[meteorite-list] Cyclic meteorite streams?
From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Tue, 26 Feb 2008 17:19:01 -0600 Message-ID: <01bf01c878cd$f9564af0$b459e146_at_ATARIENGINE> Hi, E. P. Grondine wrote: > Along those lines, why are meteor showers (comet > debris stream intercepts) annual, and not cyclic on > another basis? A small fraction of comets have orbits that intersect the Earth's orbit at some specific spot. Debris from a comet tend to eventually get "spread out" all along the comet's orbit The density of the debris is thick or thin depending on how long it's been riding along in the general envelope of the cometary orbit. A location, a specific spot, on the Earth's orbit is actually a date, a time disguised as a place. Our calendar is walk around the circumference of the Earth's orbit in 24-hour steps. Pick any date -- August 11 -- and you have pinned down a roughly one-degree patch at a particular location on the Earth's orbit, like an address on a circular street. If that location is where a comet's orbit intersects the Earth's orbit there may (or may not) be debris going through the volume of the intersection at the same time the Earth is. If the debris stream is reasonably dense in that location year after year, we call it a meteor "shower." There have long been suspicions and suggestions of what you're talking about: "asteroidal streams," particularly associated with near-Earth asteroids. For a history of the evidence, scroll down to page four of this paper: http://www.lpi.usra.edu/books/AsteroidsIII/pdf/3017.pdf Sterling K. Webb -------------------------------------------------------------------------------- ----- Original Message ----- From: "E.P. Grondine" <epgrondine at yahoo.com> To: <meteorite-list at meteoritecentral.com> Sent: Tuesday, February 26, 2008 4:25 PM Subject: [meteorite-list] Cyclic meteorite streams? Hi all - This seems a good a time as any to being this topic up once again, as the ISS is given a chance of somewhere between 1 in 20 to 1 in 100 of being holed by ordinary man made space junk. While many have taken a look at annual fall patterns, I have often wondered if some meteorite falls are not instead cyclic, in other words come from intercepting recurring debris streams from asteroids? Along those lines, why are meteor showers (comet debris stream intercepts) annual, and not cyclic on another basis? E.P. Grondine Man and Impact in the Americas ____________________________________________________________________________________ Looking for last minute shopping deals? Find them fast with Yahoo! Search. http://tools.search.yahoo.com/newsearch/category.php?category=shopping ______________________________________________ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list at meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list Received on Tue 26 Feb 2008 06:19:01 PM PST |
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