[meteorite-list] Observed lunar meteorite impacts hit 100

From: lebofsky at lpl.arizona.edu <lebofsky_at_meteoritecentral.com>
Date: Thu, 22 May 2008 04:10:59 -0700 (MST)
Message-ID: <54642.71.226.60.25.1211454659.squirrel_at_timber.lpl.arizona.edu>

Hi Mark:

It comes down to location, location, location. Where did they from? Where
did they end up after the the Solar System settled down? How did they get
here?

Add to this the fact that there are "cometary asteroids," objects in the
asteroid belt that seem to have cometary behavior.

Yes, it is not all that simple. However, as Chris points out, most shower
meteors, based on orbits and velocities, clearly come from objects that
did not originate in the asteroid belt and so are cometary in origin.
There are exceptions and those are the interesting ones!

On Thu, May 22, 2008 2:42 am, Mark Ford wrote:
>

> Good point Larry.
>
>
> But I can't understand why people are still carefully distinguishing
> between comets and Asteroids?, I think by now we can assume they are
> basically one and the same, and not some exotic different species. To me
> it's just that some rocks are more 'wet and oily' than others...
>
> I'd find it very very hard to believe there are no pieces of comet in
> our collections.
>
> Best,
> Mark Ford
>
>
>
>
>
> -----Original Message-----
> From: meteorite-list-bounces at meteoritecentral.com
> [mailto:meteorite-list-bounces at meteoritecentral.com] On Behalf Of
> lebofsky at lpl.arizona.edu Sent: 22 May 2008 03:09
> To: Chris Peterson
> Cc: meteorite-list at meteoritecentral.com
> Subject: Re: [meteorite-list] Observed lunar meteorite impacts hit 100
>
>
> Hi Chris:
>
>
> If I remember correctly (probably an old estimate) about 10% of the NEOs
> are thought to have a cometary origin.
>
> Also, many asteroids do contain volatiles (20% or more by weight), just
> not as much as your "typical" comet.
>
> Larry
>
>
> On Wed, May 21, 2008 4:14 pm, Chris Peterson wrote:
>
>> Hi Mark-
>>
>>
>>
>> There have been a few meteorites that some have speculated might be
>> related to showers. But most likely, none are.
>>
>> Nobody even really knows if asteroids and comets are all that
>>
> different,
>> other than comets containing volatiles. Recently, it has been
> suggested
>> that a few objects we consider asteroids may in fact be burned out
> comets.
>> And nobody really knows if the rocky material in comets is
>> actually fragile at all.
>>
>> The best argument against shower-origin meteorites is velocity: most
>> shower members are simply traveling too fast to avoid burning up high
> in
>> the atmosphere. The few showers that have slow components also, for
> the
>> most part, are low activity- barely above the sporadic background.
>>
>> The way I'd start a serious investigation of this would be to compare
>> fall dates and times with low velocity showers. Where you have a
> match, it
>> might be worth trying to determine if witness reports of the fireball
>> suggest a direction that is at least reasonably consistent with the
> shower
>> radiant.
>>
>> Chris
>>
>>
>>
>> *****************************************
>> Chris L Peterson
>> Cloudbait Observatory
>> http://www.cloudbait.com
>>
>>
>>
>>
>> ----- Original Message -----
>> From: "Mark Crawford" <mark at meteorites.cc>
>> To: <meteorite-list at meteoritecentral.com>
>> Sent: Wednesday, May 21, 2008 4:29 PM
>> Subject: Re: [meteorite-list] Observed lunar meteorite impacts hit 100
>>
>>
>>
>>
>>> This got me thinking... some of the lunar impacts are being
>>>
> attributed
>>> to well-known meteor showers.
>>>
>>> Are there any good candidates for (earthly) meteorites which may be
>>> part of such showers, and therefore potentially once part of the
> presumed
>>> parent body? I guess candidate criteria would be time of year and (at
>>> least rough visual) triangulation back to the radiant.
>>>
>>> Or as many/most showers are associated with comets rather than
>>> asteroids, is the material perhaps much more fragile and therefore
> less
>>> likely to reach the earth's surface?
>>>
>>> Mark
>>>
>>>
>>
>> ______________________________________________
>> http://www.meteoritecentral.com
>> Meteorite-list mailing list
>> Meteorite-list at meteoritecentral.com
>> http://six.pairlist.net/mailman/listinfo/meteorite-list
>>
>>
>>
>
>
> ______________________________________________
> http://www.meteoritecentral.com
> Meteorite-list mailing list
> Meteorite-list at meteoritecentral.com
> http://six.pairlist.net/mailman/listinfo/meteorite-list
>
>
> CONFIDENTIALITY NOTICE:
>
>
> This email and any files transmitted with it are confidential. If you are
> not the intended recipient, please notify us. Email info at ssl.gb.com. You
> should not copy or use this email or attachment(s) for any purpose nor
> disclose their contents to any other person.
>
> GENERAL STATEMENT:
>
>
> Southern Scientific Ltd's computer systems may be monitored and
> communications carried on them recorded, to secure the effective
> operation of the system and for other lawful purposes.
>
> Registered address Rectory Farm Rd, Sompting, Lancing, W Sussex BN15 0DP.
> Company No 1800317
>
>
>
> ______________________________________________
> http://www.meteoritecentral.com
> Meteorite-list mailing list
> Meteorite-list at meteoritecentral.com
> http://six.pairlist.net/mailman/listinfo/meteorite-list
>
>
Received on Thu 22 May 2008 07:10:59 AM PDT