minty3 writes "Planetary scientists believe they have observed waves rippling on one of Titan's seas. The findings, presented on March 17 at the Lunar and Planetary Science Conference, describes how the Cassini spacecraft captured images of sunlight glinting off the Punga Mare (abstract), suggesting they are not reflective sunlight but waves." The Planetary Society recently posted a nice breakdown of the basics about Titan's lakes: "To flow with liquid, those river valleys must have been filled with methane that came from higher elevations; it had to rain methane on Titan. Rainfall runs off, and then what? It must pool somewhere. What we learned from the Cassini orbiter at Saturn is that there are lakes on Titan. ... Rainfall, river runoff, lakes, evaporation into clouds, rainfall again. Cassini has seen clouds make storms on Titan. We have seen the whole cycle -- it's just like Earth's water cycle, but with a completely different substance [methane], and much, much colder."