X-Message-Number: 19280
Date: Sat, 15 Jun 2002 12:11:20 +1000
From: Damien Broderick <>
Subject: Re: craters and hasty assumptions

Message #19273
From: "George Smith" <>:

>I will give you just one simple example anyone on the planet can see.  Why
>are the overwhelming majority of "impact craters" on the moon circular?  If
>these craters were caused by impacts, why are almost 100% of them strictly
>circular?  Does every rock of any size striking the moon suddenly veer to
>the vertical to create a circular crater?
>
>Or is there an entirely different explanation for the evidence anyone can
>clearly see?

Of course there is, George, and even a child can test it. Go and make a
sand pit. Throw marbles at it from angles ranging from vertical to oblique.
At almost every trajectory, the crater is circular. 

As google said after about 10 seconds,

http://cse.ssl.berkeley.edu/AtHomeAstronomy/activity_05.html

>The results of this test are often very
>               surprising. One would normally expect the
>               crater to have an oblong shape on extremely
>               wide-angle impacts. In fact, all craters that
>               we have seen on the Moon and Earth are
>               pretty much circular. The reason is that an
>               explosion occurs on impact and the forces
>               associated with an explosion are always
>               spherically symmetrical. 

Damien Broderick

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