The STEM Way

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The STEM Way

Why is Mars red?

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The red color of Mars is because of lots of rusted iron on the surface of Mars. This is why Mars is called the Red planet. 

Try this  simple experiment on rust before you begin from

What you need

  • 4 jars with lids
  • wire wool
  • Water
  • Boiled water
  • Salt


  • Place a small piece of wire wool in each jar.
  • Label the jars as 1, 2, 3, 4
  • Pour water into your first jar labelled ‘1’ and put the lid on it.
  • Pour boiled water into the second jar labelled ‘2’ and put the lid on it.
  • Leave the third jar labelled ‘3’ open and exposed to the air (air contains water vapour).
  • Mix some salt with tap water and pour this into the fouth jar labelled ‘4’ and place the lid on it.
  • Leave the jars for one day.
  • Check the jars the next day and write down your observations.


You will observe that jar 4 forms rust( a reddish brown compound ) first  followed by 1 and 3.  Rust forms when iron and oxygen react in the presence of water and air.

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This will help us understand why Mars is red.

What is Mars?

Mars is a planet! it is one of the 8 planets orbiting our sun. Mars is the planet next to us (the Earth). It is the 4th planet revolving around the sun. Mars is very very cold.

FUN FACT: Sometimes it even snows on Mars. But these snowflakes are not made of water but of Carbon dioxide!!

What is mars made of?

The first 4 planets- Mercury, Venus, Earth and Mars are rocky planets.  These planets are made up of a lot of different metals, Iron being one of them.

Why is there so much iron on the surface of mars?

Earth has a lot of iron too but most of the iron is in the center of the earth.

Mars also has an iron core but it also has iron on the surface.

A long long time ago ancient volcanos blew out the iron, spreading it all over the planet.


Credit: wallstreetotc

Scientists also speculate that because Mars is smaller than Earth, the gravity of Mars is less than that of the Earth so a lot  of the iron stayed on the surface.

This is why the  soil on the surface of Mars is like dust but mostly of iron.

Why is the iron red?

Usually iron is black. But when iron reacts with oxygen  it forms a red compound called rust.

Over many years the iron in the soil of Mars reacted with oxygen turning it red. The sky also appears red because of dust storms on mars that carry the dust into the atmosphere.


Look at this image of NASA’s Mars rover stuck in massive deadly dust storm



FUN FACT:  The sunset on Mars appears blue.

Do you know why Mars is red?


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