Titan's Methane Cycle

Titan, Saturn’s largest moon, has river channels, lakes, and seas of liquid hydrocarbons—mainly methane and ethane, not water. With an average surface temperature near 94 K (about −179 °C), methane can occur as a liquid at the surface and as a gas in the atmosphere. It evaporates, condenses into clouds, and falls as precipitation, feeding rivers and bodies of liquid. This methane-based hydrologic cycle resembles Earth’s water cycle in the roles of its processes, but Titan’s chemistry and environment are very different.