CICLOPS: Cassini Imaging Central Laboratory for OPerationS

Cassini Sees Inner Workings In The Eye Of Saturn Cyclone

Carolyn Porco (720) 974-5849
CICLOPS/Space Science Institute, Boulder, Colo.

For Immediate Release: Oct. 13, 2008


New Cassini spacecraft views of the monstrous vortex at Saturn's south pole are providing valuable insight about the mechanisms that power the planet's atmosphere.

NASA's Cassini spacecraft acquired images of Saturn's south polar vortex on July 15 that are ten times more detailed than any seen before. Previous images revealed an outer ring of high clouds surrounding a region previously thought to be mostly clear air interspersed with a few puffy clouds that circulate around the center. The new images show that the puffy clouds are vigorous convective storms that form yet another distinct, inner ring.

"What looked like puffy clouds in lower resolution images are turning out to be deep convective structures seen through the atmospheric haze," said Cassini imaging team member Dr. Tony DelGenio of NASA's Goddard Institute for Space Studies in New York. "One of them has punched through to a higher altitude and created its own little vortex."

The "eye" of the vortex is surrounded by an outer ring of high clouds. This ring is 4,000 kilometers, or 2,500 miles, wide, and its high clouds cast shadows, indicating they are 40 to 70 kilometers, or 25 to 45 miles, above the clouds inside the ring. The new images hint at an inner ring about half the diameter of the main ring, and so the actual clear "eye" region is smaller than it appeared in earlier low-resolution images.

"It's like seeing into the eye of a hurricane," said Dr. Andrew Ingersoll, a member of Cassini's imaging team at the California Institute of Technology, Pasadena.

The ring is similar to the eyewall of a terrestrial hurricane, but much larger. The clear air there is warm, like the eye of a terrestrial hurricane, but on Saturn it is locked to the pole, whereas a terrestrial hurricane drifts around.

"It's intriguing," said Ingersoll. "Convection is an important part of the planet's energy budget because the warm upwelling air carries heat from the interior. In a terrestrial hurricane, the convection occurs in the eyewall; the eye is a region of downwelling. Here convection seems to occur in the eye as well. Jupiter surprised us in the same way: the most intense convection occurred in the regions of general downwelling."

Further observations are planned between now and southern fall equinox in August 2009 to see how the features evolve as the seasons change from summer to fall.

Images of Saturn's south polar vortex are available at:, and

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory (JPL), a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team consists of scientists from the U.S., England, France, and Germany. The imaging operations center and team leader (Dr. C. Porco) are based at the Space Science Institute in Boulder, Colo.


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