For a long time, nobody knew what the surface of Titan looked like. One of Saturn's moons, a thick atmosphere of methane and other gases kept the surface obscured. It wasn't until the Huygens probe landed on the Titan's surface, and the Cassini orbiter used its infrared and radar sensors, that scientists were able to peer beyond the haze. 

With their newfound imagery of Titan, researchers learned that the moon is spotted and marked with liquid — not water, but hydrocarbons like ethane and methane. Now, a team of scientists has figure out how Titan's lakes form, reports Jessica Mendoza for The Christian Science Monitor.

Titan is home to three large seas called mares, the largest of which (the Kraken Mare) stretches about 680 miles long. Rivers of hydrocarbons flow from them. The many shallower lakes however, are generally in flat areas and didn't have rivers feeding them. Those depressions were a mystery for researchers who wondered how they formed, especially since they can change depth and shape. Geology on Earth gave them clues.