[meteorite-list] Experts Skeptical of Peruvian Meteorite Impact

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Fri, 21 Sep 2007 01:56:51 -0500
Message-ID: <0dea01c7fc1c$970305b0$a025e146_at_ATARIENGINE>

Hi, Eric, List,

    Any "planet" with any "atmosphere" has a cut-off
point on the lower limit of crater sizes. On the Moon
(no atmosphere), crater sizes go down, down, smaller
and smaller, until you see little 10 cm. craters and below.
    Venus, on the other hand, with a massive atmosphere,
is short of craters under 30 kilometers and the smallest
crater found with radar is over 2 kilometers. Instead of
small craters being the most common, the 2-km crater
is one of a handful. 99% of the 900 Venus craters are
over 5 kilometers.
    Mars has a very thin atmosphere, but MRO images
show a relative dearth of tiny craters that would be within
its power to resolve.
    Figures for our own planet are hard to come by,
despite our being here to count'em, because the surface
is so active. Small craters are a rarity, though.
    If the "Lake Titicaca crater" is real, you can add it
(at 13.5 meters) to your list!


Sterling K. Webb
---------------------------------------------------------------
----- Original Message -----
From: <star-bits at tx.rr.com>
To: <meteorite-list at meteoritecentral.com>
Sent: Friday, September 21, 2007 12:33 AM
Subject: Re: [meteorite-list] Experts Skeptical of Peruvian Meteorite Impact


Sterling wrote:

<And I read
his statement as saying just what you suggest, that any "small
crater forming event [is] much more likely to involve an iron
parent..." >

A few years back I put together a web page listing the craters over 10
meters in diameter and whether or not meteorites had been found. A quick
check of this page showed 15 craters with associated meteorites, 13 irons, 1
pallasite, and 1 mesosiderite. It may be that stones weather away while
irons remain, but of the 14 craters formed in the last 50,000 years 12 have
meteorites associated with them, 10 irons and the other 2. So it appears
craters greater than 10 meters are mostly formed by iron meteorites. At
least in recent history. Here is a link to the page I put together.

<http://star-bits.com/impact-craters.htm>

--
Eric Olson
7682 Firethorn Dr
Fayetteville, NC 28311
http://www.star-bits.com
---- "Sterling K. Webb" <sterling_k_webb at sbcglobal.net> wrote:
=============
> It's not impossible that the crater was left by a meteorite...
    This suggests he'd just finished saying that this was likely
NOT a meteorite crater, but it's not impossible... And I read
his statement as saying just what you suggest, that any "small
crater forming event [is] much more likely to involve an iron
parent..."
Sterling K. Webb
-------------------------------------------------------------------------
----- Original Message ----- 
From: "Chris Peterson" <clp at alumni.caltech.edu>
To: "Meteorite-list" <meteorite-list at meteoritecentral.com>
Sent: Thursday, September 20, 2007 6:45 PM
Subject: Re: [meteorite-list] Experts Skeptical of Peruvian Meteorite Impact
Maybe he meant (or said, and was misreported) that a small crater forming
event was much more likely to involve an iron parent? That might be a
reasonable statement.
Chris
________________________________
Chris L Peterson
http://www.cloudbait.com
----- Original Message ----- 
From: "Jason Utas" <meteoritekid at gmail.com>
To: "Meteorite-list" <meteorite-list at meteoritecentral.com>
Sent: Thursday, September 20, 2007 5:29 PM
Subject: Re: [meteorite-list] Experts Skeptical of Peruvian Meteorite Impact
> Hello All,
>
> This particular bit really makes me wonder about those fellows up at
> JPL...
>
>>It's not impossible that the crater was left by a meteorite, Yeomans
> said, but if so, then the impact object most likely was small, based
> on the size of the crater. It would also probably have been a metal
> meteorite, because those are the only kind of small meteorites that
> don't burn up as they plummet through Earth's atmosphere, he added.
> Small stony meteorites rarely make it to the surface.
>
> ...Does anyone else find his statement...completely wrong?  I mean -
> I'm used to such stuff coming out of reporters from god-knows-where,
> but from a JPL employee...
>
> Jason
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Received on Fri 21 Sep 2007 02:56:51 AM PDT