Theories for the origin of lunar magnetism

This paper reviews the major theories which have been proposed to explain the remanent magnetism found in the lunar crust. A total of nine different mechanisms for lunar magnetism are discussed and evaluated in the light of the theoretical and experimental constraints pertinent to lunar magnetism. We conclude that none of these theories in their present state of development satisfy all the known constraints. However, the theories which agree best with our present understanding of the Moon are meteorite impact magnetization, thermoelectric dynamo field generation, and an early solar wind field.