Saturn’s most metallic moon has become even more intriguing. On Titan, methane clouds release cold, oily rain – not unlike the water-based showers we see on Earth. Scientists have gathered evidence of cloud convection in Titan’s northern hemisphere for the first time by watching methane clouds on the moon shift over time over its eerie lakes.
By combining data from the Webb Space Telescope and Keck Observatory in Hawaii, the team of scientists observed Titan’s clouds rise to higher altitudes over time. This new discovery is the first to document cloud convection in the moon’s northern hemisphere, where most of Titan’s lakes and seas of liquid methane are located. The results of the study are detailed in an article published this week in the journal Nature.
“This allows us to better understand Titan’s climate cycle, how methane clouds can generate rain and replenish methane evaporating from the lakes,” said Conor Nixon, a research scientist at NASA‘s Goddard Space Flight Center and lead author of the study, in a statement.
Titan is the only moon in the solar system that has a significant atmosphere, but Saturn’s largest moon is shrouded in a layer of yellowish smog. To explore different depths in Titan’s atmosphere, the scientists used different Webb and Keck infrared filters to estimate the height of the clouds. The research team observed Titan in November 2022 and July 2023, recording clouds in the middle and high northern latitudes of the moon. Using space-based and ground-based observations, the scientists watched the clouds as they appeared to move to higher altitudes over several days. However, they were unable to directly see the precipitation falling.
According to NASA, Titan is the only place in the solar system where there is a similar fluid cycle to the Earth’s: rain pours out of the clouds, runs down its surface, fills lakes and seas, and evaporates back into the sky. But instead of water, Titan has liquid methane and ethane.
The strange moon is of great interest to astronomers because, despite its low temperatures and gaseous reservoirs, it contains complex organic chemistry. Organic molecules are one of the building blocks of life on Earth, and studying Titan helps scientists better understand how different life forms could have evolved in radically different planetary environments.
Recent discoveries are also helping scientists understand how different worlds evolve over time. “On Titan, methane is a consumable material,” says Nixon. “It’s quite possible that it’s been constantly being replenished and released from the crust and interior for billions of years. If not, it will eventually disappear, and Titan will become a mostly airless world of dust and dunes.”
