eli5: If space is a vacuum, how can rockets work? What are the thrusters pushing *against* if there is nothing out there?

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I’ve never really understood the physics of this. Obviously it works somehow — I’m not a moonlanding denier or anything — but my (admittedly primitive) brain continues to insist that a rocket thruster needs something to push *against* in order to work.

So what is it pushing against if space is essentially a void?

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Anonymous 0 Comments

Well rockets on earth also don’t push off of air. It’s like a controlled explosion that sends nearby objects flying away in all directions. Rocket’s design is so that this direction is forward.

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