X-Message-Number: 19373
Date: Sat, 29 Jun 2002 12:24:57 -0700
From: Olaf Henny <>
Subject: Circular Craters
References: <>

Hi All:
I have been on a three week holiday and am only now catching up
on Cryonet (and a bunch of other things).  Thus I have only now
arrived at Cryonet #19286 and so far followed the discussion on
the shape of craters on Moon, Mars and other heavenly bodies.  -
No, guys, Claudia Schiffer, J. Lo and Halle Berry do not qualify
in this context.

George, I am not a physicist, and I believe, neither are you.  So
if one of them comes up with mathematical proof, that the craters
should be round no matter what the angle of impact, then I for
one will probably be incapable to follow the math, the physical
principles involved or the complexity of the reasoning.  So all
we have is the great defence mechanism for all who cannot grasp
the full depth of a problem: Mistrust (it works every time, just
ask any protester).  With it you can stop any expert's reasoning
dead in its tracks.

For us, who are challenged in physics, there remains only one
solution, - the experiment.  It does not have to involve climbing
a mountain and shooting a rifle (I abhor those things, their
purpose is to kill, and I cherish and respect life) as Charles has
proposed.  Just go out on a quiet day to a pond or lake and
collect a few rocks.  Then take your biggest one and toss it
steeply up into the air, so that it plunges into the water almost
vertical.  As we all expect the rings of the impact waves will
be circular.

Then take another rock and toss it with some force to enter the
water in a sharp angle, and see if the resulting impact waves are
circular or oblong.  I bet they are circular.

Then comes the part I always enjoyed as a kid:  Try to skip the
rock.  If you are lucky. You get 5 or 6 bounces.  The impact
waves, all circular, will quickly run into each other.  If I
remember correctly in all the hundreds (thousands?) of times I
tried it, there was not one, that wasn't, - at least to the degree
discernible with the naked eye.  They were more precisely
circular, than the impact craters on the Moon.  Water, after all
has more consistent density than the mix of rock, dirt and
minerals on the Moon.

Now, George, if you can come up with an experiment, which
does not result in circular impact waves, please let us know
how you did it, so that we can verify it.


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