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No. 18: Nov-Dec 1981

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Phoebe Not Locked To Saturn

When Voyager 2 passed through the Saturn system a few months ago, it snapped pictures of Phoebe, Saturn's outermost moon. Phoebe is nicely rounded, 200 kilometers in diameter, and swings around Saturn in a retrograde orbit 550 days long -- nothing anomalous so far. Phoebe, however, turns out to be the only solar-system satellite whose axial period of rotation is not about equal to its period of rotation about its parent planet. All other moons, including our own, are gravitationally "locked" so that they always point the same hemisphere at the parent planet.

(Anonymous; "Voyager's Fleeting Glimpse of Phoebe," New Scientist, 91:779, 1981.)

Comment. One inference here is that Phoebe is a relatively recent addition -- and a good-sized one -- to the Saturn system, and just hasn't been there long enough to become "locked."

From Science Frontiers #18, NOV-DEC 1981. 1981-2000 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