[meteorite-list] "Comet shower"

[Larry Lebofsky]

Hi all:

I seem to get into trouble no matter what I say. Yes, I keep promising myself 
to buy the book. 

My response to Darren responded to the article he referred to which talked 
about comet showers lasting thousands of years or more. I assumed that they 
were referring to the long-held theory of a planet X or a passing star as the 
cause of showers of comets, hence, comet shower (and periodic mass 
distructions). I do not think that they were referring to the pieces of a 
single comet that had broken up and hit the Earth. I think that this is a 
fairly recent idea and which at least from an observational point of view is 
supported by SW3 (the breaking up part). I was unaware of any papers or books 
that discuss anything like Cheimgau. I will take your word for this and will 
get a copy of your book. I do not think John Lewis mentions it in his book, 
but I could be wrong. It is some time since I have read it.

Quoting "E.P. Grondine" <epgrondine at yahoo.com>:

> 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 <lebofsky at lpl.arizona.edu> 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 <cynapse at charter.net>:
> > 
> > > 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
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> > 
> > 
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