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. Best, Olaf Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=19373