Why is Mars red?
Quick Answer
Mars looks red because its surface dust is rich in iron oxide, essentially rust, which is blown across the planet and even into its thin atmosphere.
The Full Story
Iron minerals in Martian rocks reacted with water and oxygen long ago and broke down into fine, rusty dust that now coats much of the planet. Winds lift this dust high into the air, so even the Martian sky looks butterscotch by day, while sunsets there appear bluish. For decades scientists assumed the colour came mainly from hematite, a dry iron oxide, but a 2025 study pointed instead to ferrihydrite, an iron oxide that forms when water is present. If confirmed, that would mean Mars rusted during an ancient wetter era. Global dust storms can envelop the whole planet, and a huge one in 2018 blocked sunlight from the solar-powered Opportunity rover, ending its 15-year mission.
Key Facts
YouTube Angle
Suggested video title for this topic:
"The Rusty Planet — What Mars Colour Reveals About Its Watery Past"