Dynamical arguments which concern melting of the Moon

Abstract

This paper points out that the observed differences of the moments of inertia of the lunar globe about its principal axes - determined astronomically and verified more recently by laser rangings - are inconsistent with the assumption that the whole Moon was ever covered by a global layer of molten material, extending to a depth of a few hundred kilometres. Moreover, laser determinations of the shape of the Moon (along the tracks overflown by Apollo 15 -17 missions) make it quite clear that the Moon’s surface did not solidify from a global ocean of lava even 10-20 km deep. Therefore, any melting which occurred on the Moon (and produced the observed chemical differentiation of the crustal rocks) could have taken place only locally — over areas of the size of the lunar maria, but not over the Moon as a whole at the same time.