  Mean densities of major and dwarf planets are possible to calculate by the
values of the planets distance to the Sun, the mean densities of massive
natural satellites of planets are computable by the satellites distance to the
Sun and the primary. The article hypothesizes that the mean density of a body
was affected by the gravitational field during the body formation in the
formation point, and the gravity was influenced by the Sun and a hypothetical
supermassive belt in the region beyond Neptune, and by the primary also, in
case of the natural satellites. The mean densities obtained by the traditional
methods and through the newly proposed approach characterize different life
stages of celestial bodies, and the comparative analysis of these mean density
values can be a useful tool in studying migration of the bodies in the Solar
System and in other planetary systems.
