Identification of the giant impactor Theia in lunar rocks

  title={Identification of the giant impactor Theia in lunar rocks},
  author={Daniel Herwartz and Andreas Pack and Bjarne Friedrichs and Addi Bischoff},
  pages={1146 - 1150}
An analysis of motes of the Moon maker How did the Moon form? According to the prevailing hypothesis, a Mars-sized body known as Theia smashed into Earth. Herwartz et al. analyzed fresh basalt samples from three Apollo landing sites and compared them with several samples of Earth's mantle. The oxygen isotope values measured in these lunar rocks differ significantly from the terrestrial material, supporting the giant-impact hypothesis. Science, this issue p. 1146 Isotopic oxygen measurements… 
Oxygen isotopic evidence for vigorous mixing during the Moon-forming giant impact
The results indicate that the late veneer impactors had an average Δ′17O within approximately 1 per mil of the terrestrial value, limiting possible sources for this late addition of mass to the Earth-Moon system.
Geochemical arguments for an Earth-like Moon-forming impactor
An inversion method is presented to calculate the Hf/W ratios and ϵ182W values of the proto-Earth and impactor mantles for a given Moon-forming impact scenario.
Isotopes as tracers of the sources of the lunar material and processes of lunar origin
  • K. Pahlevan
  • Geology, Physics
    Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
  • 2014
The development of new isotopic tracers sensitive to processes in the melt–vapour lunar disc are discussed and theoretical calculations of their behaviour and sample observations can constrain scenarios of post-impact evolution in the earliest history of the Earth–Moon system.
Distinct oxygen isotope compositions of the Earth and Moon
The virtually identical oxygen isotope compositions of the Earth and Moon revealed by Apollo return samples have been a challenging constraint for lunar formation models. For a giant impact scenario
Origin of the Earth and Moon
According to the giant impact hypothesis, the Moon formed from a disk created by an impact between the proto-Earth and an impactor. Three major models for this hypothesis are (a) standard model: a
Terrestrial magma ocean origin of the Moon
A conceptual framework for the origin of the Moon must explain both the chemical and the mechanical characteristics of the Earth–Moon system to be viable. The classic concept of an oblique giant
Oxygen isotopic evidence for accretion of Earth’s water before a high-energy Moon-forming giant impact
It is shown that the bulk of Earth’s water was delivered before the high-energy collision that led to the formation of the Moon and not later, as often proposed.


Late formation and prolonged differentiation of the Moon inferred from W isotopes in lunar metals
The Moon is thought to have formed from debris ejected by a giant impact with the early ‘proto’-Earth and, as a result of the high energies involved, the Moon would have melted to form a magma ocean.
Origin of the Moon in a giant impact near the end of the Earth's formation
This work reports a class of impacts that yield an iron-poor Moon, as well as the current masses and angular momentum of the Earth–Moon system, and suggests that the Moon formed near the very end of Earth's accumulation.
Silicon Isotope Evidence Against an Enstatite Chondrite Earth
Comparing the silicon (Si) isotope signatures of several extraterrestrial materials with terrestrial samples shows that they cannot be explained by core-formation scenarios involving a bulk Earth of enstatite chondrite composition, and a heterogeneous mixture of several types of chondritic meteorites is more likely.
The tungsten isotopic composition of the Earth’s mantle before the terminal bombardment
It is speculated that the decrease in mantle 182W/184W occurs during the Archean eon (about four to three billion years ago), potentially on the same timescale as a notable decrease in 142Nd/144Nd (refs 3 and 6).
Forming a Moon with an Earth-like Composition via a Giant Impact
Computer simulations show that a giant impact on early Earth could lead to a Moon with a composition similar to Earth’s, and simulate impacts involving larger impactors than previously considered that can produce a disk with the same composition as the planet's mantle, consistent with Earth-Moon compositional similarities.