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No. 64: Jul-Aug 1989

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Halley: a young, combusting, alien interloper

Can this be the comet Halley of the textbooks? Comets are supposed to be as old as the solar system itself (4.6 billion years), born of solar-system stuff when a gaseous cloud condensed. Above all, comets do not "burn" or combust!

The vision of a "burning" comet was advanced by recent observations that the velocity and temperature of the gases escaping from Halley are higher than one would expect from the sublimation of ices under solar radiation. Also, the concentration of expelled material in large, hypersonic jets carrying large quantities of fine dust further undermine the sublimation model.

E.M. Drobyshevski has concluded

"The new observations, together with some earlier data still poorly understood (e.g., the appearance in the coma of large amounts of C3 ) can be accounted for by assuming the cometary ices to contain, apart from the hydrocarbons, nitrogen-containing compounds, etc., also of free oxygen (about 15 wt. %). Under these conditions, burning should occur in the products of sublimation under deficiency of oxidizer accompanied by the production of 'soot,' 'smoke,' etc. The burning should propagate under the surface crust and localize at a few sites.

"The presence of oxygen in cometary ices follows from a new eruption theory assuming the minor bodies of the Solar System to have formed in explosions of the massive ice envelopes saturated with electrolysis products on distant moon-like bodies of the type of Ganymede and Callisto."

(Drobyshevski, E.M.; "Combustion as the Cause of Comet P/Halley's Activity," Earth, Moon, and Planets, 43:87, 1988. Cr. L. Ellenberger.)

Drobyshevski's combustion theory assumes a "local" origin (within the solar system) for Halley. But measurements of the ratio of carbon-12 to carbon-13, made during the 1986 flyby, produced a ratio of 65:1. This compares to 89:1 for solar system material. The 65:1 ratio, it turns out, is more typical of interstellar material. This datum seems to place Halley's birthplace somewhere outside the solar system.

(Weiss, R.; "Carbon Ratio Shows Halley May be Alien," Science News, 135:214, 1989.)

As if all this were not bad enough, calculations of the amount of matter expelled from Halley and incorporated in known meteor streams allow an estimate of Halley's residence time in the inner solar system. (One has, of course, Halley's present mass, but must estimate its original mass!) The conclusion is that Halley has spent only 23,000 years in its present orbit!

(Maddox, John; "Halley's Comet Is Quite Young," Nature, 339:95, 1989.)

Comments. Admittedly, this is a pretty shaky calculation, but it accords with the calculation that Halley had a close encounter with Jupiter about 20,000 years ago.

The manifest contradictions in the inferences made above from recent observations of Halley mean that we still have a lot to learn about comets, Halley in particular. One should also recall that the solar system has other features that may be youthful, such as Saturn's rings. (See ARL16 in our catalog: The Moon and the Planets)

For other cometary anomalies, see Chapter AC in our catalog volume: The Sun and Solar System Debris. Both catalog volumes are described here.

From Science Frontiers #64, JUL-AUG 1989. 1989-2000 William R. Corliss

Science Frontiers Sourcebook Project Reviewed in:

Quotes

  • "A sourcebook of unexplained phenomena is therefore a valuable addition to a collection of scientific literature. William R. Corliss has provided this in the past with his source books of scientific anomalies in several subjects, and now he has provided it for astronomy. He has done an excellent job of collecting and editing a large amount of material, taken in part from scientific journals and in part from scientific reporting in the popular or semi-scientific press." -- "The Mysterious Universe: A Handbook of Astronomical Anomalies", reviwed by Thomas Gold, Cornell University, in Icarus, vol.41, 1980

  • "An interesting, systematic presentation of unusual weather [..] This book is recommended for a general audience" --"Corliss, William R., Tornados, Dark Days, Anomalous Precipitation, and Related Weather Phenomena, Sourcebook Project, 1983.", revieweed in Choice, September 1983
  • "..the science is necessarily somewhat speculative, but Corliss's symthesis is based on reputable sources." -- "Corliss, William R. (Compiler). Lightning, Auroras, Nocturnal Lights, and Related Luminous Phenomena" reviwed by Joseph M. Moran, Univ. of Wisconsin in Science Books and Films, Sep/Oct 1983

  • "Before opening the book, I set certain standards that a volume which treads into dangerous grounds grounds like this must meet. The author scrupulously met, or even exceeded those standards. Each phenomenon is exhaustively documented, with references to scientific journals [..] and extensive quotations" -- "Book Review: The moon and planets: a catalog of astronomical anomalies", The Sourcebook Project, 1985., Corliss, W. R., Journal of the Royal Astronomical Society of Canada, Vol. 81, no. 1 (1987), p. 24., 02/1987