Comets, Meteors and Meteorites, Interplanetary Dust; Structure and Composition

  • Albrecht Unsöld
Part of the Heidelberg Science Library book series (HSL)


We begin with a short review of cometary orbits and some immediate inferences.
  1. a)

    The orbits of long-period comets with periods of the order 102 to 106 years show randomly distributed inclinations i, direct and retrograde motions being about equally likely. The eccentricities e are a little less than or nearly equal to 1 so that we have to do with elongated ellipses, or parabolas as limiting cases. Hyperbolic orbits (e> 1) are produced only occasionally as derivative consequences of perturbations by the large planets. Since at a large distance from the Sun the Velocity is very small, the comets must come from a cloud of such bodies that accompanies the Sun in its journey through the stellar system

  2. b)

    The short-period comets mostly move in direct elliptic orbits of small inclination (i≈15°) Whose aphelia lie near the path of one of the lame planets. The cometary families of Jupiter, Saturn,.. evidently result from the capture of long-period comets. Since in the course of time such comets are dissipated by breaking-up and evaporation of their material, the swarm of short-period comets must be continually replenished by further captures.



Solar Wind Cometary Tail Iron Meteorite Interplanetary Dust Retrograde Motion 
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Comets, Meteors and Meteorites, Interplanetary Dust; Structure and Composition

  1. Hawkins, G. S.: Meteors, comets and meteorites. New York-San FranciscoToronto-London: McGraw-Hill 1964.Google Scholar
  2. Lovell, A. C. B.: Meteor astronomy. Oxford: Clarendon Press 1954.Google Scholar
  3. Richter, N. B.: The nature of comets (English translation). London: Methuen 1963.Google Scholar
  4. La physique des comètes,Col. Internat. d’Astrophysique Liège 1952.Google Scholar

Copyright information

© Springer-Verlag New York Inc. 1969

Authors and Affiliations

  • Albrecht Unsöld
    • 1
  1. 1.Institute for Theoretical Physics and University ObservatoryKielGermany

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