[meteorite-list] Observed lunar meteorite impacts hit 100

From: Mark Ford <mark.ford_at_meteoritecentral.com>
Date: Thu, 22 May 2008 17:03:15 +0100
Message-ID: <29A9DB45B84970458190D7D39BD42C492C2836_at_gamma.ssl.atw>

Yes as I say you can label them, but I still wouldn't say the
differences where 'very distinct'.. juries still out on that one. I
wouldn't mind betting there are quite a few 'icy asteroids' out there
too...

After all:
> we know little about composition. A burned out comet may
> or may not be similar to an asteroid from a mineralogical standpoint.

Given that some moons of Saturn [may] actually be captured comets
(according to the recent Cassini findings), it strikes me that we still
have difficulty in defining exactly what is and isn't or what was or was
not 'a comet', (I guess not enough samples to define it clearly enough).

Mark my words - one day we will probably have a 'pluto style' mess
where all those things we classified/call ex-comets etc will suddenly
all be called ... ''rocks''. Lol.

Best
Mark






-----Original Message-----
From: meteorite-list-bounces at meteoritecentral.com
[mailto:meteorite-list-bounces at meteoritecentral.com] On Behalf Of Chris
Peterson
Sent: 22 May 2008 15:32
To: Meteorite-list at meteoritecentral.com
Subject: Re: [meteorite-list] Observed lunar meteorite impacts hit 100

There are clearly two very distinct populations of objects, which have
very different properties. Comets originate in the outer edge of the
Solar System, and ices account for a significant proportion of their
entire mass. Very few ever make it to the inner system, and when they
do, they can usually be identified by their high eccentricity orbits.
Asteroids are differentiated rocky or iron bodies that were formed or
trapped in orbit between Mars and Jupiter.

It is quite correct to distinguish between the two types of bodies. The
confusion comes from the likelihood that some comets have ended up in
asteroidal orbits, and have lost their volatiles. And also, that
gravitational perturbations have put some asteroids into more comet-like

orbits. It isn't that these aren't very different objects, but that in
some cases we are uncertain about an object's true classification.
Additionally, we know little about composition. A burned out comet may
or may not be similar to an asteroid from a mineralogical standpoint.

Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com


----- Original Message -----
From: "Mark Ford" <mark.ford at ssl.gb.com>
To: <Meteorite-list at meteoritecentral.com>
Sent: Thursday, May 22, 2008 3:42 AM
Subject: Re: [meteorite-list] Observed lunar meteorite impacts hit 100

> 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
-list

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Received on Thu 22 May 2008 12:03:15 PM PDT