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In the movie Gravity the two astronauts (Bullock and Clooney) are hit twice by the fast moving debris that bring havoc to their locations. I think this is a bad scientific mistake in the movie plot.

Indeed, different objects cannot travel the same orbit at different speeds. The shape of the orbit is defined by the total energy which depends essentially on velocity. So, objects that happen to be at the same point with different velocities will follow different orbits.

It is true that orbits are closed (in classical mechanics, not counting disturbing effects) so that an object will go over and over again through the same points, and the speedier objects will be again at the point where it met the slower one, but in the meantime the slower has also moved and the two won't pass through the meeting point at the same time again.

Any further meeting would occur only after a certain number of orbits, which makes way more than the mere 90 minutes claimed in the movie.

Is there a scientifically sound explanation for this?

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migrated from Oct 22 '13 at 14:07

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"What do you think" - I think it is true that gravity was scientifically inaccurate quite often in its details. So what? Is there an actual question asked here? – Christian Rau Oct 19 '13 at 14:19
This would be a better fit for or for the 'hard science' side of it, Most of the pieces would be in an elliptical orbit, and would quickly spread into a broad field, so it is quite possible the astronauts would be hit twice. I've not seen the movie, but had heard it does not let science get in the way of a good story. – Andrew Thompson Oct 19 '13 at 17:10
The director himself has admitted that the orbital mechanics in his movie are wrong. Early drafts of the movie were more faithful to reality, but they turned out too boring, so to speed things up scientific inaccuracy was introduced. – System Down Oct 20 '13 at 18:40
Waiting on Moderator comment for migration. – TylerShads Oct 21 '13 at 16:32
Its absolutely disheartening to see such a well framed question lay idle and not garner the attention it should. @Andrea Mori: I urge you to move this question to one of the above mentioned sites. And ya, don't forget to provide us with a link to it! :) Cheers! – KeyBrd Basher Oct 22 '13 at 5:39

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