For centuries, Mars has captivated scientists and the public alike with its striking red hue. Early astronomers speculated that the planet’s color came from iron-rich minerals, much like rust on Earth.

A study suggests Mars takes its red hue from a type of mineral that forms in cool water, which could reveal insights about whether Mars was ever able to support life.

New research shows that the red dust on Mars contains ferrihydrite, a water-rich iron oxide. It's evidence that the planet rusted in water.