Although it is far too cold for blossoming flowers, summer does bring
storm clouds and presumably rain to Titan's south polar region. The
observed persistence of convective storm activity in the region during
the southern Titan summer has led scientists to speculate that the dark,
footprint-shaped feature near the upper left could be a past or present
reservoir for Titan's methane rains.
This series of three Cassini narrow-angle camera images, centered on the
pole, shows the evolution of bright clouds in the region over the course
of two hours during Cassini's distant June 6, 2005, flyby of the
planet-sized moon.
The appearance of the feature seen here is unique among the dark terrains
observed thus far on Titan. Other dark areas appear to have angular or
diffuse boundaries, while this one possesses a smooth perimeter,
suggestive of an eroded shoreline.
In addition to the notion that the dark feature is or was a lake filled
with liquid hydrocarbons, scientists have speculated about other
possibilities. For instance, it is plausible that the lake is simply a
broad depression filled by dark, solid hydrocarbons falling from the
atmosphere onto Titan's surface. In this case, the smoothed outline might
be the result of a process unrelated to rainfall, such as a sinkhole or a
volcanic caldera.
A still image of the south polar region from the same time period is also
available (see PIA06240).
The images in this movie sequence were taken using a combination of
spectral filters sensitive to wavelengths of polarized infrared light,
allowing Cassini to see through the obscuring smog of Titan's atmosphere
and down to the surface. The images were acquired from an approximate
distance of 450,000 kilometers (279,000 miles) from Titan. Resolution in
the original images is approximately 3 kilometers (2 miles) per pixel;
the images were aligned and reprocessed at the same scale to create the
movie.
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.
For additional images visit the Cassini imaging team homepage http://ciclops.org.
