Wind, Not Water, May Explain Red Planet's Hue

Mars is red now (left), but it may have looked charcoal (right) in the past
(Image: NASA/ESA/Hubble Team)

From New Scientist:

Mars's distinctive red hue may be the result of thousands of years of wind-borne sand particles colliding with one another – and not rust, a new study argues.

Scientists generally agree that Mars's red colour is caused when a dark form of iron called magnetite oxidises into a reddish-orange form called haematite.

Just how the transformation came about is a matter of debate. Many researchers say water caused the oxidation. But some argue that hydrogen peroxide and ozone, which might be created when ultraviolet light breaks down carbon dioxide and oxygen in the Martian atmosphere, could be to blame.

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