Saturn’s most metal moon just got more intriguing. On Titan, clouds of methane unleash a cold, oily rain—very different from the water-based downpours we see on Earth. For the first time, scientists have collected evidence of cloud convection in Titan’s northern hemisphere, observing the moon’s methane clouds shifting over time above its eerie lakes.
By combining data from the Webb space telescope and the Keck Observatory in Hawaii, a group of scientists observed Titan’s clouds rising to higher altitudes over time. This new discovery marks the first time cloud convection is seen taking place in the moon’s northern hemisphere, where most of Titan’s lakes and seas of liquid methane are located. The findings are detailed in a study published this week in the journal Nature.
“This enables us to better understand Titan’s climate cycle, how the methane clouds may generate rain and replenish methane evaporated from the lakes,” Conor Nixon, research scientist with NASA Goddard Space Flight Center and lead author of the study, said in a statement.
Titan is the only moon in the solar system to host a substantial atmosphere, but Saturn’s largest moon is shrouded with a layer of yellowish smog. To probe different depths in Titan’s atmosphere, the scientists used various infrared filters on Webb and Keck to estimate the altitudes of the clouds. The team behind the study observed Titan in November 2022 and July 2023, capturing clouds in the moon’s mid and high northern latitudes. Using space and ground-based observations, the scientists observed the clouds as they appeared to move to higher altitudes over a period of days. They were, however, not able to directly see any precipitation occurring.
Titan is the only other place in the solar system known to have an Earth-like cycle of liquids, with rain pouring from clouds and flowing across its surface, filling lakes and seas, and evaporating back into the sky, according to NASA. But instead of water, Titan has liquid methane and ethane.
The strange moon is of high interest to astronomers as it holds complex organic chemistry despite its frigid temperatures and gaseous bodies of water. Organic molecules are among the building blocks of life on Earth, and studying Titan helps scientists better understand how different lifeforms could evolve under drastically different planetary circumstances.
The recent findings also help scientists understand how different worlds evolve over time. “On Titan, methane is a consumable,” Nixon said. “It’s possible that it is being constantly resupplied and fizzing out of the crust and interior over billions of years. If not, eventually it will all be gone and Titan will become a mostly airless world of dust and dunes.”
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