[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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