Models of Saturn's rings which satisfy the optical observations

A theoretical model of Saturn's rings is investigated which includes the shadowing effect and realistic anisotropic phase functions for the ring particles. The effects of multiple scattering and the finite size of the Sun, including the penumbra, are rigorously included. The permissible range of the relevant parameters, including optical thickness, single scattering albedo, volume density and phase function are investigated by comparing the theoretical results to observations of the ring brightness vs phase angle, wavelength, and elevation of the Sun and Earth. Anisotropic scattering by the ring particles is necessary in order to match the observations. The color dependence of the opposition effect is interpreted in terms of the albedo spectrum of the ring particles. (Auth.)