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No. 76: Jul-Aug 1991

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Will earth's rings return?

"In the past, the Earth had a ring system just like Saturn, Uranus and Neptune, according to a Danish astronomer. He has gone so far as to say that our planet boasted rings on 16 separate occasions in the past 2800 years.

"Kaare Rasmussen of the National Museum in Copenhagen carried out a survey of all reports of meteorite falls, fireballs and showers of shooting stars from 800 BC to 1750 AD. He then carried out a statistical analysis of the data. He discovered that there were many distinct periods of intense activity."

Rasmussen found that the active periods, during which he believes a ring existed about the earth, began with a peak of high meteoritic activity as the ring formed, as a consequence of the earth's capture of a comet or asteroid. This was typically followed by a decrease of activity indicating ring stability. Finally, the ring broke up as its particles were decelerated by the earth's upper atmosphere, leading to another peak of activity. Thus, the plot of me-teorite activity is U-shaped, as in the figure, with the bottom of the U a bit higher than the normal background. (Gribbin, John; "Will the Earth's Rings Return?" New Scientist, p. 19, April 6, 1991.)

From Science Frontiers #76, JUL-AUG 1991. 1991-2000 William R. Corliss