Before 2004, we knew very little about Saturn’s Mercury-sized moon, Titan — save that it had a dense, nitrogen-rich atmosphere. But over the course of 13 years, the Cassini spacecraft completed more than 100 flybys of Titan, constantly collecting data on the mysterious moon. In 2005, Cassini even deployed its Huygens probe to the surface of the alien world, marking the first time we’ve landed on an outer solar system object. Thanks to the Cassini-Huygens mission, researchers learned that Titan hosts a surprisingly vast and varied landscape, speckled with lakes and seas of liquid methane and ethane, which are replenished by rains from hydrocarbon clouds.Now, according to a recent study published in Nature Geoscience, a team of UCLA planetary scientists and geologists found that these hydrocarbon clouds are not just gently drizzling rain over the surface of the moon. Instead, the researchers discovered that Titan experiences monsoon-like downpours capable of dumping enormous amounts of methane rain in very short periods of time.UCLA associate professor of planetary science and co-author of the study, Jonathan Mitchell, said in a press release , “The most intense methane storms in our climate model dump at least a foot of rain a day, which comes close to what we saw in Houston from Hurricane Harvey this summer.”Although Titan’s storms are very intense, they are also relatively rare. They occur only about once per Titan year, which is equivalent to about 30 Earth years. Even if the Titan storms are rare when compared to Earth, they are still much more frequent than scientists anticipated. “I would have thought these would be once-a-millennium events, if even that,” said Mitchell, “So this is quite a surprise.”