[meteorite-list] Fireballs & Known Meteor Showers

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Fri, 16 Apr 2010 15:17:59 -0500
Message-ID: <A5D1E84CA1B74BC1AB1868D36658A99B_at_ATARIENGINE2>

Carl, List,

> how we know with certainty that the WI fall is not
> related to the known shower of the same time period?

The Wisconsin Stone is a probable H5. The source
of the Lyrid meteor shower is Comet Thatcher (C/1861 G1).
I doubt that Comet Thatcher is an H5 condrite body.
It sure don't act like one...

"Certainty" is a tricky term. I've never been to Comet
Thatcher and drilled into it, so I can't swear you out
an affidavit that it isn't an H5 body, but the claim that
it is would be extraordinary.

And extraordinary claims require extraordinary proof,
as another guy named Carl used to say...


Sterling K. Webb
---------------------------------------------------------------------

----- Original Message -----
From: <cdtucson at cox.net>
To: "Jeff Kuyken" <info at meteorites.com.au>; <lebofsky at lpl.arizona.edu>
Cc: <meteorite-list at meteoritecentral.com>; <geozay at aol.com>
Sent: Friday, April 16, 2010 2:08 PM
Subject: Re: [meteorite-list] Fireballs & Known Meteor Showers


> Larry,
> All due respect here but according to Norton and Chitwood's "Field
> Guide To Meteors And Meteorites". A quick review of pages 9-15 at
> least leaves open the possibility that Comet material may indeed land
> on earth.
> In addition you say;
> "Jeff, it was way before the Stardust mission that scientists gave up
> the
>> idea that CIs had anything to do with comets."
> The question is. How do they feel now? After the Stardust Mission?
> According to these pages they did find all sorts of stuff already
> known in meteorites. Including nanodiamonds, forsterite, Carbon,
> magnetite, Kamacite, cohinite, Chromite and most notably Brownleeite ,
> a new manganese silicate material. Brownleeite being essentially a
> metal there is no reason to believe it would not survive the trip
> through our atmosphere on it's own especially if it were a bigger
> chunk from the interior of a Comet that had been blasted by a meteor
> or oid. .
> And since we also do find remnants of Comets as IDP's on the ocean
> floor in the form of magnetic spherules it seem clear that Swindles
> findings may need to be updated? Again asked respectfully.
> Another possibility is that Cometary remnants could ride 'piggy back'
> with an asteroidal meteorites in much the same way they do in all
> swarm type falls.
> Carancas for example fell as a swarm of material , not just one
> single rock . This was noted and explained by the fact that a few of
> the meteorites were covered completely with fusion crust and yet still
> landed in the same general area as the main meteorite. Had they not
> ridden 'piggy back' and been protected by the big one they certainly
> would not have landed anywhere near the big one. This might mean that
> other smaller Cometary (fragile) material could land on Earth in much
> the same way. Riding behind and therefore protected by bigger pieces.
> So, I too would like to know how we know with certainty that the WI
> fall is not related to the known shower of the same time period?
> Thanks,
> Carl
>
> --
> Carl or Debbie Esparza
> Meteoritemax
>
>
> ---- lebofsky at lpl.arizona.edu wrote:
>> Hi All:
>>
>> My impression (I too need to do some more research) is that at least
>> infrared observations of Stardust particles imply that they are
>> similar to
>> (at least in one this respect) to IDPs (Interplanetary Dust
>> Particles) and
>> are anhydrous silicates. The implication being that comets (a least
>> the
>> dust theat comes of from them) are made up of silicates and ices, but
>> that
>> the comet (surfaces) have never been warm enough for the ice to have
>> melted and reacted with the silicates in order to form hydrated
>> silicates
>> (as seen on the surfaces of many asteroids and is the case with CIs).
>>
>> Jeff, it was way before the Stardust mission that scientists gave up
>> the
>> idea that CIs had anything to do with comets. It takes water to get
>> CIs
>> and at least on the surfaces of comets (and in Stardust, IDPs, and
>> probably from Deep Impact) there is no indication of hydrated
>> cometary
>> silicates (interiors are another issue).
>>
>> Tagish Lake (again I need to update and reread papers) is a C2 and is
>> essentially unaltered, as would be expected for cometary material.
>>
>> Swindle and Campins did an artlcle on the comet/meteorite connection
>> in
>> Meteorite magazine in 2006. They conclude that cometary material may
>> just
>> be too fragile to survive, though a few clasts in meteorites may be
>> of
>> cometary origin.
>>
>> Tagish Lake is C2 (and is clearly less altered than CIs (C1) and is a
>> better candidate for a comet. I must admit I do not know about a
>> possible
>> CH/CB connection (I need to ask the right people).
>>
>> Larry
>>
>> > I believe I heard that the original theory of the CI chondrites
>> > having a
>> > likely comet origin was altered after the Stardust mission. I think
>> > they
>> > found that the closest match was actually the CH/CB chondrite
>> > group. I
>> > would
>> > need to do a bit more research and see how true that is though. Or
>> > maybe
>> > someone on list has looked at some more recent work on that
>> > mission?
>> >
>> > Cheers,
>> >
>> > Jeff
>> >
>> >
>> > ----- Original Message -----
>> > From: "Greg Stanley" <stanleygregr at hotmail.com>
>> > To: <geozay at aol.com>; <meteorite-list at meteoritecentral.com>
>> > Sent: Friday, April 16, 2010 7:48 AM
>> > Subject: Re: [meteorite-list] Fireballs & Known Meteor Showers
>> >
>> >
>> >
>> > List:
>> >
>> > Has a meteorite "fall" ever been attributed to a comet? If so, do
>> > they
>> > know
>> > which one? I remember reading that Tagish Lake may be.
>> >
>> > Greg S.
>> >
>> > ----------------------------------------
>> >> From: GeoZay at aol.com
>> >> Date: Thu, 15 Apr 2010 17:44:27 -0400
>> >> To: meteorite-list at meteoritecentral.com
>> >> Subject: Re: [meteorite-list] Fireballs & Known Meteor Showers
>> >>
>> >>>>Of course they're not related, as the fireballs are from the
>> >>>>asteroid
>> >> belt
>> >> and the meteor showers are from the tails of comets.<<
>> >>
>> >> Fireballs are produced by both asteroids and comets. So far meteor
>> >> showers
>> >> are related to comets.
>> >> GeoZay
>> >>
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>> > calendars with
>> > Hotmail.
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Received on Fri 16 Apr 2010 04:17:59 PM PDT