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Mars’s mysterious elongated crater
- mikeklaas 16y agoWhy 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).
- robryan 16y agoI 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.
- jonsen 16y agoMaybe 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.
- pierre_M 16y agoActually 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.