<blockquote>
  <p>What id like to know, in what distance do they have to be from each other to create only one gravitational influence.</p>
</blockquote>

<p>At whichever point you decide to call them two objects rather than one object. It's a completely arbitrary choice that depends on you rather than gravitational physics. What's going on is that gravity can be described by a mass density distribution, and which part of that distribution corresponds to "one object" and which to "another object" isn't important.</p>

<p>You may be confused by Newton's law of gravity that says the gravitational force force is proportional to the product of the masses and inversely proportional to the distance between them squared. But this law only applies to spherically symmetric objects. It only applies to you exactly if you're a <a href="https://en.wikipedia.org/wiki/Spherical_cow" rel="nofollow">spherical cow</a>.</p>

<p>This kind of arbitrariness actually applies to the Earth as well. Even if the Earth were perfectly spherically symmetric, one could say that Earth's gravity is due to the influence of the northern hemisphere <em>and</em> the influence of the southern hemisphere, etc. Whether you consider the Earth to be one object, or two, or a trillion, depends on you.</p>

<p>The Earth isn't spherically symmetric. It's closer to an oblate spheroid, since it bulges at the equator. But it isn't exactly that either, having mountains or other topographical feature, to say nothing of mass density variations <em>inside</em> the Earth. In principle, one could describe its gravity <em>including</em> people and trees or whatnot. Gravitationally, there is no fundamental difference between you and some rock. That you consider yourself to not be "part of Earth" is a choice you make for other reasons.</p>

<p>If you distance yourself from the Earth, there is a difference because the mass distribution would change. But again, whether you consider this to be "only one gravitational influence" or "the Earth plus you" is up to you, and this holds true <em>regardless</em> of whether you distanced yourself or not.</p>

CC BY-SA 3.0
2014-11-12T17:45:27.457Z
So simply put i could say that earths gravity is something like sum of all the objects that its made of and the border from which 2 objects dont act as if they were one depends only on my opinion. Thank you very much for answer. Im going to mark this one as good but feel free to add something if i understood it wrong.
Boris Bucek
CC BY-SA 3.0
2014-11-12T18:07:10.823Z
@BorisBucek That's right; e.g., one could also say that the Earth's gravity is the influence of all of its constituent atoms, etc. Although quite often, breaking up a system into parts in one way rather than another way makes things easier or even established by the kind of question being asked--if you're interested where to point your telescope for Mercury, then you're treating 'Mercury' as one object; on the other hand, there's nothing preventing you from thinking 'solar system' as one object either. How you break it up depends on what you're interested in and what you find convenient.
Stan Liou
CC BY-SA 3.0
2014-11-12T21:28:02.280Z
+1 for the spherical cow reference. . . Seriously, though, that's a good way to explain how many basic laws are only totally accurate for idealized scenarios.
HDE 226868
CC BY-SA 3.0
2014-11-12T17:04:43.737Z
2014-11-12T21:31:34.943Z
2014-11-12T21:31:34.943Z
Stan Liou
<p>Each object in the universe has its own gravitational influence on all other objects in the universe. What distance do they have to be from each other to create only one gravitational influence? Example - Every human does in my opinion contribute to the earth gravitation thanks to the mass of our bodies. Now would there be a difference if I distanced myself from the surface by any amount?</p>

CC BY-SA 3.0
2014-11-12T15:10:38.667Z
In other words, at what point does an object stop contributing to the gravity of a larger object?
Scottie
CC BY-SA 3.0
2014-11-12T15:33:08.103Z
Yes. I would really like to know this.
Boris Bucek
<gravity><earth><mass>
From what distance can one object influence gravity of another object?
Boris Bucek
# From what distance can one object influence gravity of another object?

(Asked by: username_0 on 2014-11-12)

Each object in the universe has its own gravitational influence on all other objects in the universe. What distance do they have to be from each other to create only one gravitational influence? Example - Every human does in my opinion contribute to the earth gravitation thanks to the mass of our bodies. Now would there be a difference if I distanced myself from the surface by any amount?

**Tags:** gravity, earth, mass
> **Comments:**
> **username_1**: In other words, at what point does an object stop contributing to the gravity of a larger object?  
> **username_0**: Yes. I would really like to know this.  

---

## 1 answers

### Answer by username_2 on 2014-11-12. Score: 6 | Accepted answer

> What id like to know, in what distance do they have to be from each other to create only one gravitational influence.

At whichever point you decide to call them two objects rather than one object. It's a completely arbitrary choice that depends on you rather than gravitational physics. What's going on is that gravity can be described by a mass density distribution, and which part of that distribution corresponds to "one object" and which to "another object" isn't important.

You may be confused by Newton's law of gravity that says the gravitational force force is proportional to the product of the masses and inversely proportional to the distance between them squared. But this law only applies to spherically symmetric objects. It only applies to you exactly if you're a [spherical cow](https://en.wikipedia.org/wiki/Spherical_cow).

This kind of arbitrariness actually applies to the Earth as well. Even if the Earth were perfectly spherically symmetric, one could say that Earth's gravity is due to the influence of the northern hemisphere *and* the influence of the southern hemisphere, etc. Whether you consider the Earth to be one object, or two, or a trillion, depends on you.

The Earth isn't spherically symmetric. It's closer to an oblate spheroid, since it bulges at the equator. But it isn't exactly that either, having mountains or other topographical feature, to say nothing of mass density variations *inside* the Earth. In principle, one could describe its gravity *including* people and trees or whatnot. Gravitationally, there is no fundamental difference between you and some rock. That you consider yourself to not be "part of Earth" is a choice you make for other reasons.

If you distance yourself from the Earth, there is a difference because the mass distribution would change. But again, whether you consider this to be "only one gravitational influence" or "the Earth plus you" is up to you, and this holds true *regardless* of whether you distanced yourself or not.

> **Comments:**
> **username_0**: So simply put i could say that earths gravity is something like sum of all the objects that its made of and the border from which 2 objects dont act as if they were one depends only on my opinion. Thank you very much for answer. Im going to mark this one as good but feel free to add something if i understood it wrong.  
> **username_2**: @BorisBucek That's right; e.g., one could also say that the Earth's gravity is the influence of all of its constituent atoms, etc. Although quite often, breaking up a system into parts in one way rather than another way makes things easier or even established by the kind of question being asked--if you're interested where to point your telescope for Mercury, then you're treating 'Mercury' as one object; on the other hand, there's nothing preventing you from thinking 'solar system' as one object either. How you break it up depends on what you're interested in and what you find convenient.  
> **username_3**: +1 for the spherical cow reference. . . Seriously, though, that's a good way to explain how many basic laws are only totally accurate for idealized scenarios.  

---

