy, scientists believe iron was incorporated less homogeneously into Mars due to its weaker gravity and smaller size. That’s not to say Mars doesn’t also have an iron core, but there’s still plenty of metal to be found in the upper crust.
However, iron itself is not red – its color usually ranges from . What happened was that all of the iron on the surface oxidized, forming iron oxide commonly known as rust – a compound of two iron atoms and three oxygen atoms.
But why was so much iron oxidized on the surface of Mars?
Scientists aren’t sure, but there’s reason to believe this massive oxidation occurred when Mars had flowing water and a dense atmosphere — possibly not all that different from Earth today. If you leave an iron-rich pot or spoon outdoors or in water for a long time, it will rust. A very similar process covered Mars with iron oxide.
An alternative theory, first proposed by Albert Yen of NASA’s Jet Propulsion Laboratory and based on data collected by the Pathfinder mission in 1997, suggests that much of this iron oxide comes from meteorites.
The rust layer is very thin and Mars has such large storms that they sometimes cover the entire planet. Beneath this layer is a volcanic rock that is very similar to Earth. Mars has some of the largest dust storms in the galaxy, whipping red dust into the light atmosphere around the planet. This is why the images of Mars appear to have a red sky.
Scientists think Mars may have once been very similar to Earth, but when it lost most of its atmosphere, ancient volcanoes blew out all the iron at its center and scattered it all over the planet.
In November 2013, NASA sent the MAVEN mission to Mars in hopes of getting more information about what Mars is made of. They note that Mars may not have water on the surface but may contain water deep below. Meanwhile, scientists have been conducting experiments to see if rust can be made without water. A few of them figured out how to make rust without even having water.
We all know that the earth has polar ice caps that are filled with frozen water. Well, it appears that Mars also has polar ice caps. With the help of MAVEN we should be able to see if the polar caps are made of ice water.
So Mars is red because it has a layer of rusty dust covering the entire surface, and if the scientists are right, it blows some of it out into space and then produces more. When it produces more, it is blown across the planet by the dust storms and it retains its red color. Mars has polar ice caps and we hope to find out soon if they are made of water.
So where does that redness come from?
Well, many rocks on Mars are full of iron, and when exposed to nature they “oxidize” and turn reddish – just like an old bicycle sitting in the backyard rusts.
When rusty dust is kicked up into the atmosphere from these rocks, it turns the Martian sky pink.
From a long way away, the whole planet looks kind of reddish.
But if you get a close-up — with an orbiter, lander, or rover — you’ll see that many Mars are actually more of a butterscotch colour.
Why Is Mars Called the Red Planet?
Mars is sometimes called the Red Planet. It’s red because of rusty iron in the ground.
Like Earth, Mars has seasons, polar ice caps, volcanoes, canyons, and weather. It has a very thin atmosphere of carbon dioxide, nitrogen and argon.
There are signs of ancient floods on Mars, but water now exists mostly in icy dirt and thin clouds. There is evidence of liquid salt water in the soil on some slopes of Mars.