Jupiter and Saturn rotation periods

Anderson and Schubert [2007. Saturnʹs Gravitational field, internal rotation, and interior structure. Science 317, 1384–1387 (paper I)] proposed that Saturnʹs rotation period can be ascertained by minimizing the dynamic heights of the 100 mbar isosurface with respect to the geoid; they derived a rotation period of 10 h 32 m 35 s. We investigate the same approach for Jupiter to see if the Jovian rotation period is predicted by minimizing the dynamical heights of its isobaric (1 bar pressure level) surface using zonal wind data. A rotation period of 9 h 54 m 29.7 s is found. Further, we investigate the minimization method by fitting Pioneer and Voyager occultation radii for both Jupiter and Saturn. Rotation periods of 9 h 55 m 30 s and 10 h 32 m 35 s are found to minimize the dynamical heights for Jupiter and Saturn, respectively. Though there is no dynamical principle requiring the minimization of the dynamical heights of an isobaric surface, the successful application of the method to Jupiter lends support to its relevance for Saturn. ive Jupiter and Saturn rotation periods using equilibrium theory to explain the difference between equatorial and polar radii. Rotation periods of 9 h 55 m 20 s and 10 h 31 m 49 s are found for Jupiter and Saturn, respectively. We show that both Jupiterʹs and Saturnʹs shapes can be derived using solid-body rotation, suggesting that zonal winds have a minor effect on the planetary shape for both planets. reement in the values of Saturnʹs rotation period predicted by the different approaches supports the conclusion that the planetʹs period of rotation is about 10 h 32 m.