Rainfall is one of the defining characteristics of our weather, with amounts varying dramatically from one region to another. It shapes both our skies and our landscape, carving valleys while filling rivers and lakes.
We know similar processes are also at work elsewhere. Titan, too, has rivers, lakes, valley networks and rain, even though the fluid involved is quite different — liquid methane instead of water.
Mars also seems to bear the marks of rainfall, albeit from some billions of years ago. Although gas giants such as Jupiter and Saturn have no surface, raindrops are thought to play a crucial role in the dramatic storms visible on their surfaces because the drops transport heat through the atmosphere.
