<blockquote>
<p>Why doesn't the moon orbit the sun?</p>
</blockquote>
<p>It does. There are some who say the Moon orbits the Sun rather than the Earth. This is just silly as &quot;orbit&quot; is not (or should not be) an either-or proposition. The Moon orbits the Earth, and the Sun, and the Milky Way, and even larger collections of objects.</p>
<p>Restricting &quot;orbit&quot; to only mean objects whose trajectory is a closed elliptical path means <strong>nothing</strong> is orbiting something else. That two body Newtonian model is an approximation. Almost always, there are other bodies nearby that perturb the trajectory.</p>
<p>There don't even need to be other bodies that result in orbits that do not follow closed elliptical trajectories. We humans intentionally put satellites in orbit about the Earth whose orbital plane precesses due to the Earth's oblateness so as to keep those satellites in a Sun synchronous orbit.</p>
<p>And then there is general relativity, which nicely explained the previously unexplained 43 arc seconds per century precession of Mercury's orbit about the Sun. Note well: That tiny precession rate is dominated by an order of magnitude larger Newtonian precession caused by the other planets.</p>
<p>The point of the above: Using closed elliptical paths as the defining characteristic of an orbit is overly restrictive.</p>

CC BY-SA 4.0
2024-11-04T04:05:27.087Z
"Overly restrictive" is an understatement. As you have said, with that definition, nothing is ever in orbit with anything else.  That definition literally eliminates orbits from existence.
Nelson
CC BY-SA 4.0
2024-11-05T03:56:06.827Z
In fact, the moon's path around the sun is convex.
Joshua
CC BY-SA 4.0
2024-11-05T14:32:10.357Z
Isn't there some reason in the reasoning that if Earth and Sun were "magically" (in particular, non-gravitationally) pulled away from each other the Moon would stay with the Earth (I assume), not with the Sun? (I suppose this is a consequence of the Moon being in Earth's Hill sphere, see James' answer.)
Peter - Reinstate Monica
CC BY-SA 4.0
2024-11-05T16:50:59.163Z
@Peter-ReinstateMonica I tend to avoid magical explanations when dealing with science. Something making the Earth or Sun magically disappear, or magically get drawn apart--that's magic! Magic inherently involves supernatural processes, something science disdains.
David Hammen
CC BY-SA 4.0
2024-11-05T17:19:10.547Z
@DavidHammen Point taken. OK, I attach a rope and pull, or install a gazillion thrusters on Earth ("what if we add more power?"). The Moon will follow the Earth (I assume), not the Sun.
Peter - Reinstate Monica
CC BY-SA 4.0
2024-11-06T14:13:49.207Z
@Peter-ReinstateMonica Depends on the trajectory. If you pull the Earth away slowly (timescale>>(1 month)), the Moon will follow the Earth. If you pull the Earth away quickly (timescale<<(1 month)), you'll leave the Moon behind. In between, the messy details matter.
John Doty
CC BY-SA 4.0
2024-11-06T14:42:58.340Z
@JohnDoty The Moon will leave Earth even in the absence of the Sun though above a certain acceleration of Earth.
Peter - Reinstate Monica
CC BY-SA 4.0
2024-11-06T15:15:43.347Z
@Peter-ReinstateMonica Indeed. But the messy details are messier if the Sun is present.
John Doty
CC BY-SA 4.0
2024-11-02T12:52:12.093Z
2024-11-02T13:21:06.393Z
2024-11-02T13:21:06.393Z
David Hammen
<p>This is best not answered in any attempt to make a vaguely defined word narrowly defined.</p>
<p>The moon has a trajectory. That trajectory depends on the gravitational field which is mostly determined by the Earth and the Sun, but also Jupiter, Venus and the other planets, and every other mass in the universe.</p>
<p>That trajectory might be described as an orbit, from the frame of the Earth. In some vague way, you might also say it orbits the sun, but because the Earth orbits the sun, and the moon orbits Earth, you might say it does not orbit the sun. Nobody is going to litigate this, there's no need for a legalistic definition. Is a tomato a vegetable or a fruit?</p>
<p>Now it would be possible to craft some definition, probably along the lines of &quot;a gravitational trajectory that remains within the Hill sphere of a body, and such that there is no smaller Hill sphere which the body also remains in&quot;.  So the Moon remains in the Hill sphere of the Sun, but it doesn't orbit the sun because it also remains in the Hill sphere of the Earth.  But such efforts merely add a pseudo-scientific spin on words that we are able to use rather loosely without doing any great harm.  I'm happy to talk about &quot;parabolic orbits&quot;, for example, or &quot;the orbit of the moon around the sun&quot;, (whereas I probably could have said &quot;Trajectory&quot; in  both cases)</p>

CC BY-SA 4.0
2024-11-02T20:40:15.377Z
*"Is a tomato a vegetable or a fruit?"* It's a fruit.
Valorum
CC BY-SA 4.0
2024-11-02T21:18:13.230Z
@Valorum What about a strawberry?
James K
CC BY-SA 4.0
2024-11-02T21:24:45.330Z
It's not a vegetable.
Valorum
CC BY-SA 4.0
2024-11-02T22:16:11.320Z
(in case anyone else doesn't get the point... The fruits of the strawberry plant are the small hard black objects that you see on the surface of the sweet and swollen receptacle that is commonly called a "strawberry" (although it isn't a berry, it isn't a fruit, and it isn't made of straw)  As an edible part of a plant, the red "strawberry" could be called a vegetable.  But the point of this is that prescriptive, pseudo-scientific definitions of perfectly good words often only confuse and muddle.  So whether a tomato is a fruit of a vegetable *depends on the context*.
James K
CC BY-SA 4.0
2024-11-03T01:58:02.613Z
@JamesK All fruits are edible parts of a plant, and there therefore vegetables. The term "fruit" is generally referred to sweet, fleshy material that seeds are attached to to entice animal to engage in behavior that will disperse the seeds. I don't see how a strawberry is not a fruit.
Acccumulation
CC BY-SA 4.0
2024-11-03T12:26:28.590Z
@valorum in the culinary world, it's a vegetable and in fact is legally defined as such in Nix v. Hedden . If you attempt to call it a fruit when you import it, you will be fined. The botanical definition is simply not the only ones that matters.
eps
CC BY-SA 4.0
2024-11-03T12:33:26.753Z
It does make the analogy in this answer kinda funny, because in the case of tomatoes there actually was the need for a legalistic distinction when it came to import tariffs, and the supreme Court case was actually very important and influential when it came to future cases where definitions between different domains were contradictory.
eps
CC BY-SA 4.0
2024-11-03T22:03:33.127Z
Knowledge is knowing that a tomato is a fruit. Wisdom is knowing not to put it in your fruit salad.
Peter Kirkpatrick
CC BY-SA 4.0
2024-11-04T09:15:02.507Z
@Valorum The US Department of Agriculture categorizes strawberries as fruits (they are not; they are pseudocarps, or false fruits), tomatoes and acorn squash as vegetables (they are fruits), and mushrooms as vegetables (fungi are not even plants). Botanists don't have a "vegetable" concept; that is a culinary and legal concept. Botanists most certainly do have a concept of what a fruit is -- and that includes tomatoes but excludes strawberries.
David Hammen
CC BY-SA 4.0
2024-11-04T10:44:32.000Z
What, then, is a Cashew Nut ? :-)
Russell McMahon
CC BY-SA 4.0
2024-11-04T19:23:19.593Z
Which is all to say that the moon orbits strawberries and tomatoes orbit the sun.
JimmyJames
CC BY-SA 4.0
2024-11-05T12:57:31.927Z
@David Hammen I would suggest that any definition of fruit that includes tomatoes but not strawberries is so far from the common usage of the word that it shouldn't be used in day-to-day speech without a note that you are using an irregular definition ("botanical fruit").
joelw
CC BY-SA 4.0
2024-11-05T21:44:14.490Z
@joelw and others: we are getting far off-topic in this comment thread.
David Hammen
CC BY-SA 4.0
2024-11-01T22:37:30.373Z
2024-11-01T22:37:30.373Z
James K
<p>The gravity hierarchy is <a href="https://en.wikipedia.org/wiki/Transitive_relation" rel="noreferrer">transitive</a>: everything that orbits the Earth also orbits the Sun. And if we calculate the two-body approximation of Earth's orbit around the Sun, we should include Moon's mass as part of Earth.</p>
<p>Similarly when we say that our solar system orbits around the center of the Milky Way galaxy, we mean that everything in the solar system does so.</p>
<p>How the orbit looks in drawings is determined primarily on the frame of reference chosen.
From the <a href="https://gravitysimulator.org/solar-system/the-sun-earth-and-moon-system" rel="noreferrer">Gravity simulator</a>:</p>
<p><a href="https://i.sstatic.net/M69J1Ktp.png" rel="noreferrer"><img src="https://i.sstatic.net/M69J1Ktp.png" alt="Moon and Earth orbits" /></a></p>
<p>This image is in Sun reference frame, and at this scale it looks like Moon barely wiggles around the Earth's orbit, and that they both primarily orbit the Sun. Similarly if we drew it in the galactic scale, any orbits in our solar system would appear like insignificant perturbations.</p>

CC BY-SA 4.0
2024-11-04T18:28:22.917Z
2024-11-04T18:28:22.917Z
jpa
<p>It's a good question.</p>
<p>I try to use &quot;gravitationally bound to&quot; in place of &quot;orbits&quot; whenever possible to avoid the ambiguity that comes with how different people and different contexts <em>embue</em> the word &quot;orbit&quot; with various meanings and definitions.</p>
<p>If forced, I go with</p>
<blockquote>
<p>It does orbit the Sun.</p>
</blockquote>
<p>and accompany that with</p>
<blockquote>
<p>And it would continue to orbit the Sun if the Earth suddenly disappeared because it not only circles the Sun, but it's gravitationally bound to it as well. But in everyday speech, for hierarchical multi-body systems like the Sun/Earth/Moon, we usually name the closest body as what it orbits in order to create an image or understanding of the hierarchy. After all, with gravity, everything pulls on everything, so simple adjectives that have multiple dictionary definitions often leave a lot to be desired.</p>
<p>Take &quot;light&quot; for example. Radio astronomers and X-ray astronomers can often be heard referring to their bit of the electromagnetic spectrum as &quot;light&quot; without argument.</p>
</blockquote>
<p>This is why folks mostly gave up on Mathematics and formal Logic for machine-based natural language understanding. Language is a mess!</p>
<p>So keep your head down and stick to Math. <a href="https://writing.stackexchange.com/q/62218/48332">Delete the people, keep the math and jazz.</a></p>

CC BY-SA 4.0
2024-11-03T05:23:24.350Z
2024-11-03T05:23:24.350Z
uhoh
<p>Just as we say that Paris is in France, which is in Europe, which is on the Earth, so, we do not usually say Paris, a city on the Earth, we say, Paris, a city in France. Likewise, we could say that the moon orbits the Milky Way, but since the Earth governs the Moon’s motion with some perturbations by the Sun and planets, the Earth and Moon system orbits the solar system barycenter, and that orbits the Milky Way barycenter, we say that the Moon orbits the Earth, which orbits the Sun, which orbits the Milky Way, to keep it simple.</p>

CC BY-SA 4.0
2024-11-04T00:49:58.857Z
2024-11-04T00:49:58.857Z
Pogo
<p>I suspect that the actual issue is what communicates the most useful information. Squares are, by definition, rectangular, and therefore <em>could</em> be called rectangles, but it's more useful to call them squares, because that commmunicates everything calling them rectangles communicates, and more.  The moon goes around the sun, but it's far more useful to specify that it goes around the Earth, and it's implicit in the narrower definition that it also, by extension, goes around the sun.  So we naturally specify the moon orbits the Earth.</p>

CC BY-SA 4.0
2024-11-03T17:40:25.917Z
2024-11-03T17:40:25.917Z
Jedediah
<p>I think it depends on context. If someone asks you whether the Hubble Telescope is orbiting the earth or the sun, you <em>can</em> say, &quot;well, technically, it's orbiting both&quot;, but it will be more helpful to them if you just say it's orbiting the earth. Still, it is absolutely true that it's orbiting both.</p>

CC BY-SA 4.0
2024-11-04T00:09:02.320Z
What about JWST? It is at a place which is gravitationally influenced by both bodies.
Paŭlo Ebermann
CC BY-SA 4.0
2024-11-04T05:43:35.863Z
I think most people would think of it as mainly a solar orbit, but it might be best to think of it as orbiting the earth/sun system. It certainly is an edge case.
Mark Foskey
CC BY-SA 4.0
2024-11-05T12:23:04.800Z
@MarkFoskey I usually argue that Lagrange/Halo orbits are strictly in heliocentric orbits, that happen to be in a 1:1 resonance with the Earth. If the Earth disappeared the JWST would continue to orbit the Sun in roughly a year in roughly a circle. But if the Sun disappeared, I'm pretty sure JWST would not be bound to the Earth and just fly off in a different direction.
uhoh
CC BY-SA 4.0
2024-11-05T13:09:26.020Z
I think you're right. I conceded too much.
Mark Foskey
CC BY-SA 4.0
2024-11-03T03:56:19.173Z
2024-11-03T03:56:19.173Z
Mark Foskey
<p>The other day, my girlfriend who is in her college's astronomy club told me a discussion was sparked in a meeting regarding what orbits really mean. She said someone tried to make an &quot;extreme&quot; argument, something like: &quot;so if an orbit just means you're going around something, the moon orbits the sun!&quot;. She didn't agree, because intuitively we don't think the moon orbits the sun; the moon orbits the Earth, which itself orbits the sun, and it goes in a hierarchy... right?</p>
<p>I'm more mathematically inclined than she is, so this made a sour taste in my mouth, and it got me thinking. Why? Why <strong>doesn't</strong> the moon orbit the sun? The path it takes is certainly not elliptic, but why doesn't it classify as an orbit? Why isn't the sum of orbits an orbit itself? Couldn't you go all out Fourier-mode and make an orbit that follows any shape you want?</p>

CC BY-SA 4.0
2024-11-02T13:10:08.417Z
As I said in https://astronomy.stackexchange.com/a/55112/16685 we get a reasonable first approximation by treating the motion of the EMB (Earth-Moon barycentre) around the Sun as a Kepler ellipse. But the orbit of the Earth and Moon about their barycentre is *not* a nice static ellipse.
PM 2Ring
CC BY-SA 4.0
2024-11-02T13:24:54.013Z
On a small screen, the Moon's solar orbit looks pretty circular. Here's a [screenshot](https://i.sstatic.net/F0J0ozJV.png) made with my 3D plotting script from https://astronomy.stackexchange.com/a/57281/16685 The plot is for last year, with a timestep of 1 day. The Moon's ID number is 301.
PM 2Ring
CC BY-SA 4.0
2024-11-02T15:12:16.260Z
The concept of an orbit is just a simplification of the n-body problem, where only two bodies are considered in the solution.  It works well in a lot of situations, breaks down in a lot of situations.  It's more important to know where it breaks down than to try to define it exactly.
Greg Miller
CC BY-SA 4.0
2024-11-02T15:13:41.797Z
@GregMiller That's kind of what I was thinking with my reference to Fourier series where you could make an "orbit" of ANY shape given an arbitrary amount of bodies and tweaking their velocities properly. At least I would think that's theoretically possible, if maybe a little silly
HydroPage
CC BY-SA 4.0
2024-11-03T14:27:57.353Z
And now for something completely different! (Monty Python) What about JWST's "halo orbit" of the Sun-Earth L2 point? It can take a while for folks like me to get their head around how JWST orbits the sun but is tugged back and forth a bit by earth's gravitational influence.
BradV
CC BY-SA 4.0
2024-11-03T16:18:51.420Z
Relevant related recent minute physics video: https://www.youtube.com/watch?v=KBcxuM-qXec&ab_channel=minutephysics
Willem Renzema
CC BY-SA 4.0
2024-11-03T20:57:15.163Z
"A orbits B" is transitive.
Sören
CC BY-SA 4.0
2024-11-04T10:46:11.053Z
To add some light hearted confusion :-) : Sol orbits the Sol-ar system barycentre which is often inside Sol but may be fully outside it.
Russell McMahon
<orbit>
Confused about what an orbit means now
HydroPage
# Confused about what an orbit means now

(Asked by: username_0 on 2024-11-01)

The other day, my girlfriend who is in her college's astronomy club told me a discussion was sparked in a meeting regarding what orbits really mean. She said someone tried to make an "extreme" argument, something like: "so if an orbit just means you're going around something, the moon orbits the sun!". She didn't agree, because intuitively we don't think the moon orbits the sun; the moon orbits the Earth, which itself orbits the sun, and it goes in a hierarchy... right?

I'm more mathematically inclined than she is, so this made a sour taste in my mouth, and it got me thinking. Why? Why **doesn't** the moon orbit the sun? The path it takes is certainly not elliptic, but why doesn't it classify as an orbit? Why isn't the sum of orbits an orbit itself? Couldn't you go all out Fourier-mode and make an orbit that follows any shape you want?

**Tags:** orbit

> **Comments:**
> **username_1**: As I said in https://astronomy.stackexchange.com/a/55112/16685 we get a reasonable first approximation by treating the motion of the EMB (Earth-Moon barycentre) around the Sun as a Kepler ellipse. But the orbit of the Earth and Moon about their barycentre is *not* a nice static ellipse.  
> **username_1**: On a small screen, the Moon's solar orbit looks pretty circular. Here's a [screenshot](https://i.sstatic.net/F0J0ozJV.png) made with my 3D plotting script from https://astronomy.stackexchange.com/a/57281/16685 The plot is for last year, with a timestep of 1 day. The Moon's ID number is 301.  
> **username_2**: The concept of an orbit is just a simplification of the n-body problem, where only two bodies are considered in the solution.  It works well in a lot of situations, breaks down in a lot of situations.  It's more important to know where it breaks down than to try to define it exactly.  
> **username_0**: @username_2 That's kind of what I was thinking with my reference to Fourier series where you could make an "orbit" of ANY shape given an arbitrary amount of bodies and tweaking their velocities properly. At least I would think that's theoretically possible, if maybe a little silly  
> **username_3**: And now for something completely different! (Monty Python) What about JWST's "halo orbit" of the Sun-Earth L2 point? It can take a while for folks like me to get their head around how JWST orbits the sun but is tugged back and forth a bit by earth's gravitational influence.  
> **username_4**: Relevant related recent minute physics video: https://www.youtube.com/watch?v=KBcxuM-qXec&ab_channel=minutephysics  
> **username_5**: "A orbits B" is transitive.  
> **username_6**: To add some light hearted confusion :-) : Sol orbits the Sol-ar system barycentre which is often inside Sol but may be fully outside it.  

---

## 7 answers

### Answer by username_7 on 2024-11-02. Score: 33

> Why doesn't the moon orbit the sun?

It does. There are some who say the Moon orbits the Sun rather than the Earth. This is just silly as "orbit" is not (or should not be) an either-or proposition. The Moon orbits the Earth, and the Sun, and the Milky Way, and even larger collections of objects.

Restricting "orbit" to only mean objects whose trajectory is a closed elliptical path means **nothing** is orbiting something else. That two body Newtonian model is an approximation. Almost always, there are other bodies nearby that perturb the trajectory.

There don't even need to be other bodies that result in orbits that do not follow closed elliptical trajectories. We humans intentionally put satellites in orbit about the Earth whose orbital plane precesses due to the Earth's oblateness so as to keep those satellites in a Sun synchronous orbit.

And then there is general relativity, which nicely explained the previously unexplained 43 arc seconds per century precession of Mercury's orbit about the Sun. Note well: That tiny precession rate is dominated by an order of magnitude larger Newtonian precession caused by the other planets.

The point of the above: Using closed elliptical paths as the defining characteristic of an orbit is overly restrictive.

> **Comments:**
> **username_8**: "Overly restrictive" is an understatement. As you have said, with that definition, nothing is ever in orbit with anything else.  That definition literally eliminates orbits from existence.  
> **username_9**: In fact, the moon's path around the sun is convex.  
> **username_10**: Isn't there some reason in the reasoning that if Earth and Sun were "magically" (in particular, non-gravitationally) pulled away from each other the Moon would stay with the Earth (I assume), not with the Sun? (I suppose this is a consequence of the Moon being in Earth's Hill sphere, see username_12' answer.)  
> **username_7**: @username_10-ReinstateMonica I tend to avoid magical explanations when dealing with science. Something making the Earth or Sun magically disappear, or magically get drawn apart--that's magic! Magic inherently involves supernatural processes, something science disdains.  
> **username_10**: @username_7 Point taken. OK, I attach a rope and pull, or install a gazillion thrusters on Earth ("what if we add more power?"). The Moon will follow the Earth (I assume), not the Sun.  
> **username_11**: @username_10-ReinstateMonica Depends on the trajectory. If you pull the Earth away slowly (timescale>>(1 month)), the Moon will follow the Earth. If you pull the Earth away quickly (timescale<<(1 month)), you'll leave the Moon behind. In between, the messy details matter.  
> **username_10**: @username_11 The Moon will leave Earth even in the absence of the Sun though above a certain acceleration of Earth.  
> **username_11**: @username_10-ReinstateMonica Indeed. But the messy details are messier if the Sun is present.  

---

### Answer by username_12 on 2024-11-01. Score: 18

This is best not answered in any attempt to make a vaguely defined word narrowly defined.

The moon has a trajectory. That trajectory depends on the gravitational field which is mostly determined by the Earth and the Sun, but also Jupiter, Venus and the other planets, and every other mass in the universe.

That trajectory might be described as an orbit, from the frame of the Earth. In some vague way, you might also say it orbits the sun, but because the Earth orbits the sun, and the moon orbits Earth, you might say it does not orbit the sun. Nobody is going to litigate this, there's no need for a legalistic definition. Is a tomato a vegetable or a fruit?

Now it would be possible to craft some definition, probably along the lines of "a gravitational trajectory that remains within the Hill sphere of a body, and such that there is no smaller Hill sphere which the body also remains in". So the Moon remains in the Hill sphere of the Sun, but it doesn't orbit the sun because it also remains in the Hill sphere of the Earth. But such efforts merely add a pseudo-scientific spin on words that we are able to use rather loosely without doing any great harm. I'm happy to talk about "parabolic orbits", for example, or "the orbit of the moon around the sun", (whereas I probably could have said "Trajectory" in both cases)

> **Comments:**
> **username_13**: *"Is a tomato a vegetable or a fruit?"* It's a fruit.  
> **username_12**: @username_13 What about a strawberry?  
> **username_13**: It's not a vegetable.  
> **username_12**: (in case anyone else doesn't get the point... The fruits of the strawberry plant are the small hard black objects that you see on the surface of the sweet and swollen receptacle that is commonly called a "strawberry" (although it isn't a berry, it isn't a fruit, and it isn't made of straw)  As an edible part of a plant, the red "strawberry" could be called a vegetable.  But the point of this is that prescriptive, pseudo-scientific definitions of perfectly good words often only confuse and muddle.  So whether a tomato is a fruit of a vegetable *depends on the context*.  
> **username_14**: @username_12 All fruits are edible parts of a plant, and there therefore vegetables. The term "fruit" is generally referred to sweet, fleshy material that seeds are attached to to entice animal to engage in behavior that will disperse the seeds. I don't see how a strawberry is not a fruit.  
> **username_15**: @username_13 in the culinary world, it's a vegetable and in fact is legally defined as such in Nix v. Hedden . If you attempt to call it a fruit when you import it, you will be fined. The botanical definition is simply not the only ones that matters.  
> **username_15**: It does make the analogy in this answer kinda funny, because in the case of tomatoes there actually was the need for a legalistic distinction when it came to import tariffs, and the supreme Court case was actually very important and influential when it came to future cases where definitions between different domains were contradictory.  
> **username_16**: Knowledge is knowing that a tomato is a fruit. Wisdom is knowing not to put it in your fruit salad.  
> **username_7**: @username_13 The US Department of Agriculture categorizes strawberries as fruits (they are not; they are pseudocarps, or false fruits), tomatoes and acorn squash as vegetables (they are fruits), and mushrooms as vegetables (fungi are not even plants). Botanists don't have a "vegetable" concept; that is a culinary and legal concept. Botanists most certainly do have a concept of what a fruit is -- and that includes tomatoes but excludes strawberries.  
> **username_6**: What, then, is a Cashew Nut ? :-)  
> **username_17**: Which is all to say that the moon orbits strawberries and tomatoes orbit the sun.  
> **username_18**: @username_7 I would suggest that any definition of fruit that includes tomatoes but not strawberries is so far from the common usage of the word that it shouldn't be used in day-to-day speech without a note that you are using an irregular definition ("botanical fruit").  
> **username_7**: @username_18 and others: we are getting far off-topic in this comment thread.  

---

### Answer by username_19 on 2024-11-04. Score: 7

The gravity hierarchy is [transitive](https://en.wikipedia.org/wiki/Transitive_relation): everything that orbits the Earth also orbits the Sun. And if we calculate the two-body approximation of Earth's orbit around the Sun, we should include Moon's mass as part of Earth.

Similarly when we say that our solar system orbits around the center of the Milky Way galaxy, we mean that everything in the solar system does so.

How the orbit looks in drawings is determined primarily on the frame of reference chosen.
From the [Gravity simulator](https://gravitysimulator.org/solar-system/the-sun-earth-and-moon-system):

[![Moon and Earth orbits](https://i.sstatic.net/M69J1Ktp.png)](https://i.sstatic.net/M69J1Ktp.png)

This image is in Sun reference frame, and at this scale it looks like Moon barely wiggles around the Earth's orbit, and that they both primarily orbit the Sun. Similarly if we drew it in the galactic scale, any orbits in our solar system would appear like insignificant perturbations.


---

### Answer by username_20 on 2024-11-03. Score: 6

It's a good question.

I try to use "gravitationally bound to" in place of "orbits" whenever possible to avoid the ambiguity that comes with how different people and different contexts *embue* the word "orbit" with various meanings and definitions.

If forced, I go with

> It does orbit the Sun.

and accompany that with

> And it would continue to orbit the Sun if the Earth suddenly disappeared because it not only circles the Sun, but it's gravitationally bound to it as well. But in everyday speech, for hierarchical multi-body systems like the Sun/Earth/Moon, we usually name the closest body as what it orbits in order to create an image or understanding of the hierarchy. After all, with gravity, everything pulls on everything, so simple adjectives that have multiple dictionary definitions often leave a lot to be desired.
>
> Take "light" for example. Radio astronomers and X-ray astronomers can often be heard referring to their bit of the electromagnetic spectrum as "light" without argument.

This is why folks mostly gave up on Mathematics and formal Logic for machine-based natural language understanding. Language is a mess!

So keep your head down and stick to Math. [Delete the people, keep the math and jazz.](https://writing.stackexchange.com/q/62218/48332)


---

### Answer by username_21 on 2024-11-04. Score: 5

Just as we say that Paris is in France, which is in Europe, which is on the Earth, so, we do not usually say Paris, a city on the Earth, we say, Paris, a city in France. Likewise, we could say that the moon orbits the Milky Way, but since the Earth governs the Moon’s motion with some perturbations by the Sun and planets, the Earth and Moon system orbits the solar system barycenter, and that orbits the Milky Way barycenter, we say that the Moon orbits the Earth, which orbits the Sun, which orbits the Milky Way, to keep it simple.


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### Answer by username_22 on 2024-11-03. Score: 3

I suspect that the actual issue is what communicates the most useful information. Squares are, by definition, rectangular, and therefore *could* be called rectangles, but it's more useful to call them squares, because that commmunicates everything calling them rectangles communicates, and more. The moon goes around the sun, but it's far more useful to specify that it goes around the Earth, and it's implicit in the narrower definition that it also, by extension, goes around the sun. So we naturally specify the moon orbits the Earth.


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### Answer by username_23 on 2024-11-03. Score: 1

I think it depends on context. If someone asks you whether the Hubble Telescope is orbiting the earth or the sun, you *can* say, "well, technically, it's orbiting both", but it will be more helpful to them if you just say it's orbiting the earth. Still, it is absolutely true that it's orbiting both.

> **Comments:**
> **username_24**: What about JWST? It is at a place which is gravitationally influenced by both bodies.  
> **username_23**: I think most people would think of it as mainly a solar orbit, but it might be best to think of it as orbiting the earth/sun system. It certainly is an edge case.  
> **username_20**: @username_23 I usually argue that Lagrange/Halo orbits are strictly in heliocentric orbits, that happen to be in a 1:1 resonance with the Earth. If the Earth disappeared the JWST would continue to orbit the Sun in roughly a year in roughly a circle. But if the Sun disappeared, I'm pretty sure JWST would not be bound to the Earth and just fly off in a different direction.  
> **username_23**: I think you're right. I conceded too much.  

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