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Re: Parent Bodies


-----Original Message-----
From: B. Boldman <apav8r@netunlimited.net>

>I know
>most are cometary, but apparently some are asteroids, such
>as the Geminids and asteroid 3200 Phaeton.

It depends on what you consider an "asteroid" to be. In the case of Phaeton,
it may be a defunct cometary nucleus or, alternatively, it could be a
genuine "planetary asteroid" which just happens to be in the same orbit as
the Geminids.


>1) Why are so many parent bodies unknown? Is it because they
>are long period comets, or comets perturbed perhaps by
>Jupiter or some other body?


Some showers are quite old and have been perturbed from their original
orbits, so it is not possible to link them to a comet. Some comets have died
out, and others have been ejected from the Solar System or kicked into new
orbits.


>2) Why are apparently so few asteroidal?

There is no real evidence to suggest that meteor showers are in any way
associated with asteroids.

>I would expect meteorites, and the experts say none fall during showers. (I
bet they have, but have not been found)

Meteorites do fall during meteor showers but there is no observational
evidence to link them with meteor shower radiants. Further, if meteorites
were associated with showers then we would expect an increase in the number
of falls during shower periods - this does not happen.

>3) Who has the best list of parent-shower data on the net?
>Something I can print out and tape to the wall?


Well, I wouldn't say mine is the best but you might find it useful:
www.ticetboo.demon.co.uk/meteors.htm

>It seems to me that in general meteor streams are not
>well-understood yet.


Meteor showers and meteoroid streams (there's no such thing as a "meteor
stream") are fairly well understood. Unfortunately, most people do not
understand the complexities of dust ejection and orbital dynamics. As a
result they see problems where none really exist.

I hope that helps.

Phil Bagnall
www.ticetboo.demon.co.uk



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