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Re: (meteorobs) Excerpts from "CCNet 123/2001 - 22 November 2001"




>Riddle me this.  If all meteors from comets are very fragile dust grains,
>explain the flashes on the moon.  If, on one hand we readily accept that the
>dust trails include chucks that are large enough to generate a flash on the
>moon visable from Earth, isn't it plausible that similarly sized chunks hit
>Indiana?  Not that I would uncritically accept the story of the Yurans
>(presumably from the planet Yura), but the out-of-hand dismissal by
>astronomer Hammergren seems rash in view of the lunar observations.

Robert, the confusion may arise from your use of the words "large enough".

A "particle" (or more properly, a "composite") may be MASSIVE enough to
cause a lunar flash observable from earth, and yet still be sparse (that
is, *undense*) enough to be completely evaporated by a fiery entry into
the Earth's atmosphere at 250,000 kilometers per hour.

Keep in mind that most studies in the literature have proposed densities
for the "average" Leonid meteoroid at somewhere below 1 gm/cm3: in other
words, LESS DENSE THAN WATER! In public talks, I'll typically describe
such particles as "cosmic dustbunnies" or "celestial cottoncandy"... :)

That isn't to say that NO Leonid meteoroid could possibly be more dense:
we just have never been able to observe a "rocky Leonid" (at least, none
that this amateur is aware of!) And the statement in the article is also
true: there has never been a confirmed meteorite recovery from ANY meteor
shower, let alone from the Leonids... Again, at least none I've heard of.

This is an interesting topic - thanks for asking your question, Robert!

Clear skies all,
Lew Gramer <owner-meteorobs@atmob.org>


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