Why is this so mysterious? It looks exactly like you'd expect an oblique-angle impact would (and the article speculates that it is the most likely cause).
I assume that they are rare? I'm not sure if they are possible on a planet with a decent atmosphere like Earth to, given that things that shallow would be flung back into space.
Maybe the incoming body broke into several bodies before impact. Combined with an angle of attack wouldn't the smaller bodies down before larger bodies due to atmospheric drag.
Actually it was originally considered mysterious why almost all craters don't look like this, at least on airless bodies, since glancing-angle impacts should be, from geometric arguments, a lot more common than nearly-orthogonal ones. And yet, if you look at the moon you'll see that every crater is damn-near circular.
It turns out that the reason is that a crater-forming impact looks less like a cricket ball hitting a sandpit, and more like a nuclear bomb going off. The crater is formed by a blast wave going straight outwards, and the sideways momentum of the incoming particle is damn near irrelevant. Hence, 99% of craters are circular.
So if this is an oblique impact it's probably with something much larger and slower-moving than your average impact crater.
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[ 5.6 ms ] story [ 69.8 ms ] threadIt turns out that the reason is that a crater-forming impact looks less like a cricket ball hitting a sandpit, and more like a nuclear bomb going off. The crater is formed by a blast wave going straight outwards, and the sideways momentum of the incoming particle is damn near irrelevant. Hence, 99% of craters are circular.
So if this is an oblique impact it's probably with something much larger and slower-moving than your average impact crater.