Mars has been a subject of fascination for humans due to its unique colour. Nicknamed the ‘Red Planet’ for its iconic rusty hue, the question is what exactly gives the planet its colour?

Scientists have learned from space orbiters and landers that the rust-coloured dust called ferrihydrite that covers the planet is what gives Mars its red hue, CNN reported. Similar to the process on Earth, when iron in the rocks interacted with water or water and oxygen in the atmosphere on Mars, it created iron oxide. 

Martian winds, then, carried the iron oxide across Mars over billions of years, breaking it down into dust and giving the planet its signature colour. 

Since Mars no longer has liquid water, scientists previously believed that its rust-red colour came from dry iron oxides like hematite in the dust. However, according to a new analysis of satellite data and laboratory procedures, ferrihydrite might be a better explanation for the planet’s red colour. 

“The fundamental question of why Mars is red has been pondered for hundreds, if not thousands, of years,” said Adomas Valantinas, a lead author and a postdoctoral fellow in the Department of Earth, environmental and planetary sciences at Brown University, as per USA Today. 

He added, “Mars is still the Red Planet. It’s just that our understanding of why Mars is red has been transformed.”

Ferrihydrite’s identification as a major constituent of Martian dust may have significant implications for our knowledge of Mars’ past and the potential for extraterrestrial life. According to Valantinas, ferrihydrite’s existence on Mars indicates that the planet originally had a liquid water environment, which is essential for life.

Study co-author Jack Mustard said that the research offers a “door-opening opportunity”. He emphasised that although the results were encouraging, they could only be verified with actual samples taken from Mars.

NASA’s Perseverance rover is now gathering them, and when it returns to Earth, scientists will be able to confirm if the ferrihydrite idea is accurate.