& O'Hara, M.J. (2016). Is lunar magma ocean (LMO) gone with the wind? National Science Review 3
Author(s) from Durham
The Moon is the only natural satellite of the Earth, and has been the subject of numerous works of arts, literature, mythology, astrology and astronomy for millennia. The scientific speculation of its origin has also been in the literature for centuries. But it is the manned landing of Apollo missions 11–17 (1969–1972) with returned lunar rocks and soils and the unmanned post-Apollo spacecraft with remote-sensing data that allow the development of geological models on the origin of the Moon, its internal structure and its subsequent histories .
Several models have been proposed for the origin of the Moon, but the single generally accepted model today is the ‘giant impact’ hypothesis . It assumes that the Earth–Moon system formed as the result of a giant impact by a Mars-sized body that collided with the proto-Earth, blasting material into its orbit to form the Moon. This Moon formation mechanism would help explain the high angular momentum of the Earth–Moon system and the small size of the iron lunar core.
The energy released during such a giant impact would have been sufficient to melt the outer few hundreds of kilometers (<1000 km?) of the Moon, forming the postulated global lunar magma ocean (LMO; Fig. 1a). The evidence for this ‘LMO hypothesis’ came from the highly anorthositic compositions of the lunar highland crust. The ‘anorthositic compositions’ refer to rocks dominated by CaO-rich plagioclase (CaAl2Si2O8), which is less dense than the magma and would float to form the lunar crust and highlands (Fig. 1b) . This is the ‘plagioclase floatation hypothesis’. As noted , the ‘LMO hypothesis’ was initially based on a few anorthositic particles of Apollo 11 soil . These two interdependent hypotheses are actually based on a single …