[meteorite-list] Meteor Crater Impactor?

From: Yinan Wang <veomega_at_meteoritecentral.com>
Date: Fri, 10 Sep 2010 12:39:16 -0500
Message-ID: <AANLkTin372Ki5ebwcXUtxEXvmkbwTJ5mNgWgFjqegDzt_at_mail.gmail.com>

According to measurements using the measuring tool on google earth.

>From crater rim to crater rim:
NW rim to SE rim: 3,880 - 3,930 ft.
NE rim to SW rim: 3,860 - 3,910 ft.

I'd call that round, falling within margins of error, but I'm not
gonna argue impact angles, just going to reference below:

"One objection to the idea of an impact origin for the lunar craters
was the fact that all lunar craters are round. Astronomers assumed
that most meteorites would have struck the moon at oblique angles,
producing elongated craters. Barringer, however, had experimented by
firing rifle bullets into rocks and mud, and had discovered that a
projectile arriving at an oblique angle would nevertheless make a
round hole. In 1923, Barringer's 12-year-old son Richard published an
article in Popular Astronomy, using his father's rifle experiments to
argue for the impact origin of the lunar craters; Barringer himself
repeated the arguments a short time later in the Scientific American.

Ultimately, astronomers such as A.C. Gifford were able to demonstrate
that the force of an impact at astronomical speeds would result in the
explosion of the meteorite. Whatever the original angle of impact, the
result would be a circular crater. "

-Yinan



On Fri, Sep 10, 2010 at 12:24 PM, Meteorites USA <eric at meteoritesusa.com> wrote:
> I'm aware it "looks" more round from directly above crater. I purposefully
> captured the image from an angle to accentuate the elliptical shape of the
> bulges in the NW and SE corners of the crater.
>
> The point being, it's NOT round.
>
> Eric
>
>
>
> On 9/10/2010 10:12 AM, Yinan Wang wrote:
>>
>> The mhcmagazine picture is seen from an angle in google earth. When
>> you look at it directly overhead, it looks like this:
>>
>>
>> http://maps.google.com/?ie=UTF8&ll=35.02599,-111.022038&spn=0.021402,0.045276&t=h&z=15
>>
>> Looks pretty round to me.
>>
>> As for the little crater to the SSW, definitely man made, but not sure
>> for what use.
>>
>> -Yinan
>>
>> On Fri, Sep 10, 2010 at 4:59 AM, Meteorites USA<eric at meteoritesusa.com>
>> ?wrote:
>>
>>>
>>> Hi Sterling, Thanks for the answer, and links.
>>>
>>> Still have a question though. I'm more curious about the angle of
>>> descent.
>>> The paper mentions an angle of 45 degrees.
>>>
>>> This seems like a very "safe" guess. Are there any data, or information
>>> on
>>> the angle of descent other than in the paper you provided a link to.
>>>
>>> See this crater photo from Google Earth:
>>> http://www.mhcmagazine.com/images/crater.jpg
>>>
>>> The crater is not perfectly round as would be expected from an impactor
>>> coming in at a sharper angle.In fact the crater is more elliptical in
>>> shape.
>>> It appears as if the impactor hit at an angle quite a bit shallower than
>>> 45
>>> degrees.
>>>
>>> Is it possible the impactor came in at a shallower angle?
>>>
>>> Regards,
>>> Eric
>>>
>>>
>>> On 9/10/2010 1:34 AM, Sterling K. Webb wrote:
>>>
>>>>
>>>> Eric, List,
>>>>
>>>> That is the conclusion of the 2005 paper in "Nature" by
>>>> Melosh and Collins. Their computer models suggest it
>>>> fragmented and came in as a swarm of pieces, much
>>>> slowed by the atmosphere.
>>>>
>>>> Here's two popular articles:
>>>>
>>>>
>>>> http://news.nationalgeographic.com/news/2005/03/0310_050310_meteorcrater.html
>>>> and
>>>> http://www.astronomy.com/asy/default.aspx?c=a&id=2965
>>>>
>>>> Here's original paper:
>>>>
>>>> http://amcg.ese.ic.ac.uk/~gsc/publications/articles/download/article7.pdf
>>>>
>>>> Well, one page from Nature, Vol. 434, 10 March, 2005.
>>>>
>>>>
>>>>
>>>> Sterling K. Webb
>>>>
>>>>
>>>> ---------------------------------------------------------------------------------
>>>> ----- Original Message ----- From: "Meteorites USA"
>>>> <eric at meteoritesusa.com>
>>>> To: "Meteorite-list"<meteorite-list at meteoritecentral.com>
>>>> Sent: Thursday, September 09, 2010 10:44 AM
>>>> Subject: [meteorite-list] Meteor Crater Impactor?
>>>>
>>>>
>>>>
>>>>>
>>>>> Hi List,
>>>>>
>>>>> Can someone tell me the proposed/accepted angle of descent of the
>>>>> asteroid which formed Meteor Crater in AZ?
>>>>>
>>>>> Wikipedia has the impactor at 50 meters across, and velocity at 12.8
>>>>> km/s. Is this accurate?
>>>>>
>>>>> Eric
>>>>> ______________________________________________
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>>>>>
>>>>
>>>>
>>>
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>
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Received on Fri 10 Sep 2010 01:39:16 PM PDT