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No. 71: Sep-Oct 1990

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Two Hot Spots On Mercury

Radio telescopes can give planetary astronomers a rough idea of the temperature existing several feet below the surface of a distant planet. Scrutinizing Mercury with their big electronic "ears," they have found two spots on the plamet where the temperatures are several hundred degrees higher than in the surrounding areas. Actually, these hot spots are easy to understand; because, to a Mercurian, the sun comes to a stop in the sky over one of these points and then moves backwards to the other point 180 away. As the sun tarries over these two spots, it heats them preferentially. The strange apparent motion of the sun is due to the 3:2 ratio between Mercury's period of revolution around the sun (88 days) and its axial spin period (59.6 days). What is surprising is that the energy detected radiating from the two hot spots is all reradiated solar energy; that is, there seems to be no contribution at all from Mercury's core! If no heat is leaking out of Mercury's core, the core itself is very likely solid. If it is solid, it cannot establish convection cells and thus generate a magnetic field through dynamo action. But back in 1975, the Mariner 10 spacecraft radioed back that Mercury actually does possess a magnetic field, and a surprisingly large one at that. (Wilford, John Noble; "Theory of Mercury's Hot Poles Is Shown to Be a Fact," New York Times, June 13, 1990. Cr. J. Covey.)

Comment. Something is clearly awry. This inconsistency could mean that the dynamo theory presumed to be responsible for planetary magnetic fields is incorrect.

Reference. Mercury's anomalous magnetic field is cataloged in section AHZ in our catalog: The Moon and the Planets. To order, visit: here.

From Science Frontiers #71, SEP-OCT 1990. 1990-2000 William R. Corliss

Science Frontiers Sourcebook Project Reviewed in:


  • "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