Interior structure of Saturn

The authors summarize the principal observational data that constrain interior models of Saturn, and explain why they are relevant. They discuss the behavior of hydrogen, Saturn's major constituent, at pressures on the order of 0.1 to 10 Mbar and temperatures on the order of 10⁴K. Possible behavior and distributions of minor constituents are also considered, along with processes for their transport. The authors interpret Saturn's external gravitational and magnetic fields in terms of interior structure, and discuss the relationship between atmospheric zonal flows and the deep interior. The constraint imposed by tidal evolution considerations is evaluated. Calculations for the thermal evolution of Saturn are presented, both with and without consideration of possible gravitational unmixing. Possible scenarios for Saturn's mode of origin and their implications for presently observed atmospheric abundances are discussed.