The Origin of the Earth

AUG 01, 1994

Data from recent exploration of the solar system and telescopic observations of accretion discs around other stars make a model of Earth’s origin more quantitative.

DOI: 10.1063/1.881436

Thomas J. Ahrens

The question of the origin of the blue planet pictured in figure 1 is related to other questions about our beginnings. These include the origin of the universe, the evolution of galaxies and stars, the origin of life and the ascent of humankind. In the late 1700s both Pierre‐Simon Laplace and Immanuel Kant suggested that Earth and the other planets in the solar system had condensed from a flattened nebular disk surrounding the Sun. Since these astute hypotheses were suggested, a series of well‐known physical scientists including James Jeans, Gerald Kuiper and Harold Urey have developed a now widely accepted theory of the accretion of the Earth and planets. Their theory, which I describe below, was based on telescopic observations of the solar system, theoretical calculations and the study of meteorites. Now referred to as the Schmidt theory (after Otto Yu. Schmidt of the Institute of the Earth, Moscow), it explains the formation of the planets as resulting from the accretion of already solid bodies.

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References

1. L. B. Slichter, Proc. Natl. Acad. Sci. USA 36, 511 (1950).https://doi.org/PNASA6
2. R. Maars, P. D. Kinny, I. S. Williams, D. O. Froude, W. Compston, Geochim. Cosmochim. Acta 56, 1281 (1992).https://doi.org/GCACAK
3. C. C. Patterson, H. Brown, G. Tilton, M. Ingraham, Phys. Rev. 92, 1234 (1953).https://doi.org/PHRVAO
4. B. J. Levin, in The Upper Mantle, A. R. Ritsema, ed., Elsevier, Amsterdam (1972), p. 7.
5. F. Hoyle, Quart. J. R. Astron. Soc. 1, 28 (1960).
6. G. P. Kuiper, in Astrophysics, J. A. Hynek, ed., McGraw‐Hill, New York (1951), p. 357.
7. A. G. W. Cameron, Icarus 1, 13 (1962).https://doi.org/ICRSA5
8. D. J. Stevenson, Icarus 74, 542 (1985).https://doi.org/ICRSA5
9. V. S. Safronov, Evolution of the Proto‐Planetary Cloud and Formation of the Earth and Planets, publ. NASA‐TT‐F677, NASA, Washington, D.C. (1969).
10. G. W. Wetherill, Annu. Rev. Earth Planet. Sci. 18, 205 (1990).
11. W. Benz, A. G. W. Cameron, H. J. Melosh, Icarus 81, 113 (1989).https://doi.org/ICRSA5
12. B. A. Smith, R. J. Terrile, Science 226, 1421 (1984).https://doi.org/SCIEAS
13. D. J. Stevenson, in Origin of the Earth, J. Jones, H. Newsom, eds., Oxford U.P., Oxford (1990), p. 231.
14. T. J. Ahrens, in Origin of the Earth, J. Jones, H. Newsom, eds., Oxford U.P., Oxford (1990), p. 211.
15. A. E. Ringwood, Origin of the Earth and Moon, Springer‐Verlag, New York (1979).

More about the Authors

Thomas J. Ahrens. California Institute of Technology, Pasadena, California.