Saturn's northern hemisphere is presently a serene blue, more befitting of
Uranus or Neptune, as seen in this natural color image from Cassini.
Light rays here travel a much longer path through the relatively
cloud-free upper atmosphere. Along this path, shorter wavelength blue
light rays are scattered effectively by gases in the atmosphere, and it
is this scattered light that gives the region its blue appearance. Why
the upper atmosphere in the northern hemisphere is so cloud-free is not
known, but may be related to colder temperatures brought on by the ring
shadows cast there.
Shadows cast by the rings surround the pole, looking almost like dark
atmospheric bands. The ring shadows at higher latitudes correspond to
locations on the ringplane that are farther from the planet--in other
words, the northernmost ring shadow in this view is made by the outer
edge of the A ring.
Spots of bright clouds also are visible throughout the region. This view
is similar to an infrared image obtained by Cassini at nearly the same
time (see PIA06567). The infrared view shows a great deal more detail
in the planet's atmosphere, however.
Images obtained using red, green and blue spectral filters were combined
to create this color view. The images were taken with the Cassini
spacecraft wide angle camera on Dec. 14, 2004, at a distance of 719,200
kilometers (446,900 miles) from Saturn. The image scale is about 39
kilometers (24 miles) per pixel.
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 and its two onboard cameras were
designed, developed and assembled at JPL. The imaging team is based at
the Space Science Institute, Boulder, Colo.
For more information about the Cassini-Huygens mission, visit
http://saturn.jpl.nasa.gov and the Cassini imaging team home page,
http://ciclops.org.