It Rains On Titan Way More Than We Thought

It Rains On Titan Way More Than We Thought

If you ever find yourself on Titan, make sure you bring an umbrella. Because scientists have discovered this moon of Saturn has surprisingly intense rainstorms every year, much more frequently than thought.

These rainstorms are not like ones on Earth. On Titan, they dump liquid methane onto the surface, at least a foot a day on the rainiest days. That’s equivalent to the amount of water that Hurricane Harvey dropped on Houston.

A paper describing the findings was published in the journal Nature Geoscience. It suggests intense rainstorms occur on Titan less than once per Titan year (just over 29 Earth years). The most extreme storms appear to occur roughly every 20 to 30 Titan years, so about once every 600 to 900 Earth years.

“I would have thought these would be once-a-millennium events, if even that,” said senior author Jonathan Mitchell from the University of California, Los Angeles, in a statement. “So this is quite a surprise.”

The team used a climate model to map weather patterns on Titan. They found that extreme rainfall shaped the surface, backed up by detections of alluvial fans – the result of flowing water moving sediment – by the now-dead Cassini spacecraft.

Rainfall can cause large flows of sediment on Earth, leading to the formation of alluvial fans. We think something similar may happen on Mars, too.

On Titan, the fans appear to be mostly nearer the poles than the equator. This regional difference means that some parts of the moon likely experience more rain than others, hinting at how the climate is different across the surface. That’s pretty cool.


This is what an alluvial fan looks like on Earth. NASA/GSFC/METI/ERSDAC/JAROS/ASTER

While we knew that liquid methane tends to fall nearer the poles, this is the first study to look at extreme rainfall events, suggesting they may be responsible for alluvial fans. It’s thought that differences between wetter, cooler weather in higher latitudes and drier, warmer weather lower down may drive the storms.

Cassini wasn’t actually able to see rain on Titan, and it might be a long time before a mission goes back there to look for it. But Titan is unique in being the only place other than Earth with bodies of liquid on its surface. That it rains somewhat like our planet, too, makes this moon all the more Earth-like.

“We therefore suggest that, similarly to Earth but differently from Mars, active geomorphic work may be ongoing in the present climate on Titan,” the team wrote in their paper.

Currently, there is no mission to Titan in the works. Given how awesome it is though, hopefully we’ll be back in the near future. The chance of seeing rain on another world should be a pretty tempting reason.