This near-infrared movie of Saturn's north pole shows a giant cyclone,
encircled by a hexagon feature. The movie was created from several images,
taken by the visual and infrared mapping spectrometer onboard the Cassini
spacecraft.
The hexagon itself is populated by fast-moving clouds which reach speeds
of over 530 kilometers per hour (300 miles per hour). The discrete,
circular and oblong clouds dotting the image are likely convective
upwelling originating deep inside the planet, which help power the
cyclones. The movie shows clouds throughout the atmosphere, down to as
deep as 125 kilometers (78 miles) below the haze. Many of the features
seen are thought to be deep-level clouds of ammonia-hydrosulfide, which
rise to higher altitudes in convective updrafts.
This movie is centered on the pole and shows the cyclonic motions of rings
of clouds in the near-infrared wavelength of 5 microns, some seven times
the reddest wavelength observed by the human eye. The resolution is better
than 200 kilometers (124 miles) per pixel. The movie covers a six-hour
period at close range (as close as 240,000 kilometers, or 149,000 miles
above the clouds) from a nearly-overhead viewpoint. Winds reach over 150
meters per second (325 miles per hour) at 88.3 degrees south latitude,
just outside the first bright ring nearest the pole.
Normally Saturn's internal glow illuminates Saturn's deep clouds from
below, thus rendering the clouds in silhouette against this background
glow. Nevertheless, for the movie, the contrast has been reversed to show
the clouds as white, thus making the clouds appear more like they would if
seen in reflected light.
This movie was created from four images obtained on June 15 over a range
of distances between 224,000 and 422,000 kilometers (149,000 miles to
262,000 miles) above the clouds and a sub-spacecraft north latitude
ranging from 69 to 78 degrees.
A polar orthographic projection was used, with 0 degrees longitude toward
the top center, 90 degrees west longitude toward the right center, etc.,
based on the longitude system established by Voyager. Features are thus
seen flowing in Saturn's reference frame, with the planet's spin
eliminated.
The Cassini-Huygens mission is a cooperative project of NASA, the European
Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory,
a division of the California Institute of Technology in Pasadena, manages
the mission for NASA's Science Mission Directorate, Washington, D.C. The
Cassini orbiter was designed, developed and assembled at JPL. The Visual
and Infrared Mapping Spectrometer team is based at the University of
Arizona.
For more information about the Cassini-Huygens mission visit
http://saturn.jpl.nasa.gov/home/index.cfm. The visual and infrared mapping
spectrometer team homepage is at http://wwwvims.lpl.arizona.edu.
