Impact origin of the moon?

Erik Asphaug

Research output: Contribution to journalReview articlepeer-review

69 Scopus citations


Earth formed in a series of giant impacts, and the last one made the Moon. This idea, an edifice of post-Apollo science, can explain the Moon's globally melted silicate composition, its lack of water and iron, and its anomalously large mass and angular momentum. But the theory is seriously called to question by increasingly detailed geochemical analysis of lunar rocks. Lunar samples should be easily distinguishable from Earth, because the Moon derives mostly from the impacting planet, in standard models of the theory. But lunar rocks are the same as Earth in O, Ti, Cr, W, K, and other species, to measurement precision. Some regard this as a repudiation of the theory; others say it wants a reformation. Ideas put forward to salvage or revise it are evaluated, alongside their relationships to past models and their implications for planet formation and Earth.

Original languageEnglish (US)
Pages (from-to)551-578
Number of pages28
JournalAnnual Review of Earth and Planetary Sciences
StatePublished - May 2014


  • Accretion
  • Collisions
  • Moon formation
  • Planets

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science


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