16-05-2025
Saturn's Moon Titan Is Surprisingly Earth-Like, the Only Other Place with Weather Like Ours
We tend to think of the weather as mundane, the sort of boring things you talk about when you have nothing else to say, but in the scope of the solar system, it's one of the most interesting things going on. There are eight known planets, five known dwarf planets, and hundreds of known moons in our solar system, but only two of them have weather: Earth and Titan.
Saturn's moon Titan is almost featureless when seen in visible light, thanks to a thick blanket of atmospheric fog. But when astronomers look at it in infrared light, they suddenly see lakes and rivers, dunes and valleys, and a complex liquid cycle. Recently, astronomers peered at Titan using the JWST and Keck observatories, revealing new insight into Titan's bizarrely Earth-like weather.
While the crew of The Ark (streaming now on Peacock) made their way across light-years of space to visit Proxima centauri b, they might have had a better shot setting up closer to home. Titan isn't exactly habitable by human standards (it's way too cold and we couldn't breathe the air) but it's remarkably similar in many ways.
It has an atmosphere made of mostly nitrogen, just like on Earth, with an atmospheric pressure about 1.5 times that of Earth. Inside that atmosphere you'll find running rivers, lakes, seas, and weather with clouds and rain. The surface temperatures on Titan are so cold (about -290 Fahrenheit) that water exists as solid stone and, possibly, liquid water oceans deep underground.
Instead of water, Titan's surface liquid cycle centers on methane. It evaporates from methane lakes and seas, creates methane clouds in the atmosphere, and rains back down again. 'Titan is the only other place in our solar system that has weather like Earth, in the sense that it has clouds and rainfall onto a surface,' explained astronomer Conor Nixon of NASA's Goddard Space Flight Center in Greenbelt, Maryland, in a statement.
Astronomers used the James Webb Space Telescope (JWST) and Keck observatories during two observation windows, one in November 2022 and another in July 2023, to investigate the weather cycle on Titan. In those observations, they identified two bright areas of methane cloud cover in the mid and high northern latitudes.
It's the first time astronomers have seen evidence of convection in the northern parts of Titan. That's where most of the moon's methane lakes and seas are, covering an area roughly equivalent to the North American Great Lakes. That's where Titan's weather cycle starts, as methane evaporates from the rivers and lakes on the surface, creating clouds.
Keck and JWST investigated the layers of Titan's atmosphere to estimate the altitude of clouds and track their movement over time. In observations taken days apart, astronomers watched clouds rise to higher altitudes, where methane gets broken down by sunlight or energetic electrons from Saturn's magnetosphere. As methane breaks down, it creates methyl radicals like CH3 which combine to create other molecules like ethane. Finally, they condense and fall from the alien sky as rain, returning to the surface and completing the cycle.
Titan may not be the most comfortable place in the universe, but it's about as close to home as any place we've found.
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