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NASA's Cassini Sees Abrupt Turn in Titan's Atmosphere

PASADENA, Calif. -Data from NASA's Cassini spacecraft tie a shift in seasonal sunlight to a wholesale reversal, at unexpected altitudes, inthe circulation of the atmosphere of Saturn's moon Titan. At the south pole, the data show definitive evidence for sinking air where it was upwelling earlier in the mission. So the key to circulation inthe atmosphere of Saturn's moon Titan turned out to be a certain slant of light. The paper was published today in the journal Nature.
"Cassini's up-close observations are likely the only ones we'llhave in our lifetime of a transition like this in action," said Nick Teanby, the study's lead author who is based at the University of Bristol, England, and is a Cassini team associate. "It'sextremely exciting to see such rapid changes on a body that usually changes so slowly and has a 'year' that is the equivalent of nearly 30 Earth years."
In our solar system, only Earth, Venus, Mars and Titanhave both a solid surface and a substantial atmosphere - providing natural laboratories for exploring climate processes. "Understanding Titan's atmosphere gives us clues for understanding our owncomplex atmosphere," said Scott Edgington, Cassini deputy project scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "Some of the complexity in both places arises from the interplay ofatmospheric circulation and chemistry."
The pole on Titan that is experiencing winter is typically pointed away from Earth due to orbital geometry. Because Cassini has been in orbit around Saturn since2004, it has been able to study the moon from angles impossible from Earth and watch changes develop over time. Models have predicted circulation changes for nearly 20 years, but Cassini has finallydirectly observed them happening - marking a major milestone in the mission.
Other Cassini instruments recently obtained images of the formation of haze and a vortex over Titan's south pole, but the...