US researchers have discovered that Saturn's moon Titan has low level clouds, a possible indication of methane rain. Previously scientists have believed that the satellite - with its atmosphere of nitrogen and methane - had exceedingly dry weather. Caitlin Griffith and colleagues used near-infrared spectroscopy to discover rapid changes the concentration of methane in Titan's atmosphere which is similar to the behaviour of rain cloud formation observed on the Earth (Nature 395 575).