Saturn's giant moon Titan and a smaller moon, Enceladus (left), appear to have all the ingredients for life, including liquid water, a heat source, and organic chemistry. Titan is covered with lakes and seas filled with methane, ethane, and other organic compounds, while jets of water and ice squirt from deep below the icy crust of Enceladus. So far, there is no direct evidence of life, only the ingredients for life. This image was snapped by the Cassini spacecraft, which has been orbiting Saturn since 2004. [NASA/JPL/SSI]
Find out more in our radio program entitled Moon and Saturn.