The origin of the moon and the early history of the earth—A chemical model. Part 1: The moon

The theories of Harold C. Urey (1893-1981) on the origin of the moon are discussed in relation to earlier ideas, especially George Howard Darwin's fission hypothesis. Urey's espousal of the idea that the moon had been captured by the earth and has preserved information about the earliest history of the solar system led him to advocate a manned lunar landing. Results from the Apollo missions, in particular the deficiency of siderophile elements in the lunar crust, led him to abandon the capture selenogony and tentatively adopt the fission hypothesis.

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Introductory remarks

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1982.0061 ◽

1982 ◽

Vol 306 (1492) ◽

pp. 9-10 ◽

Cited By ~ 1

Keyword(s):

Seismic Data ◽

Geomagnetic Field ◽

Early History ◽

The Moon ◽

The Core ◽

The Past ◽

The Earth ◽

History Of ◽

The Subject ◽

Additional Constraints

The suggestion for this Discussion Meeting was put forward more than three years ago. The format of the programme has changed many times since the original version, reflecting in part changing interests in different aspects of the subject. Of the 25 papers to be presented, only 5 discuss the constitution of the core, 13 deal with the geomagnetic field (including the secular variation and reversals) and all but 1 of the remaining 7 on geophysical interpretations are also concerned with the geomagnetic field. This emphasis on geomagnetism reflects the additional constraints that the absence or presence of a magnetic field may put on the constitution of all the planets and the Moon. In contrast to the Earth, the record of the first 10 9 years of planetary history is still at least partly preserved on the Moon, Mercury and Mars (and perhaps on Venus), and a study of this record on these other bodies may yield some information on the early history of the Earth. We have some seismic data for the Moon, but it is only for the Earth that we have a rich store of such data. In this connection, a word of caution is in order. It must not be forgotten that the structure of the Earth as revealed by seismic data is only a snapshot of what it is like today, and in many ways a very imperfect snapshot. There is no science of palaeoseismology, and seismic data tell us nothing about the structure of the Earth in the past nor of its evolution.

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The importance of tidal friction for the early history of the Moon

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1967.0023 ◽

1967 ◽

Vol 296 (1446) ◽

pp. 293-297 ◽

Cited By ~ 3

Keyword(s):

Body Problem ◽

Early History ◽

The Moon ◽

Tidal Friction ◽

Moon System ◽

Two Body Problem ◽

Dissipation Of Energy ◽

The Earth ◽

History Of ◽

Rotation Of The Earth

About ten years ago I began to investigate tidal friction and its influence on the evolution of the Earth-Moon system, and I first describe the model used. Following the ideas of G. H. Darwin, I treated the system as a two-body problem. The Moon raises tides on the Earth and the two bulges of the tidal ellipsoid, because of the rotation of the Earth, revolve twice daily. The line joining them forms an angle ψ with the line joining their centres; this is a measure of the dissipation of energy. The Moon, considered as a point mass, exerts a retarding couple on the deviated tidal ellipsoid. Contrary to Darwin, I have limited myself to the case of small angles ψ , but I have allowed for arbitrary changes of the other parameters of the orbit, for example, changes of the obliquity ∊ between the earth’s axis and the pole of the orbit as well as changes of the eccentricity.

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Geochemical Constraints on the Early Thermal History of the Earth

Zeitschrift für Naturforschung A ◽

10.1515/zna-1989-1003 ◽

1989 ◽

Vol 44 (10) ◽

pp. 883-890 ◽

Cited By ~ 12

Author(s):

Michael J. Drake

Keyword(s):

Upper Mantle ◽

Partition Coefficients ◽

Current Theory ◽

Gravitational Potential Energy ◽

The Moon ◽

The Core ◽

The Earth ◽

History Of ◽

Geochemical Constraints ◽

Origin Of The Moon

Abstract Theories of the formation of the Earth strongly suggest that the Earth should have been substantially molten during and immediately after accretion. Estimates of the composition of the upper mantle indicate that many elements are present in chondritic ratios. Experimental measurements of element partition coefficients show that segregation of perovskite, majorite garnet, or olivine would fractionate the ratios of these elements away from chondritic values. The implication of these geochemical observations is that the Earth did not undergo extensive fractionation during and immediately following accretion. One possibility is that the Earth did not become substantially molten. Alternatively, if the Earth was indeed substantially molten, then it is possible that minerals were entrained in magma and were unable to segregate. In the former case, the accretional process must have delivered gravitational potential energy more slowly than current theory predicts, and an origin of the Moon in a giant impact would be unlikely. In the latter case, the high Mg/Si ratio in the upper mantle of the Earth relative to most classes of chondrites would be intrinsic to the silicate portion of the Earth. Unless significant amounts of Si exist in the core, the high Mg/Si ratio is a bulk planetary property, implying that the accretional process did not mix material between 1 AU and 2-4 AU.

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The Origin of the Moon

Symposium - International Astronomical Union ◽

10.1017/s0074180900178209 ◽

1962 ◽

Vol 14 ◽

pp. 149-155 ◽

Cited By ~ 1

Author(s):

E. L. Ruskol

Keyword(s):

Chemical Composition ◽

Solar System ◽

The Moon ◽

The Earth ◽

The Difference ◽

Origin Of The Moon

The difference between average densities of the Moon and Earth was interpreted in the preceding report by Professor H. Urey as indicating a difference in their chemical composition. Therefore, Urey assumes the Moon's formation to have taken place far away from the Earth, under conditions differing substantially from the conditions of Earth's formation. In such a case, the Earth should have captured the Moon. As is admitted by Professor Urey himself, such a capture is a very improbable event. In addition, an assumption that the “lunar” dimensions were representative of protoplanetary bodies in the entire solar system encounters great difficulties.

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The Origin of the Moon and its Relationship to the Origin of the Solar System

Symposium - International Astronomical Union ◽

10.1017/s0074180900178192 ◽

1962 ◽

Vol 14 ◽

pp. 133-148 ◽

Cited By ~ 2

Author(s):

Harold C. Urey

Keyword(s):

Solar System ◽

The Moon ◽

The Past ◽

The Earth ◽

Short Period ◽

Origin Of The Moon

During the last 10 years, the writer has presented evidence indicating that the Moon was captured by the Earth and that the large collisions with its surface occurred within a surprisingly short period of time. These observations have been a continuous preoccupation during the past years and some explanation that seemed physically possible and reasonably probable has been sought.

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Isotopic evidence for the formation of the Moon in a canonical giant impact

Nature Communications ◽

10.1038/s41467-021-22155-7 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Sune G. Nielsen ◽

David V. Bekaert ◽

Maureen Auro

Keyword(s):

Solar System ◽

Isotope Fractionation ◽

Main Stage ◽

The Moon ◽

Giant Impact ◽

Bulk Silicate Earth ◽

The Earth ◽

The Standard Model ◽

Isotopic Measurements ◽

Origin Of The Moon

AbstractIsotopic measurements of lunar and terrestrial rocks have revealed that, unlike any other body in the solar system, the Moon is indistinguishable from the Earth for nearly every isotopic system. This observation, however, contradicts predictions by the standard model for the origin of the Moon, the canonical giant impact. Here we show that the vanadium isotopic composition of the Moon is offset from that of the bulk silicate Earth by 0.18 ± 0.04 parts per thousand towards the chondritic value. This offset most likely results from isotope fractionation on proto-Earth during the main stage of terrestrial core formation (pre-giant impact), followed by a canonical giant impact where ~80% of the Moon originates from the impactor of chondritic composition. Our data refute the possibility of post-giant impact equilibration between the Earth and Moon, and implies that the impactor and proto-Earth mainly accreted from a common isotopic reservoir in the inner solar system.

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