Submitted on November 24, 2008
Accepted on March 20, 2009
Size and Shape of Saturn's Moon Titan
Howard A. Zebker 1*, Bryan Stiles 2, Scott Hensley 2, Ralph Lorenz 3, Randolph L. Kirk 4, Jonathan Lunine 5
1 Stanford University, Stanford, CA 94305, USA.
2 Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA.
3 Johns Hopkins University, 11100 Johns Hopkins Road, Laurel, MD 20723, USA.
4 U.S. Geological Survey, 2255 N. Gemini Drive, Flagstaff, AZ 86001, USA.
5 University of Arizona, Tucson, AZ 85721, USA.
* To whom correspondence should be addressed.
Howard A. Zebker , E-mail: zebker{at}stanford.edu
Cassini observations show that Saturn’s moon Titan is slightly oblate. A fourth order spherical harmonic expansion yields north polar, south polar, and mean equatorial radii of 2574.32 ± 0.05 km, 2574.36 ± 0.03 km, and 2574.91 ± 0.11 km, respectively; its mean radius is 2574.73 ± 0.09 km. Titan’s shape approximates a hydrostatic, synchronously rotating triaxial ellipsoid but is best fit by such a body closer to Saturn than its present orbital location. Titan’s lack of high relief implies that most – but not all – of the surface features observed with the Cassini imaging subsystem (ISS) and the synthetic aperture radar (SAR) are uncorrelated with topography and elevation. Titan’s depressed polar radii suggest that a constant geopotential hydrocarbon table could explain the confinement of the hydrocarbon lakes to high latitudes.
