[meteorite-list] "Comet shower"

From: Larry Lebofsky <lebofsky_at_meteoritecentral.com>
Date: Sun Aug 20 12:08:52 2006
Message-ID: <1156083189.44e86df5590c6_at_hindmost.LPL.Arizona.EDU>

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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Received on Sun 20 Aug 2006 10:13:09 AM PDT