TIDAL DISSIPATION IN THE SOLID CORES OF THE MAJOR PLANETS

If the orbital resonances in the Jovian and Saturnian satellite systems are the result of orbital evolution due to tidal dissipation then the present rates of energy dissipation ( E dot) are >2 × 1020 ergs sec-1 (Jupiter) and ≳2 × 1016 ergs sec-1 (Saturn). These values of E dot can be accounted for if the planets have rocky cores with volumes equal to those suggested by current models of the interiors and if the material of these cores is both solid and imperfectly elastic (Qe ∼ 34). The calculated values of Qe are not strongly dependent on either the rigidity of the core or the densities of the core and the mantle. Thus, these quantities need not be known precisely. It may be significant that approximately the same value of Qe is needed for all the major planets (Jupiter, Saturn, and Uranus) even though the values of E dot for these planets differ by a factor greater than 104. © 1979.