Evidence of changing weather patterns in the skies over Titan's southern
region are revealed in these false color images obtained by the Cassini
spacecraft's visual infrared mapping spectrometer over two recent flybys
of this largest of Saturn's satellites. In the first image (left),
obtained on the Oct, 26, 2004 Titan flyby, from a distance of some
200,000 kilometers (124,300 miles), Titan's skies are cloud-free, except
for a patch of clouds observed over the south pole near the bottom of the
image. In contrast, the image on the right shows a recent view of this
same area of Titan obtained seven weeks later on the second close Titan
flyby on Dec. 13, 2004, from a distance of 225,000 kilometers (139,800
miles). This image clearly shows that several extensive patches of clouds
have formed over temperate latitudes. The appearance of these clouds
reveals the existence of weather. Tracking these features is currently
underway by scientists, who hope to gain a better understanding of global
circulation, regional weather patterns, and localized meteorology in
Titan's skies.
The colors red, green, and blue represent near-infrared images obtained
at 2.01 micron, 2.83 micron and 2.13 micron, respectively. These colors
explore the surface and atmosphere of Titan with varying effectiveness.
The red color images the surface at a wavelength (2.01 micron) where the
surface is relatively bright, making the surface appear reddish in these
color images. The green color (2.83 micron) images the surface as well,
but due to enhanced absorption of sunlight by the surface and lower
atmosphere, the surface is relatively dark here compared to the red. The
blue color (2.13 micron) is at a wavelength where sunlight cannot reach
the surface at all due to strong absorption by the atmospheric gas
methane. In contrast to the reddish surface, bright clouds at a
relatively high altitude (here, about 30 kilometers (19 miles) above the
ground) residing above most of the atmospheric absorption appear whitish
in these representations, as they reflect sunlight effectively in all
three near-infrared colors.
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 Cassini-Huygens 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 visible and
infrared mapping spectrometer team is based at the University of Arizona,
Tucson.
For more information about the Cassini-Huygens mission visit,
http://saturn.jpl.nasa.gov. For more information about the
visual and infrared mapping spectrometer visit
http://wwwvims.lpl.arizona.edu/.
