Question Is there a 9th planet? If so, then how big, dense, and massive is it? What is its orbit around the sun and gravitational effect on the Solar System?

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Does Planet 9 exist?

  • yes

  • no

  • probably

  • not sure


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When we look at other planetary systems we see worlds that are very long distance orbits from the host star.

Why not same thing here?
We could have 9th 10th 11th etc but the orbits are very distant.
Easy to see how we might have the 9th planet way out and we might never detect it unless we got very lucky and it crosses something we are looking at.

Keep an open mind is my thought :)
 
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When we look at other planetary systems we see worlds that are very long distance orbits from the host star.
Yes, some are way out there.

If you take the average distance of them all, it is greater than 25 AU because some are over 1000 AU.

But this is one of those times that an average only complicates the real picture. Here is the actual distance distribution, with the x-axis using Sol's own planetary orbits (Mercury to Neptune).



Why not same thing here?
The models can't account for such things. The formation models for the solar system, though still a work in progress, allows for billions of smaller objects to have been tossed out to form the Oort Cloud and Kuiper belt. Tossing a planet-sized object, however, would take something extra powerful not found in the models. It's not impossible, but very unlikely, apparently.
 
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Catastrophe

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Quote
Is there a 9th planet? If so, then how big, dense, and massive is it? What is its orbit around the sun and gravitational effect on the Solar System?
Quote

That is the question.

Answer: We don't know. The position is unclear. And the rest . . . . . . ? N/A = not applicable.

Cat :)
 
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Yes, some are way out there.

If you take the average distance of them all, it is greater than 25 AU because some are over 1000 AU.

But this is one of those times that an average only complicates the real picture. Here is the actual distance distribution, with the x-axis using Sol's own planetary orbits (Mercury to Neptune).




The models can't account for such things. The formation models for the solar system, though still a work in progress, allows for billions of smaller objects to have been tossed out to form the Oort Cloud and Kuiper belt. Tossing a planet-sized object, however, would take something extra powerful not found in the models. It's not impossible, but very unlikely, apparently.
For sure the odds are not great that we have a 9th planet unless it's far beyond the ort cloud.
I wouldn't bet the farm on finding a 9th but then again you never know and if it exists and is a dark body it would be a difficult thing to find.
 
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Quote
Is there a 9th planet? If so, then how big, dense, and massive is it? What is its orbit around the sun and gravitational effect on the Solar System?
Quote

That is the question.

Answer: We don't know. The position is unclear. And the rest . . . . . . ? N/A = not applicable.

Cat :)
Could be mars size to jupiter size and could be way out in the outskirts 100-1000 au or more.
Mars size objects probably exist out somewhere in the burbs but very big jupiter size objects probably not.

A couple mars size objects at a few 100 AU would be almost no impact on the gravitational system and be near impossible to detect them.

Never say never though about how big our solar system might be and what it has.
 

alien117

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Hmm, there does look like neptunes orbit is being influence by a planet between the size of Neptune and Saturn maybe 15x the raidus of Earth?
 
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Good point, but if it was a black hole, Neptune would be gone already.
This isn't really true but Helio covered that already

:) Nice pun, but not because a BH would hurt Neptune, but because a planetary mass BH evaporates too quickly. [IIRC]

The planets only orbit due to gravity and they don't care if the primary mass is fluffy or close to a singularity. Newton formalized the principle where the c.g. is at the center, after all.
Technically a planet massed black hole if formed in the early universe could very well still be around as their hawking temperature would still be colder than the CMB Its black holes that are smaller i.e. on the order of ~10^21 kg that have been ruled out . Planet mass black holes are actually one of the few windows where hypothetical primordial black holes could constitute a small but significant fraction of "dark matter".

Realistically though we have no reason to believe Primordial Black Holes (PBH) are necessarily real or that they can form substellar masses. PBH's are a prediction of certain models of the inflation hypothesis which is only a hypothesis to try and explain why he CMB is so relatively smooth. Its only the standard best guess for how you can explain this observation but it isn't the only one one alternate idea proposal for example suggests you could get a similar result through a phase transition that decreases the number of spatial dimensions.
Alternatively if PBH's existed they may have nucleated as the cores of galaxies in the Early Universe rapidly growing into the extremely massive monstrous black holes lurking at the heart of most galaxies.


On topic I don't believe there is anywhere near enough evidence to support the existence of a Planet 9 there also isn't enough evidence to rule it out given that the only thing that has been shown is that one could explain the apparent clustering of large perihelion scattered disk objects. Thus all we can say is I we don't know. Science is an iterative process that constantly refines and updates our models of the world based on observations and thus is only ever a best approximation of "the truth" at best. Hence Truth is something like infinity an abstract notion arrival only in the sense of mathematical limits.
 
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Catastrophe

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Dragrath,
" Science is an iterative process that constantly refines and updates our models of the world based on observations and thus is only ever a best approximation of "the truth" at best."

Yes, but that does not mean that there are goblins at the bottom of the garden are presumed to exist until proved otherwise.

Cat :)
 
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Dragrath,
" Science is an iterative process that constantly refines and updates our models of the world based on observations and thus is only ever a best approximation of "the truth" at best."
Yes, but that does not mean that there are goblins at the bottom of the garden are presumed to exist until proved otherwise.

Cat :)

Yes and did I say any different?

Just because something can't be ruled out doesn't mean it exists, it is generally best to favor the simpler scenarios unless either the risk of another outcome is sufficiently large to be concerned and only for the sake if planning contingencies so you are prepared if that becomes a possibility.

It's the same reason I am doubtful that Dark Energy is real in light of the independent reevaluation of the work showing poor data analysis that failed to account for the systematic bias introduced by the assumption of isotropy at large scales or the significant sample size cosmologists would need to show even a 3 sigma standard deviation in favor of dark energy over the null hypothesis.(even discounting the possibility of systematic bias) Which is far from the 5 sigma standard deviation needed to claim a discovery.

I personally suspect the whole planet 9 thing will fizzle out when the Vera Rubin Observatory begins its survey of the sky but this isn't a scientific argument.
 
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Just because something can't be ruled out doesn't mean it exists, it is generally best to favor the simpler scenarios unless either the risk of another outcome is sufficiently large to be concerned and only for the sake if planning contingencies so you are prepared if that becomes a possibility.
There are those, however, who disparage science by abusing the phrase, "a theory is just a theory", which I assumed was where Cat was going, and not directed to you.

It's the same reason I am doubtful that Dark Energy is real in light of the independent reevaluation of the work showing poor data analysis that failed to account for the systematic bias introduced by the assumption of isotropy at large scales or the significant sample size cosmologists would need to show even a 3 sigma standard deviation in favor of dark energy over the null hypothesis.(even discounting the possibility of systematic bias) Which is far from the 5 sigma standard deviation needed to claim a discovery.
That's certainly an important field of study given the assumption DE is the most dominant force/energy, or whatever, in the universe. It's another example where we need to be understand and appreciate how the degree of reliability is critical to when engineers are handed the equations. Some things become legitimate "laws" and others dissolve or shipped off to Sillyville. :)

I personally suspect the whole planet 9 thing will fizzle out when the Vera Rubin Observatory begins its survey of the sky but this isn't a scientific argument.
I'd bet an ice cream sundae you're right. :) The counter hypothesis by (I keep forgetting her name) that the clustering is self-supportive, with other objects too far to see at this point, may be the better model.
 
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Catastrophe

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NO. "There are those, however, who disparage science by abusing the phrase, "a theory is just a theory", which I assumed was where Cat was going, and not directed to you." I did not intend that at all. Cat :)

#36. I agreed top para. The bit about goblins was surely not anti-science. It just meant you don't assume ideas like planet 9 are true until you have some evidence to support it. I won't believe in goblins on anyone's say so - I will wait for some objective observations. That is not anti0science????????? Cat :)
 
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NO. "There are those, however, who disparage science by abusing the phrase, "a theory is just a theory", which I assumed was where Cat was going, and not directed to you." I did not intend that at all. Cat :)
So what is the goblin picture I should have seen? [I tend to rush too often through posts and miss some key points.]
 

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