Teams of astronomers at the California Institute of Technology and the University of California at Berkeley have discovered methane clouds near the south pole of Titan. Titan is Saturn’s largest moon, larger than the planet Mercury, and is the only moon in our solar system with a thick atmosphere. Like Earth’s atmosphere, the atmosphere on Titan is mostly nitrogen. Unlike Earth, Titan is inhospitable to life due to the lack of atmospheric oxygen and its extremely cold surface temperatures (-183 C; -297 F). Along with nitrogen, Titan’s atmosphere contains a significant amount of methane. Earlier spectroscopic observations had hinted at the existence of clouds on Titan, but gave no clue as to their location.