title: Size and shape of Saturn's moon Titan.
abstract: 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 kilometers (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 orbiting closer to Saturn than Titan presently does. Titan's lack of high relief implies that most--but not all--of the surface features observed with the Cassini imaging subsystem and synthetic aperture radar 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.
authors.affiliation: Department of Geophysics, Stanford University, Stanford, CA 94305, USA. zebker@stanford.edu
authors.forename: Howard A
authors.initials: HA
authors.lastname: Zebker
authors.forename: Bryan
authors.initials: B
authors.lastname: Stiles
authors.forename: Scott
authors.initials: S
authors.lastname: Hensley
authors.forename: Ralph
authors.initials: R
authors.lastname: Lorenz
authors.forename: Randolph L
authors.initials: RL
authors.lastname: Kirk
authors.forename: Jonathan
authors.initials: J
authors.lastname: Lunine