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No. 35: Sep-Oct 1984

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Gravity And Going Around In Ellipses

We thought that our readers might like to know that the force of gravity apparently has no significant effect on circumnutation. Now circumnutation is the result of an "impressively ubiquitous mechanism" in all elongating plant organs. More simply, it is the elliptical weaving motion seen in the tips of growing leaves, shoots, flower stalks, branch roots, etc. In a 4- to 5-day-old sunflower seedling, the ellipse traced is 6-8 millimeters long and takes about 110 minutes. The ellipses result from differ-ential growth in the elongating plants. No one knew whether the force of gravity played a role in circumnutation until some sunflower seedlings were flown on Spacelab 1. Zero-g did not affect circumnutation at all.

(Brown, Allan H. and Chapman, David K.; "Circumnutation Observed without Significant Gravitational Force in Spaceflight," Science, 225:230, 1984.)

Comment. Nature seldom indulges in frivolous actions, but we just may have a phenomenon here that has absolutely no deeper significance.

From Science Frontiers #35, SEP-OCT 1984. 1984-2000 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