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.

Mars is easily identifiable in the night sky by its prominent red hue. Thanks to the fleet of spacecraft that have studied the planet over the last decades, we know that this red color is due to rusted iron minerals in the dust.

A new study led by Brown University researchers shows how a water-rich mineral could explain the planet’s color, hinting at a wetter, more habitable past on the Red Planet.