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

They are sending the exhaust gasses out of the nozzle at extremely high speed. You know how if you jump out of a small boat, you push the boat the opposite direction of your jump? The same phenomena is happening here, just in a continuous manner as fuel is combusted and pushed overboard.

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