Date: November 9th 2006

Nov 9, 2006

Erica Hupp/Dwayne Brown Headquarters, Washington 202-358-1237/1726

Carolina Martinez Jet Propulsion Laboratory, Pasadena, Calif 818-354-9382

RELEASE: 06-344

NASA SEES INTO THE EYE OF A MONSTER STORM ON SATURN

NASA's Cassini spacecraft has seen something never before seen on another planet -- a hurricane-like storm at Saturn's South Pole with a well-developed eye, ringed by towering clouds

The "hurricane" spans a dark area inside a thick, brighter ring of clouds It is approximately 5,000 miles across, or two thirds the diameter of Earth

"It looks like a hurricane, but it doesn't behave like a hurricane," said Andrew Ingersoll, a member of Cassini's imaging team at the California Institute of Technology, Pasadena "Whatever it is, we're going to focus on the eye of this storm and find out why it's there "

A movie taken by Cassini's camera over a three-hour period reveals winds around Saturn's South Pole blowing clockwise at 350 miles per hour The camera also saw the shadow cast by a ring of towering clouds surrounding the pole, and two spiral arms of clouds extending from the central ring These ring clouds, 20 to 45 miles above those in the center of the storm, are two to five times taller than the clouds of thunderstorms and hurricanes on Earth

Eye-wall clouds are a distinguishing feature of hurricanes on Earth They form where moist air flows inward across the ocean's surface, rising vertically and releasing a heavy rain around an interior circle of descending air that is the eye of the storm itself Though it is uncertain whether such moist convection is driving Saturn's storm, the dark "eye" at the pole, the eye-wall clouds and the spiral arms together indicate a hurricane-like system

Distinctive eye-wall clouds have not been seen on any planet other than Earth Even Jupiter's Great Red Spot, much larger than Saturn's polar storm, has no eye or eye-wall, and is relatively calm at the center

This giant Saturnian storm is apparently different than hurricanes on Earth because it is locked to the pole and does not drift around like terrestrial hurricanes Also, since Saturn is a gaseous planet, the storm forms without an ocean at its base

In the Cassini imagery the eye looks dark at light wavelengths where methane gas absorbs the light and only the highest clouds are visible

"The clear skies over the eye appear to extend down to a level about twice as deep as the usual cloud level observed on Saturn," said Kevin H Baines, of Cassini's visual and infrared mapping spectrometer team at NASA's Jet Propulsion Laboratory, Pasadena, Calif "This gives us the deepest view yet into Saturn over a wide range of wavelengths, and reveals a mysterious set of dark clouds at the bottom of the eye "

Infrared images taken by the Keck I telescope in Mauna Kea, Hawaii, had previously shown Saturn's South Pole to be warm Cassini's composite infrared spectrometer has confirmed this with higher resolution temperature maps of the area The spectrometer observed a temperature increase of about 4 degrees Fahrenheit at the pole The instrument measured high temperatures in the upper troposphere and stratosphere, regions higher in the atmosphere than the clouds seen by the Cassini imaging instruments

"The winds decrease with height, and the atmosphere is sinking, compressing and heating over the South Pole," said Richard Achterberg, a member of Cassini's composite infrared spectrometer team at NASA's Goddard Spaceflight Center, Greenbelt, Md

Observations taken over the next few years, as the South Pole season changes from summer to fall, will help scientists understand the role seasons play in driving the dramatic meteorology at the south pole of Saturn

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency The Jet Propulsion Laboratory manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington

For a movie, high-resolution images, infrared images and Saturn temperature maps, visit:

http://www nasa gov/cassini

-end-

To subscribe to the list, send a message to: hqnews-subscribe@mediaservices nasa gov To remove your address from the list, send a message to: hqnews-unsubscribe@mediaservices nasa gov

The following information is a reminder of your current mailing list subscription:

You are subscribed to the following list: [list_name]

using the following email: BULK_EMAIL

You may automatically unsubscribe from this list at any time by visiting the following URL:

http://www aus-city com/cgi-bin/dada/mail cgi/u/[list]/

If the above URL is inoperable, make sure that you have copied the entire address Some mail readers will wrap a long URL and thus break this automatic unsubscribe mechanism

You may also change your subscription by visiting this list's main screen:

http://www aus-city com/cgi-bin/dada/mail cgi/list/[list]

If you're still having trouble, please contact the list owner at: