A "New Hope" for Moon Formation: Presenting a Multiple Impact Pathway

Fuente: arXiv
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Main Authors: Davies, Harrison, Carter, Philip J., Eddershaw, Louis, Dou, Jingyao, Leinhardt, Zoë M.
Format: Preprint
Published: 2025
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author Davies, Harrison
Carter, Philip J.
Eddershaw, Louis
Dou, Jingyao
Leinhardt, Zoë M.
author_facet Davies, Harrison
Carter, Philip J.
Eddershaw, Louis
Dou, Jingyao
Leinhardt, Zoë M.
contents The leading hypothesis for the origin of the Moon, that of a single giant impact, faces significant challenges. These include either the need for an impactor with a near-identical composition to Earth or an extremely high-mass or high-energy impact to achieve near-complete material mixing. In this paper we explore an alternative, the "multiple impact hypothesis", which relaxes the compositional constraints on both the target and projectile, and allows for the consideration of more probable, less extreme impacts that steadily grow the Earth and Moon to their current size over several impact events. Using the hydrodynamical code SWIFT, we simulate "chains" of impacts and follow the growth of a moon around a planet analogous to our own. Our results demonstrate that chains of three or more impacts can produce systems comparable to the Earth-Moon system whilst achieving higher compositional similarities than the canonical giant impact scenario. This presents the multiple impact hypothesis as a promising alternative to the single large impact scenario for the origin of the Moon.
format Preprint
id arxiv_https___arxiv_org_abs_2512_10757
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A "New Hope" for Moon Formation: Presenting a Multiple Impact Pathway
Davies, Harrison
Carter, Philip J.
Eddershaw, Louis
Dou, Jingyao
Leinhardt, Zoë M.
Earth and Planetary Astrophysics
The leading hypothesis for the origin of the Moon, that of a single giant impact, faces significant challenges. These include either the need for an impactor with a near-identical composition to Earth or an extremely high-mass or high-energy impact to achieve near-complete material mixing. In this paper we explore an alternative, the "multiple impact hypothesis", which relaxes the compositional constraints on both the target and projectile, and allows for the consideration of more probable, less extreme impacts that steadily grow the Earth and Moon to their current size over several impact events. Using the hydrodynamical code SWIFT, we simulate "chains" of impacts and follow the growth of a moon around a planet analogous to our own. Our results demonstrate that chains of three or more impacts can produce systems comparable to the Earth-Moon system whilst achieving higher compositional similarities than the canonical giant impact scenario. This presents the multiple impact hypothesis as a promising alternative to the single large impact scenario for the origin of the Moon.
title A "New Hope" for Moon Formation: Presenting a Multiple Impact Pathway
topic Earth and Planetary Astrophysics
url https://arxiv.org/abs/2512.10757