On Saturn’s moon Titan, scientists catch waves in methane lakes
Now that spring is here, maybe it’s time to grab your surfboard and head to some far-off coastline -- perhaps as far as the outer solar system. Scientists using NASA’s Cassini spacecraft have found hints of waves sloshing on Titan, Saturn’s largest moon – the first time waves like those in Earth’s oceans have ever been found on another world.
Titan is the second largest moon in the solar system, after Jupiter’s moon Ganymede, and it’s sometimes called a planet-like moon: It’s the only other world in our neighborhood to feature stable bodies of liquid on its surface, and it has a thick atmosphere made mostly of nitrogen.
That doesn’t mean it would be a good vacation spot, however; those dark lakes and seas, which mostly cluster around the north pole, are filled with liquid methane and ethane. Regardless, Titan is one of the few spots in our solar system that some astrobiologists argue could potentially host some form of life, or the precursors to it.
Naturally, scientists wanted to see if they could see any movement on these lakes, as it could tell them more about atmospheric dynamics – particularly the winds, because waves are caused by winds transferring their kinetic energy into the liquid.
Scientists had never seen waves on Titan, in part because methane is viscous and doesn’t easily budge. Perhaps there simply wasn’t enough wind to move the thick liquid around. But other researchers had earlier wondered if they simply hadn’t caught the breeze at the right time. Some theorized that the winds would grow stronger in the north as the spring season approached, but until recently they couldn’t confirm it. They had to wait for spring to come around for Saturn and its moons, and that takes a while: The ringed gas giant’s year is 29 Earth-years long.
When it did in 2012, the scientists used Cassini’s Visual and Infrared Mapping Spectrometer to stare at the northern lakes. In one called Punga Mare, they saw “four distinct pixels” in the light that indicated some roughness on the liquid’s surface. While there’s a chance that the glint is coming from liquid-covered mudflats rather than waves, the researchers say their best-fit model indicates that they’re actual waves.
“If correct,” the study authors wrote, “this discovery represents the first sea-surface waves known outside of Earth.”
But don’t go grabbing your shortboard just yet. These monster waves reached terrifying heights of roughly 2 centimeters, the authors wrote.
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