Cassini Spots Saturn's Moon Titan Naked in a Blast of Solar Wind

It turns out that Saturn's largest moon, Titan, behaves a lot like Mars and Venus. Scientists have studied data from NASA's Cassini mission and have found that unmagnetized bodies like Titan may interact with the solar wind in the same basic ways, despite their distance from the sun.

Titan is massive; in fact, it's large enough that it could be considered a planet if it orbited the sun on its own. A flyby of Titan in Dec. 2013 actually simulated this scenario from Cassini's vantage point; it was the only time that Cassini witness Titan outside the region of space dominated by Saturn's magnetic field.

"We observed that Titan interacts with the solar wind very much like Mars, if you moved it to the distance of Saturn," said Cesar Bertucci, one of the researchers, in a news release. "We thought Titan in this state would look different. We certainly were surprised."

Titan spends about 95 percent of its time in Saturn's magnetosphere. During the flyby, though, the moon happened to be on the sunward side of Saturn when a powerful burst of solar activity reached the planet. The strong surge in the solar wind compressed the sun-facing side of Saturn's magnetosphere, causing Titan to actually be on the outer edge of this magnetic field's "bubble." This, in turn, left the moon exposed to the stream of energetic solar particles. In the end, they found that Titan interacts with the wind much like other planets in the solar system.

"After nearly a decade in orbit, the Cassini mission has revealed once again that the Saturn system is full of surprises," said Michele Dougherty, principal investigator of the Cassini magnetometer, in a news release. "After more than a hundred flybys, we have finally encountered Titan out in the solar wind, which will allow us to better understand how such moons maintain or lose their atmospheres."

The findings are published in the journal Geophysical Research Letters.

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