Abstract
IN so many fields of astrophysics the textbooks and the ordinary review articles have a tendency to present only the ‘generally accepted’ point of view, often not mentioning alternative theories, and even sweeping under the rug those observational facts which are adverse to the dominant view. This also applies to the theory of comets. As the arrival of Comet Kohoutek, and also the space missions to comets which are now being planned, is focusing the interest on comets, we may have unique opportunities in the near future to clarify which views are correct. This calls for a survey of the controversial points. A partial list of these, with which we will be concerning ourselves here, is the following: (1) What is the physical nature of the cometary nucleus? (a) Does it invariably consist of a single monolith ? or (b) could it, in some instances at least, constitute a bunch of particles having no physical coherence ? (2) What is the genetic relationship between comets and the meteor streams with which they are associated ? (a) Do the stream meteoroids invariably derive from the associated comets ? or (b) is the reverse process also possible ? (3) Is there a net dissipation or accretion during the lifetime of a comet ? (4) What is the origin of short-period comets ? (5) What is the origin of long-period comets ? Several other questions with regard to the chemical composition of the nucleus, the mechanisms for the production of the observed radicals and ions, and the nature of the comet solarwind interaction merit discussion but are outside the scope of this letter.
This is a preview of subscription content, access via your institution
Access options
Subscribe to this journal
Receive 51 print issues and online access
$199.00 per year
only $3.90 per issue
Buy this article
- Purchase on Springer Link
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
References
Baxter, D., and Thompson, W. B., Proc. Twelfth Coll., IAU, Tucson (March 1971).
Baxter, D., and Thompson, W. B., Astrophys. J. (in the press).
Verniani, F., Smithsonian Contrib. Astrophys., 10, 181 (1967).
Kresak, L., IAU Symposium 33, Physics and Dynamics of Meteors (Springer-Verlag, New York, 1968).
Mendis, D. A., Astrophys. Space Sci., 20, 165 (1973).
Alfvén, H., and Arrhenius, G., Astrophys. Space Sci., 9, 3 (1970).
Trulsen, J., Proc. Twelfth Coll., IAU, Tucson (March 1971).
Richter, N. B., The Nature of Comets (Methuen, London, 1963).
Lyttleton, R. A., The Comets and their Origin (Cambridge University Press, 1953).
Mrkos, A., Proc. Twenty-first Nobel Symposium Saltsjobaden (September 1971).
Vsekhesviatsky, S. K., Physical Characteristics of Comets, Moscow, 1958 (U.S. NASA Tech. Translation F80, 1964).
Lovell, A. C. B., Meteor Astronomy (Oxford University Press, 1954).
Whipple, F., IAU Symposium 45, The Motion, Evolution of Orbits and Origin of Comets (Springer-Verlag, New York, 1972).
Alfvén, H., and Arrhenius, G., Astrophys. Space Sci., 21, 117 (1973).
Newton, H. A., Mem. natn. Acad. Sci., 6, 7 (1891).
Everhart, E., Astro. J., 74, 735 (1969).
Everhart, E., Astrophys. Lett., 10, 131 (1972).
Everhart, E., Astr. J., 78, 329 (1973).
Arrhenius, G., and Asunma, S., The Moon, 8 (in the press).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
ALFVÉN, H., MENDIS, A. Nature and Origin of Comets. Nature 246, 410–411 (1973). https://doi.org/10.1038/246410a0
Received:
Issue Date:
DOI: https://doi.org/10.1038/246410a0
This article is cited by
-
On the computation of optical properties of heterogeneous grains
Astrophysics and Space Science (1977)
-
Comets and interstellar masers
Nature (1975)
-
Behaviour of Comet Kohoutek (1973f)
Nature (1974)
Comments
By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.