Hi Larry, list - Ahem. Hourse manure, as Bess Truman taught Harry to say.
Under the strains of traversing the plane of our solar system, a comet can fragment into fragemnts, as they are technically known, or cometissimals, to put it more properly. Comet Schwassmann Wachmann 3 did this quite recently, only a few months back, and Comet Encke did it not so long ago, a few millenia back. These cometissimals have ranged in size up from around 50 m or so up to the size of full comets, for cometissimals from well condensed old large comets. These cometissimals have impacted the Earth in mass, and in historic times, as at Cheimgau, for one example. They usually accompany meteor streams. While this fragmentation process is not discussed in depth in my book, Man and Impact in the Americas, available through amazon.com., you should buy yourself a copy of it anyway. good hunting, EP --- Larry Lebofsky <[EMAIL PROTECTED]> wrote: > > Hi Darren: > > This one I think I can answer and not get into > trouble with anyone in the > astronomy field. > > Meteor shower: > > Usually related to a comet (or sometimes asteroid; > extinct comet??) or > sometimes not (comet long gone). Comets have tails. > This material is small > (look at Stardust) and spreads out along the orbit > of the comet. Since this is > long (all the way around the orbit) and fairly > broad, we pass through it each > year (sometimes we go through thicker regions and > get meteor storms). This is > a meteor shower and these are named after the region > of the sky where we see > the majority "come form." There is no documented > fall from a meteor shower > (stuff too small, so fragile?). > > Comet shower: > > Humans probably have never witnessed one. This is > one of the theories for mass > extinctions on Earth. A "thing" (passing star or > planet X) plows through (or > comes close) to the Oort cloud. Lots of objects are > perturbed out of their > orbits and some now have new orbits that bring them > in close to the Sun (and > the Earth). Since there are lots of them and have > different orbits, they come > through the inner Solar System over long periods of > time. If the thing that > does the perturbing is also in orbit around the Sun, > the perturbing can happen > periodically (periodicity of extinctions). > > While we see showers regularly and can associate > them with certain comets and > at soom level predict when there will be more or > less (a little better than > reading tea leaves), this is a real thing. Not so > for comet showers. No > evidence for "Planet X," far different than the > on-going discussion. No > evidence for extinctions being periodic or over a > period of time (many people > still claim there is a periodicity, but them more > people will disclaim it). > Still not solid proof and no bit object ever seen > (though who know for sure). > > I hope this answers your question, Darren. The only > controversy is whether or > not comet showers have ever happened and if so, what > caused them. So far there > is little evidence for there ever having been one > (after the Late Heavy > Bombardment 4 billion years ago). > > LArry > > Quoting Darren Garrison <[EMAIL PROTECTED]>: > > > Okay, this explanation of "meteor shower" vs. > "comet shower" surpasses the > > new > > definition of planet to win Weird Science > Defintion of the Week. > > > > Is it just me, or would a better answer have been > to explain how meteor > > showers > > ARE produced by the debris of comets (which is > where the question seemed to > > be > > leading) and not to interpret the question as > being "do lots of comets hit > > the > > Earth at once"? > > > > > http://www.earthsky.org/shows/listenerquestions.php?date=20040417 > > ______________________________________________ > > Meteorite-list mailing list > > Meteorite-list@meteoritecentral.com > > > http://six.pairlist.net/mailman/listinfo/meteorite-list > > > > > ______________________________________________ > Meteorite-list mailing list > Meteorite-list@meteoritecentral.com > http://six.pairlist.net/mailman/listinfo/meteorite-list > __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com ______________________________________________ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
