In
planetary science,
planetary differentiation is the process of separating out different constituents of a planetary body as a consequence of their physical or chemical behaviour, where the body develops into compositionally distinct layers; the
denser materials of a
planet sink to the center, while less dense materials rise to the surface. Such a process tends to create a
core and
mantle. Sometimes a chemically distinct
crust forms on top of the mantle. The process of planetary differentiation has occurred on planets,
dwarf planets, the asteroid
4 Vesta, and
natural satellites (such as the
Moon).