<p>Yes, what you're describing is similar to the <a href="https://en.wikipedia.org/wiki/Planet_Nine" rel="noreferrer">Planet Nine hypothesis</a>, that eccentricities in the <a href="https://en.wikipedia.org/wiki/Extreme_trans-Neptunian_object" rel="noreferrer">Extreme trans-Neptunian objects (ETNOs)</a> can be explained by a hypothetical planet about 5-10 times larger than the Earth about 400 - 800 AU out from the Sun. For comparison, Pluto is about 30-50 AU out. Read <a href="https://iopscience.iop.org/article/10.3847/0004-6256/151/2/22" rel="noreferrer">Evidence For A Distant Giant Planet In Our Solar System</a> for more.</p>
<p>Searches have been ongoing for this hypothetical planet, but it's expected to be very, very, very faint with an apparent magnitude of 22; this is like trying to spot Pluto's moons from Earth. Data from WISE, NEOWISE, and others are being combed through to find Planet 9. <a href="https://science.nasa.gov/citizen-science/backyard-worlds-planet-9/" rel="noreferrer">Backyard Worlds: Planet 9</a> lets you join in the search for real.</p>

CC BY-SA 4.0
2024-10-13T21:06:35.180Z
I believe it is possible to find an object that is causing measurable perturbations upon what we know.  My question (though not clear) was more along the lines of a system very (very) large with objects within the sun's orbit, not affecting anything we have observed.  The question of how they got there is not really my interest, rather how big something could be, and how far, yet still in a "set" orbit around our sun.... Maybe I am just looking for the math like what's the biggest object that still could be in orbit around the sun and how far away?  Thanks for the response.
John
CC BY-SA 4.0
2024-10-13T22:22:13.070Z
@John You ask a lot of questions, including "*Could there be a large planet or conglomerate mass that orbits our sun but is beyond our current perception?*" (Yes, the Planet Nine hypothesis) Could you narrow it down and clarify?
Schwern
CC BY-SA 4.0
2024-10-14T00:35:32.977Z
@John The entire Oort cloud is hypothetical. We *assume* it exists, and that occasionally comets come from there, but we can't see it, and we can't detect any gravitational effects from Oort cloud bodies. NASA JPL have a very accurate model of the observable Solar System (which can be accessed via [Horizons](https://ssd.jpl.nasa.gov/horizons/)). That model *totally ignores* the Oort cloud. Gravity of the bodies in the far reaches of the Solar System has very little influence on the observable parts of the system.
PM 2Ring
CC BY-SA 4.0
2024-10-14T01:07:05.097Z
Ok.  How large / massive of an object could we place at the furthest reaches of the sun's gravity and have it remain in orbit?  (If we could snap our fingers, and disregarding the effects of other stars or galaxies).  How far away would that be in AU's and would the size / mass have to decrease the further it was away from the sun.  Sorry, no research here, just questions.  Again, I really thank you for your responses.
John
CC BY-SA 4.0
2024-10-14T03:17:07.450Z
@John Rather than commenting on all the answers, edit your question. Although since this question already has answers, you're probably better off asking a new and more focused question.
Schwern
CC BY-SA 4.0
2024-10-14T05:40:34.963Z
@John Please ask a new question. Don't make any edits to this question that would invalidate the existing answers.
PM 2Ring
CC BY-SA 4.0
2024-10-14T05:42:32.810Z
@John But briefly, gravity has infinite range, so if the Sun were isolated, far from other stars, there would be no limit on the distance another body could orbit it.
PM 2Ring
CC BY-SA 4.0
2024-10-13T20:24:46.043Z
2024-10-13T20:24:46.043Z
Schwern
<p>There's no actual limit to the mass of an object.  Given two bodies they will orbit each other around their common centre of mass. Of course if the second body is massive enough they at some point you'd say that the sun is orbiting it rather than the other way round.</p>
<p>And there's no real limit to distance, except eventually you get so far from the sun that the gravity of other stars starts to have a greater effect and destabilises the orbit.  But there is no reason that another star couldn't orbit the sun at a distance of several thousand AU.</p>
<p>But we know that there is no such star, because we would be able to see it.</p>
<p>There could smaller, Jupiter sized objects, but as we are actively looking for such objects and continue not to find any, it looks less and less likely.</p>
<p>An object that is very very far from the sun might not reflect much sunlight.  If it is as large as Jupiter, it should glow dimly in the infrared. We have infra-red telescopes and these have been used to find &quot;brown dwarfs&quot; which are objects that are larger than Jupiter, at much greater distance. We should be able to see a Jupiter sized body. But it would be very very difficult, depending on how far away it was. We haven't found any, probably because none exist.</p>
<p>It would be nearly impossible to detect a cold, dark object.  We know that we can see Pluto-sized and -distance objects, and have found several of them.  We don't know about Pluto-sized objects that are much further than Pluto.</p>
<p>If such bodies exist they could have satellites, in fact most distant solar-system bodies have satellites, so if such an object did exist it would be likely that it had moons.  It might be challenging to justify how a large planet was able to form in such a remote location, or how it was able to migrate to such a distance.</p>
<p>So as with most questions along the lines of &quot;does something that we can't perceive exist&quot;?  there is no definite way of saying &quot;no&quot;. On the other hand, it seems increasingly unlikely that any really big objects are out there, as we would probably have detected it already.</p>
<p>Is there an elephant in the bedroom?  No! (you'd be able to see it)  Is there a mouse? Probably not (I've been looking and can't find one, but a mouse could be hiding).  Is there a flea? I don't know.  Fleas are hard to see.  Is there a microbe? Probably, I can't see them, but I know them to be everywhere.  Likewise. Is there a very large &quot;stellar&quot; sized object in the Ooort cloud? No (you'd be able to see it)  Is there a Jupiter sized object? Probably not (We've looked and can't find one, but it could be hiding) Is there a terrestial sized object? I don't know, they'd be too hard to see.  Is there asteroid sized object? Probably, we can't see them, but we know them to be everywhere.</p>

CC BY-SA 4.0
2024-10-12T20:24:39.157Z
And Pluto is actually quite small. The mass of the entire Pluto system is under 19.9% the mass of our Moon. (Pluto itself, without its moons, is ~17.73%).
PM 2Ring
CC BY-SA 4.0
2024-10-13T09:56:16.790Z
Well, there are ongoing speculations about "planet 9, nee 10". With every observational and computational improvement, [the constraints have been narrowed](https://iopscience.iop.org/article/10.3847/1538-3881/153/3/91), but it is apparently not ruled out.
Peter - Reinstate Monica
CC BY-SA 4.0
2024-10-13T21:12:38.857Z
I believe it is possible to find an object that is causing measurable perturbations upon what we know. My question (though not clear) was more along the lines of a system very (very) large with objects within the sun's orbit, not affecting anything we have observed. The question of how they got there is not really my interest, rather how big something could be, and how far, yet still in a "set" orbit around our sun.... Maybe I am just looking for the math like what's the biggest object that still could be in orbit around the sun and how far away? Thanks for the response.
John
CC BY-SA 4.0
2024-10-13T22:09:32.187Z
@John  Well there's no actual maths here.  It's just that we've looked and not seen.  Is there an elephant in your bedroom?  Is there a mouse in your bedroom?  Is there a flea?  A microbe? You are probably pretty certain that there isn't an elephant (and we are pretty certain that there isn't a very very large body, like a "star")  You might be less certain about a mouse, but after searching for half an hour, but one could be hiding (likewise, there might be a large object if it is hiding by being far away)  You can't see microbes, but you are fairly sure that they exist! (small bodies exist)
James K
CC BY-SA 4.0
2024-10-14T01:06:37.767Z
Ok.  How large / massive of an object could we place at the furthest reaches of the sun's gravity and have it remain in orbit?  (If we could snap our fingers, and disregarding the effects of other stars or galaxies).  How far away would that be in AU's and would the size / mass have to decrease the further it was away from the sun.  Sorry, no research here, just questions.  Again, I really thank you for your responses.
John
CC BY-SA 4.0
2024-10-14T05:35:45.937Z
There's no limit on the mass. Given two masses, they will orbit around their common centre of mass.  If we disregard other stars etc, then there is no limit on the distance either.  So anything between 0 and infinity kg and anything between 0 and infinity AU.
James K
CC BY-SA 4.0
2024-10-14T18:44:00.813Z
@John To add to James K's point... what you're asking about is called a [Hill sphere](https://en.wikipedia.org/wiki/Hill_sphere?wprov=sfla1). It describes how far away from the Sun (or any body) you can go before the gravity of some neighboring body takes over. To answer your question in any meaningful way we must regard the effects of neighboring stars.
Schwern
CC BY-SA 4.0
2024-10-12T16:21:18.350Z
2024-10-14T20:04:06.337Z
2024-10-14T20:04:06.337Z
James K
<p>Obviously I am not a scholar or scientist.  Could there be a large planet or conglomerate mass that orbits our Sun but is beyond our current perception?  Could it have satellites? Might it affect objects that would be on the outside perimeter of an Oort cloud, pulling some of the particles or objects from that cloud further away from the Sun?  Or could there be extremely large objects even further away that are just outside the effects of other systems but still in an extremely distant orbit of our Sun?  Could these objects be much more massive than Jupiter and have satellites that dwarf our known planets?</p>

CC BY-SA 4.0
2024-10-12T20:30:45.853Z
"The [Oort cloud](https://en.wikipedia.org/wiki/Oort_cloud) is *theorized* to be a vast cloud of icy planetesimals surrounding the Sun at distances ranging from 2,000 to 200,000 AU (0.03 to 3.2 light-years)". That's a long way from our known planets! Neptune is ~30 AU from the Sun.
PM 2Ring
CC BY-SA 4.0
2024-10-13T22:19:57.353Z
"*Might it affect objects that would be on the outside perimeter of an "oort cloud," pulling some of the particles or objects from that "cloud" further away from the sun?*" The Oort Cloud is poorly understood and hypothesized to go up to 2000 AU to 3 ly away, at which point other stars start pulling on Oort Cloud bodies and the question of what is "within our solar system" becomes fuzzy.
Schwern
CC BY-SA 4.0
2024-10-14T06:17:14.280Z
Closely related if not duplicate of https://astronomy.stackexchange.com/questions/1179/hypothetical-trans-neptunian-planets-orbiting-the-sun see also https://astronomy.stackexchange.com/questions/13341/what-type-of-planetary-mass-object-would-planet-nine-be  https://astronomy.stackexchange.com/questions/16387/is-planet-nine-observable-in-principle https://astronomy.stackexchange.com/questions/13373/what-good-evidence-exists-for-the-9th-planet-as-spoken-of-by-caltech https://astronomy.stackexchange.com/questions/13330/why-hasnt-the-9th-planet-been-detected-already and several others...
ProfRob
CC BY-SA 4.0
2024-10-14T10:29:41.520Z
This question is similar to: [Hypothetical trans-Neptunian planets orbiting the Sun](https://astronomy.stackexchange.com/questions/1179/hypothetical-trans-neptunian-planets-orbiting-the-sun). If you believe it’s different, please [edit] the question, make it clear how it’s different and/or how the answers on that question are not helpful for your problem.
Starship
<planet><solar-system>
Could there be mini systems within our solar system, beyond what we can currently perceive?
John
# Could there be mini systems within our solar system, beyond what we can currently perceive?

(Asked by: username_0 on 2024-10-12)

Obviously I am not a scholar or scientist. Could there be a large planet or conglomerate mass that orbits our Sun but is beyond our current perception? Could it have satellites? Might it affect objects that would be on the outside perimeter of an Oort cloud, pulling some of the particles or objects from that cloud further away from the Sun? Or could there be extremely large objects even further away that are just outside the effects of other systems but still in an extremely distant orbit of our Sun? Could these objects be much more massive than Jupiter and have satellites that dwarf our known planets?

**Tags:** planet, solar-system
> **Comments:**
> **username_1**: "The [Oort cloud](https://en.wikipedia.org/wiki/Oort_cloud) is *theorized* to be a vast cloud of icy planetesimals surrounding the Sun at distances ranging from 2,000 to 200,000 AU (0.03 to 3.2 light-years)". That's a long way from our known planets! Neptune is ~30 AU from the Sun.  
> **username_2**: "*Might it affect objects that would be on the outside perimeter of an "oort cloud," pulling some of the particles or objects from that "cloud" further away from the sun?*" The Oort Cloud is poorly understood and hypothesized to go up to 2000 AU to 3 ly away, at which point other stars start pulling on Oort Cloud bodies and the question of what is "within our solar system" becomes fuzzy.  
> **username_3**: Closely related if not duplicate of https://astronomy.stackexchange.com/questions/1179/hypothetical-trans-neptunian-planets-orbiting-the-sun see also https://astronomy.stackexchange.com/questions/13341/what-type-of-planetary-mass-object-would-planet-nine-be  https://astronomy.stackexchange.com/questions/16387/is-planet-nine-observable-in-principle https://astronomy.stackexchange.com/questions/13373/what-good-evidence-exists-for-the-9th-planet-as-spoken-of-by-caltech https://astronomy.stackexchange.com/questions/13330/why-hasnt-the-9th-planet-been-detected-already and several others...  
> **username_4**: This question is similar to: [Hypothetical trans-Neptunian planets orbiting the Sun](https://astronomy.stackexchange.com/questions/1179/hypothetical-trans-neptunian-planets-orbiting-the-sun). If you believe it’s different, please [edit] the question, make it clear how it’s different and/or how the answers on that question are not helpful for your problem.  

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## 2 answers

### Answer by username_5 on 2024-10-12. Score: 17 | Accepted answer

There's no actual limit to the mass of an object. Given two bodies they will orbit each other around their common centre of mass. Of course if the second body is massive enough they at some point you'd say that the sun is orbiting it rather than the other way round.

And there's no real limit to distance, except eventually you get so far from the sun that the gravity of other stars starts to have a greater effect and destabilises the orbit. But there is no reason that another star couldn't orbit the sun at a distance of several thousand AU.

But we know that there is no such star, because we would be able to see it.

There could smaller, Jupiter sized objects, but as we are actively looking for such objects and continue not to find any, it looks less and less likely.

An object that is very very far from the sun might not reflect much sunlight. If it is as large as Jupiter, it should glow dimly in the infrared. We have infra-red telescopes and these have been used to find "brown dwarfs" which are objects that are larger than Jupiter, at much greater distance. We should be able to see a Jupiter sized body. But it would be very very difficult, depending on how far away it was. We haven't found any, probably because none exist.

It would be nearly impossible to detect a cold, dark object. We know that we can see Pluto-sized and -distance objects, and have found several of them. We don't know about Pluto-sized objects that are much further than Pluto.

If such bodies exist they could have satellites, in fact most distant solar-system bodies have satellites, so if such an object did exist it would be likely that it had moons. It might be challenging to justify how a large planet was able to form in such a remote location, or how it was able to migrate to such a distance.

So as with most questions along the lines of "does something that we can't perceive exist"? there is no definite way of saying "no". On the other hand, it seems increasingly unlikely that any really big objects are out there, as we would probably have detected it already.

Is there an elephant in the bedroom? No! (you'd be able to see it) Is there a mouse? Probably not (I've been looking and can't find one, but a mouse could be hiding). Is there a flea? I don't know. Fleas are hard to see. Is there a microbe? Probably, I can't see them, but I know them to be everywhere. Likewise. Is there a very large "stellar" sized object in the Ooort cloud? No (you'd be able to see it) Is there a Jupiter sized object? Probably not (We've looked and can't find one, but it could be hiding) Is there a terrestial sized object? I don't know, they'd be too hard to see. Is there asteroid sized object? Probably, we can't see them, but we know them to be everywhere.

> **Comments:**
> **username_1**: And Pluto is actually quite small. The mass of the entire Pluto system is under 19.9% the mass of our Moon. (Pluto itself, without its moons, is ~17.73%).  
> **username_6**: Well, there are ongoing speculations about "planet 9, nee 10". With every observational and computational improvement, [the constraints have been narrowed](https://iopscience.iop.org/article/10.3847/1538-3881/153/3/91), but it is apparently not ruled out.  
> **username_0**: I believe it is possible to find an object that is causing measurable perturbations upon what we know. My question (though not clear) was more along the lines of a system very (very) large with objects within the sun's orbit, not affecting anything we have observed. The question of how they got there is not really my interest, rather how big something could be, and how far, yet still in a "set" orbit around our sun.... Maybe I am just looking for the math like what's the biggest object that still could be in orbit around the sun and how far away? Thanks for the response.  
> **username_5**: @John  Well there's no actual maths here.  It's just that we've looked and not seen.  Is there an elephant in your bedroom?  Is there a mouse in your bedroom?  Is there a flea?  A microbe? You are probably pretty certain that there isn't an elephant (and we are pretty certain that there isn't a very very large body, like a "star")  You might be less certain about a mouse, but after searching for half an hour, but one could be hiding (likewise, there might be a large object if it is hiding by being far away)  You can't see microbes, but you are fairly sure that they exist! (small bodies exist)  
> **username_0**: Ok.  How large / massive of an object could we place at the furthest reaches of the sun's gravity and have it remain in orbit?  (If we could snap our fingers, and disregarding the effects of other stars or galaxies).  How far away would that be in AU's and would the size / mass have to decrease the further it was away from the sun.  Sorry, no research here, just questions.  Again, I really thank you for your responses.  
> **username_5**: There's no limit on the mass. Given two masses, they will orbit around their common centre of mass.  If we disregard other stars etc, then there is no limit on the distance either.  So anything between 0 and infinity kg and anything between 0 and infinity AU.  
> **username_2**: @John To add to James K's point... what you're asking about is called a [Hill sphere](https://en.wikipedia.org/wiki/Hill_sphere?wprov=sfla1). It describes how far away from the Sun (or any body) you can go before the gravity of some neighboring body takes over. To answer your question in any meaningful way we must regard the effects of neighboring stars.  

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### Answer by username_2 on 2024-10-13. Score: 5

Yes, what you're describing is similar to the [Planet Nine hypothesis](https://en.wikipedia.org/wiki/Planet_Nine), that eccentricities in the [Extreme trans-Neptunian objects (ETNOs)](https://en.wikipedia.org/wiki/Extreme_trans-Neptunian_object) can be explained by a hypothetical planet about 5-10 times larger than the Earth about 400 - 800 AU out from the Sun. For comparison, Pluto is about 30-50 AU out. Read [Evidence For A Distant Giant Planet In Our Solar System](https://iopscience.iop.org/article/10.3847/0004-6256/151/2/22) for more.

Searches have been ongoing for this hypothetical planet, but it's expected to be very, very, very faint with an apparent magnitude of 22; this is like trying to spot Pluto's moons from Earth. Data from WISE, NEOWISE, and others are being combed through to find Planet 9. [Backyard Worlds: Planet 9](https://science.nasa.gov/citizen-science/backyard-worlds-planet-9/) lets you join in the search for real.

> **Comments:**
> **username_0**: I believe it is possible to find an object that is causing measurable perturbations upon what we know.  My question (though not clear) was more along the lines of a system very (very) large with objects within the sun's orbit, not affecting anything we have observed.  The question of how they got there is not really my interest, rather how big something could be, and how far, yet still in a "set" orbit around our sun.... Maybe I am just looking for the math like what's the biggest object that still could be in orbit around the sun and how far away?  Thanks for the response.  
> **username_2**: @John You ask a lot of questions, including "*Could there be a large planet or conglomerate mass that orbits our sun but is beyond our current perception?*" (Yes, the Planet Nine hypothesis) Could you narrow it down and clarify?  
> **username_1**: @John The entire Oort cloud is hypothetical. We *assume* it exists, and that occasionally comets come from there, but we can't see it, and we can't detect any gravitational effects from Oort cloud bodies. NASA JPL have a very accurate model of the observable Solar System (which can be accessed via [Horizons](https://ssd.jpl.nasa.gov/horizons/)). That model *totally ignores* the Oort cloud. Gravity of the bodies in the far reaches of the Solar System has very little influence on the observable parts of the system.  
> **username_0**: Ok.  How large / massive of an object could we place at the furthest reaches of the sun's gravity and have it remain in orbit?  (If we could snap our fingers, and disregarding the effects of other stars or galaxies).  How far away would that be in AU's and would the size / mass have to decrease the further it was away from the sun.  Sorry, no research here, just questions.  Again, I really thank you for your responses.  
> **username_2**: @John Rather than commenting on all the answers, edit your question. Although since this question already has answers, you're probably better off asking a new and more focused question.  
> **username_1**: @John Please ask a new question. Don't make any edits to this question that would invalidate the existing answers.  
> **username_1**: @John But briefly, gravity has infinite range, so if the Sun were isolated, far from other stars, there would be no limit on the distance another body could orbit it.  

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