The Structure and Evolution of the Lunar Interior

Abstract

[Introduction] The internal structure of the Moon, from surface to core, preserves a record of its evolution from accretion to present-day. The structure of the Moon is unique in the Solar System by virtue of its small core radius relative to its planetary radius, plagioclase-rich crust, and highly heterogeneous crustal distribution of heat producing elements. This bulk structure is largely a consequence of the accretion of the Moon from a circum-terrestrial impact-generated debris disk, and its subsequent differentiation from a magma ocean. However, the present-day Moon exhibits strong departures from the simple spherically symmetric stratified interior expected at the end of magma ocean crystallization. The observed structure, on scales ranging from meters to thousands of kilometers, is a result of the long and complicated evolution of the Moon, including effects of impacts, volcanism and magmatism, and tectonism. Thus, the physical structure of the Moon is intimately tied to its differentiation from a magma ocean (see Gaffney et al. 2023, this volume), the composition and evolution of its crust (see Elardo et al. 2023, this volume), its history of volcanism (see Head et al. 2023; Shearer et al. 2023, both this volume) and tectonism (see Nahm et al. 2023, this volume), and the effects of impacts of all scales (see Osinski et al. 2023, this volume).

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