Waves Discovered on Saturn’s Moon Titan?

Titan's lakes
A false-color mosaic reveals hydrocarbon lakes on Titan, Saturn’s largest moon. Credit: NASA/JPL-Caltech/University of Arizona/University of Idaho

Surfers rejoice! Fresh waves are still out there to conquer—on Saturn’s moon Titan. There, astronomers report a first sighting of waves rolling on an alien sea.

Using its cloud-penetrating radar, the international Cassini spacecraft team mapped the frigid surface of Titan, the ringed planet’s largest moon. Titan is the only other planetary body in the solar system with seas of stable liquid on its surface.

However, with surface temperatures averaging around −292 degrees Fahrenheit (−180 degrees Celsius), it’s not water that fills its many giant lakes, but liquid methane.

Now, the most recent flyby of the hazy moon has revealed a distinct bright spot in the second-largest sea near the moon’s north pole. The spot appears to suddenly disappear almost as soon as it appears in the maps. (See related: “New Titan Photos Showcase Lakes and Salt-Flats.”)

Dubbed the “magic island,” this geologic mystery may be best explained by waves or bubbles floating on the surface of these methane lakes, according to a new study published in Nature Geoscience this week.

“This discovery tells us that the liquids in Titan’s northern hemisphere are not simply stagnant and unchanging, but rather that changes do occur,” said the lead author of the study, Jason Hofgartner, a Cornell University graduate student.

“We don’t know precisely what caused this ‘magic island’ to appear, but we’d like to study it further.”

This suggests to planetary scientists that what we may be witnessing are the first hints of Titan’s seas reacting to the seasons changing from spring to summer, just like what happens on Earth. (See related: “Saturn Moon Has Tropical ‘Great Salt Lake,’ Methane Marshes.”)

Windy weather may very well be kicking up waves on Titan. To Cassini’s radar, the results look like ghostly islands. Alternately, gas bubbles may be breaching the lake surface.

“Likely, several different processes—such as wind, rain, and tides—might affect the methane and ethane lakes on Titan,” Hofgartner said. “We want to see the similarities and differences from geological processes that occur here on Earth.

“Ultimately, it will help us to understand better our own liquid environments here on Earth.”

 See for Yourself

Saturn is easily visible as a bright, yellow-colored star shining high in the south after dusk.

It’s definitely worth training a small backyard telescope on the crown jewel of the solar system, not only because of its majestic rings but also for its retinue of moons. Even at low magnification, Titan should be readily picked up as a small, bright, starlike object adjacent to the ringed world.

Saturn’s moons are a lot fainter than Jupiter’s; however, since Titan currently shines at magnitude 8.6, it is a fairly easy target for small telescopes. The hazy moon takes just under 16 days to rotate around Saturn, so an observer can watch day to day how Titan’s position relative to the planet slowly changes.

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Wildlife

Andrew Fazekas, aka The Night Sky Guy, is a science writer, broadcaster, and lecturer who loves to share his passion for the wonders of the universe through all media. He is a regular contributor to National Geographic News and is the national cosmic correspondent for Canada’s Weather Network TV channel, space columnist for CBC Radio network, and a consultant for the Canadian Space Agency. As a member of the Royal Astronomical Society of Canada, Andrew has been observing the heavens from Montreal for over a quarter century and has never met a clear night sky he didn’t like.