is there no gravity in outer space?

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NewTime
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25 Dec 2016, 3:35 pm

i've heard people say that there is no gravity in outer space. if that's the case, just how do the spacecraft stay in orbit?



redrobin62
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naturalplastic
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25 Dec 2016, 5:12 pm

Someone got "weight" and "gravity" confused when they were talking to you.

If you travel in space then you will be weightless in your space craft while in transit between planets.

But that doesn't mean that "there is no gravity in space".

Astronauts in capsules in orbit around the earth are weightless, but they ,and their craft, are held in orbit by the earth's gravity.

Likewise we are not aware of the Sun pulling on us here on earth but the earth is also locked in orbit around the Sun by the Sun's gravity.

Essentially to be in orbit means to be in free fall. Imagine you are in an elevator. The elevator is in a shaft that goes to the center of the earth. The cable snaps and your elevator car falls to the center of the earth. The whole time you are falling: you,other passengers, your briefcase, and any loose objects would be floating around the car just like you are with John Glenn in a mercury space capsule. The only difference between you and the space capsule is that the capsule is falling in a longer and more curved trajectory that never hits bottom (a circular orbit).



Last edited by naturalplastic on 25 Dec 2016, 6:02 pm, edited 1 time in total.

Dave_T
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25 Dec 2016, 5:12 pm

There is gravity in outer space, whoever you are talking to are talking total BS.


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NewTime
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25 Dec 2016, 5:49 pm

Dave_T wrote:
There is gravity in outer space, whoever you are talking to are talking total BS.


i wouldn't say BS (that's a pretty strong expression), more like a misconception. if they were truly no gravity in outer space, nothing would stay in orbit.



Brainfre3ze_93
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26 Dec 2016, 8:48 am

NewTime wrote:
Dave_T wrote:
There is gravity in outer space, whoever you are talking to are talking total BS.


i wouldn't say BS (that's a pretty strong expression), more like a misconception. if they were truly no gravity in outer space, nothing would stay in orbit.


^ this


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26 Dec 2016, 8:19 pm

naturalplastic wrote:
Essentially to be in orbit means to be in free fall. Imagine you are in an elevator. The elevator is in a shaft that goes to the center of the earth. The cable snaps and your elevator car falls to the center of the earth. The whole time you are falling: you,other passengers, your briefcase, and any loose objects would be floating around the car just like you are with John Glenn in a mercury space capsule. The only difference between you and the space capsule is that the capsule is falling in a longer and more curved trajectory that never hits bottom (a circular orbit).


Correct. They call it apparent weightlessness. At 200 miles up in low Earth orbit, gravity is about the same as on the surface.



cathylynn
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26 Dec 2016, 8:36 pm

the gravitational pull of an object decreases by the square of the distance from that object.



starkid
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27 Dec 2016, 1:31 am

OP, there is gravity in outer space, but the force of gravity weakens with distance, so the force will be effectively zero (have very little effect) if a body is isolated enough from other objects.

naturalplastic wrote:
Someone got "weight" and "gravity" confused when they were talking to you.

If you travel in space then you will be weightless in your space craft while in transit between planets.


For the OP's sake, it bears stating that literal weightlessness does not exist according to contemporary physical theory. Everything in the universe weighs something at all times, though that weight may not feel like much.