This view of Titan’s south pole reveals the intriguing dark feature named
Ontario Lacus and a host of smaller features dotting the south polar region.
The true nature of this feature, seen here at left of center, is not yet known
with absolute certainty. However, the feature’s darkness, the shore-like
smoothness of its perimeter, and its presence in an area where frequent
convective storm clouds have been observed by Cassini and Earth-based
astronomers made it the best candidate for an open body of liquid on Titan
when this image was taken in June 2005.
This interpretation has been strengthened by the sighting of features having
similar morphologies in Titan’s northern polar region during the flyby of Titan
in late February (see PIA08365). The possibility that these northern features,
the sizes of small seas, are either completely or partially filled with liquid
hydrocarbons is significantly strengthened by Cassini radar data that overlap
portions of the Imaging Science Subsystem-observed northern bodies, (see
PIA09182).
Previously, scientists had speculated that Ontario Lacus might simply be 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.
However, the strong likelihood that the northern polar features are lakes and
seas has made imaging scientists more confident that Ontario Lacus, and the
smaller dark features dotting the southern polar region of Titan, also hold liquid.
If correct, this new revelation would mean that each pole on Titan is a large
wetlands area.
The feature is named for Lake Ontario because its shape and length are similar,
though the Titan feature is much wider. In actual surface area, the feature is
roughly the size of Lake Victoria. However, if the relative sizes of Titan and
Earth are accounted for, Ontario Lacus covers roughly the same fraction of
Titan as does the Black Sea on Earth.
A red cross below the center in the scene marks the pole. The brightest features
seen here are methane clouds. A movie sequence showing the evolution of bright
clouds in the region during the same flyby is also available (see PIA06241).
This view is a composite of three narrow-angle camera images, taken over
several minutes during Cassini's distant June 6, 2005, flyby. The images were
combined to produce a sharper view of Titan’s surface. The images were taken
using a combination of spectral filters sensitive to wavelengths of polarized
infrared light. The images were acquired from approximately 450,000 kilometers
(279,000 miles) from Titan. Resolution in the scene is approximately 3 kilometers
(2 miles) per pixel. The view has been contrast enhanced to improve the overall
visibility of surface features.
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.
