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planetesimal |
Also found in: Dictionary/thesaurus, Wikipedia, Hutchinson | 0.05 sec. |
planetesimalOne of a class of bodies that are theorized to have formed the planets after condensing from diffuse matter early in the history of the solar system. According to the nebular hypothesis, part of an interstellar cloud of dust and gas underwent gravitational contraction to form a solar nebula comprising a disk of matter with a central hub. As the disk contracted further, clumps of matter left behind in its midplane coalesced successively into bodies the size of pebbles and boulders and then into planetesimals up to several hundred miles across. These then combined under the force of gravity to form protoplanets, precursors of most of the current planets. How to thank TFD for its existence? Tell a friend about us, add a link to this page, add the site to iGoogle, or visit webmaster's page for free fun content. |
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The presence of aluminum-26 in a meteorite whose parent asteroid is known to have undergone early melting "helps buttress the case for aluminum-26 having been a major source of energy for planetesimal heating," he adds. As a theoretician, Ward has contributed fundamental insights to humankind's understanding of planetesimal formation, the origin and dynamical evolution of the moon, planet migration, planetary obliquity mechanics, and the formation of planetary and satellite systems. |
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