AAS 205th Meeting, 9-13 January 2005
Session 29 Planetary Systems and Origins of Planetary Bodies
Oral, Monday, January 10, 2005, 10:00-11:30am, Town and Country

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[29.01] The Origin of the Moon and Triton

F. M. Johnson (Cal State University Fullerton)

In 1879, George Darwin(1) had proposed that the moon originated from a rapidly spinning Earth on which equatorial gravitative attraction was nearly overcome by centrifical force. During a 1964 conference, D.U. Wise(2) and others analyzed this hypothesis in greater detail. However, recent studies warranted a fundamentally new approach with regards to the origin of the solar system.

A re-examination of the spin-off (fission) hypothesis of the moon from the earth, using slightly different assumptions than scientists had previously used (allowing for a more extreme version of an expanding earth), provided the earth’s original radius (357 km), density (3.13 x 104 g/cc) and spin rate (0.132 radians/sec.). It was found that Neptune underwent a similar development with the fission of Triton. The remarkably large initial densities, of both Earth and Neptune (7.2 x 105 gm/cc) are consistent with the overall theory(3,4) previously discussed regarding the evolution of the solar system from a neutron star type proto-sun’s dense core. The primary calculations involve conservation of angular momentum of each of the rotating and revolving planetary systems.

(1) Darwin, G. H. Phil. Trans. Roy. Soc. (London) 170, 1 (1879)

(2) D.U. Wise, ``The Earth-Moon System” p. 213, Marsden and Cameron Eds. Plenum Press (1966)

(3) Fred M. Johnson, ``Voyage Into Astronomy”, Kendall/ Hunt Publ., (1977)

(4) Fred M. Johnson, Mem. Soc. Roy. des Sciences de Liége, 6th series, vol. III, p. 609-627 (1972).

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