The Interior Structure of the Moon: What Does Geophysics Have to Say?

Geophysical data obtained from orbit and surface stations show that the Moon is a differentiated body possessing a crust, mantle, and core. The crust is on average about 40 km thick, and impact events with asteroids and comets have excavated materials to great depths within the crust. Moonquakes that are correlated in time with Earth-raised tides occur about halfway to the center of the Moon and suggest that the deepest portion of the mantle might be partially molten. The lunar core is relatively small in comparison with the cores of the terrestrial planets, with a size less than one-quarter of the Moon’s radius.