Round craters seem to indicate a 90 degree impact from a meteor... But meteors should come from all directions, shouldn't there be some elliptical craters and some trenches dug ending in essentially half craters.

  • $\begingroup$ The Imbrium impactor hit the moon at about 30 degree angle: news.brown.edu/articles/2016/07/imbrium $\endgroup$ – Count Iblis Mar 16 '17 at 2:34
  • $\begingroup$ Thanks for that info!, but I could rephrase the question to why are there so many apparent 90 degree impacts on the Moon... But your comment is helpful. $\endgroup$ – scm Mar 16 '17 at 2:46
  • $\begingroup$ Your basic problem starts right at the beginning: "Round craters seem to indicate a 90 degree impact from a meteor". You can test this with a metal baking dish full of flour or something similar. But do it outside 'cause it's kind of messy. Short-short version: round craters result from all the angles that you can generate that way. $\endgroup$ – dmckee Mar 16 '17 at 2:56
  • $\begingroup$ Ok that's testable... but you seem to be saying coming in at a grazing angle would leave a round crater.. no trench leading up to the crater... see this earth impact en.wikipedia.org/wiki/List_of_impact_craters_on_Earth#/media/… Where it looks like the meteor or whatever hit at an angle. $\endgroup$ – scm Mar 16 '17 at 3:03
  • $\begingroup$ Neil deGrasse Tyson addresses this here (1:49:52 in case it doesn't open to the right time for some reason). A quick summary is that if a projectile has more kinetic energy than the energy binding it together, the impact will cause the projectile itself to explode spherically. $\endgroup$ – Edmund Witkowski Mar 16 '17 at 3:13

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