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No. 8: Fall 1979

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Rings of uranus: invisible and impossible?

Now that they have discovered nine rings around Uranus, astronomers are having trouble explaining them. First, if they are made up of small chunks of matter, the laws of celestial mechanics dictate that they should quickly spread out radially into much wider rings in just a decade or two. In other words, if the rings are ancient they should not have maintained their present form. Second, the rings are invisible when one would expect them to be bright like Saturn's. Yet, they reflect less light than the blackest coal dust. T.C. Van Flandern proposes that each ring is actually a single satellite, so small that we cannot see it, and that it sheds gases as it orbits. This small solid body would make the celestial mechanics people happy, and the gases would be invisible to the eye but still absorb light, making the ring of gases detectable when Uranus occults a star.

(Van Flandern, Thomas C.; "Rings of Uranus: Invisible and Impossible?" Science, 204:1076, 1979.)

Comment. An alternative explanation is that the rings are recently acquired and will soon disappear. An 1847 observation of a ring around Uranus exists, but a datum this old carries little weight. See our Catalog: The Moon and the Planets for this old sighting. This book is described here.

From Science Frontiers #8, Fall 1979. 1979-2000 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