Origin of the Moon by capture and its consequences
Article first published online: 3 JUN 2011
©1970. American Geophysical Union. All Rights Reserved.
Eos, Transactions American Geophysical Union
Volume 51, Issue 9, pages 637–641, September 1970
How to Cite
1970), Origin of the Moon by capture and its consequences, Eos Trans. AGU, 51(9), 637–641, doi:10.1029/EO051i009p00637.(
- Issue published online: 3 JUN 2011
- Article first published online: 3 JUN 2011
I am going to discuss four topics, ranging from celestial mechanics to speculative propositions regarding the early history of the solar system: (1) A new calculation of the orbit evolution of the moon that suggests the capture of the moon as a separate body in tidal interactions with the earth; (2) The consequences of this capture on the earth itself and on its early history; (3) The consequences of the capture on the moon, its thermal history, and its surface features; and (4) Some consequences to the early history of the solar system: the existence of many moon-like bodies in the inner part of the solar system; the angular momentum of Venus; the origin of Phobos and Deimos.
Of the many proposed modes of origin of the moon, some violate physical laws; many are in conflict with observations; all are improbable. Perhaps the least improbable—based on new tidal theory calculations and on the interpretation of lunar surface material data—is capture of the moon as it passed near the earth in a direct (prograde) orbit, shortly after the formation of moon and earth, about 4.5 billion years ago. (Capture of the moon from an initially retrograde orbit that had been proposed some years ago, leads to physically unacceptable consequences.) The effects of capture on the earth would have been cataclysmic, leading to intensive heating of its interior, to volcanism, and to the immediate formation of an atmosphere and hydrosphere. Thus capture of a moon may have given rise to the unique properties of the earth (in the solar system) and to the early evolution of life, about 3.5 billion years ago.