Origin of the lunar farside highlands from Earthshine-induced global circulation in lunar magma ocean

The lunar farside highlands, referred to as the lunar farside thicker crust compared with the nearside crust, presents a challenge to the theory of formation and evolution of the Moon. Here, we show that, after the Moon reached synchronous rotation, Earthshine could induce global circulation in lunar magma ocean due to the imposed surface temperature gradient generated by the hot, post-giant impact Earth. The global circulation, generating downwellings on the farside and a deeper return flow on the nearside, results that magmas flow from the nearside to the farside in the shallow magma ocean while the the direction of flow is opposite in the deep magma ocean. Such flow in the shallow magma ocean would transport anorthositic crystals formed in the nearside to the farside. Furthermore, since the lunar farside is cooler than the nearside, crystallization is much more efficient at the farside, resulting that farside magmas transported from the nearside produce anorthositic crystals rapidly. The theory proposed here may provide a natural way of explaining the origin of the lunar farside highlands.