• DOI:10.1038/ngeo2866
• Corpus ID: 16658852

A multiple-impact origin for the Moon

@article{Rufu2017AMO,
  title={A multiple-impact origin for the Moon},
  author={Raluca Rufu and Oded Aharonson and Hagai B. Perets},
  journal={Nature Geoscience},
  year={2017},
  volume={10},
  pages={89-94}
}

• R. Rufu, O. Aharonson, H. Perets
• Published 1 February 2017
• Physics, Geology
• Nature Geoscience

The hypothesis of lunar origin by a single giant impact can explain some aspects of the Earth–Moon system. However, it is difficult to reconcile giant-impact models with the compositional similarity of the Earth and Moon without violating angular momentum constraints. Furthermore, successful giant-impact scenarios require very specific conditions such that they have a low probability of occurring. Here we present numerical simulations suggesting that the Moon could instead be the product of a succession of a variety of smaller collisions. In this scenario, each collision forms a debris disk around the proto-Earth that then accretes to form a moonlet. The moonlets tidally advance outward, and may coalesce to form the Moon. We find that sub-lunar moonlets are a common result of impacts expected onto the proto-Earth in the early Solar System and find that the planetary rotation is limited by impact angular momentum drain. We conclude that, assuming efficient merger of moonlets, a multiple-impact scenario can account for the formation of the Earth–Moon system with its present properties. A giant impact has been proposed as being responsible for forming the Moon, but scenarios that match existing constraints are improbable. Numerical modelling now suggests that instead a series of smaller and more common impacts can explain the Earth–Moon system.