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No. 100: Jul-Aug 1995

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Has jupiter flashed before?

Well, not Jupiter itself but its strange Galilean satellite Io. On July 26, 1983, Io suddenly brightened by about 50% for just under 2 minutes. The "flash" represented an emission of energy of some 1028 ergs, which is equivalent to the impact on the satellite of an ice mass 5-kilometers in diameter moving at 60 km/sec. This collision interpretation is encouraged by the 1994 impacts of cometary fragments on Jupiter proper. In the case of Io, however, there is another possibility: electrical arcing. Io's volcanoes are prodigious spewers of metallic sodium, and T. Gold has speculated that colossal arcs may occur in this conducting environment as Io cuts through Jupiter's magnetic field. (See Science Frontiers #10.

(O'Brien, Roger; "Has Jupiter Flashed Before?" British Astronomical Association, Journal, 104:6, 1994.)

Comment. Io is also noted for its erratic brightening after it emerges from Jupiter's shadow. For more on Io's so-called "post-eclipse brightening," see p. 67 in the book Science Frontiers and the catalog volume The Moon and the Planets, both described here.

From Science Frontiers #100, JUL-AUG 1995. 1995-2000 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