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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Catastrophe

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Helio, as you may know, I am a Korzybski fan. Names are not realities - they are vibrations in the air or marks on paper. They are useful if we remember that.

What is the point of making a rule, if the first thing you do is break it. Pluto was named a planet in error, because it happened to be the first rock they found beyond Neptune. I sometimes wonder what they would have called it, had it been inside Neptune's orbit at the time?

I have no objection to binary planets or binary dwarf planets if those best describe them at the time - and, on the proviso that the classification can be changed to better suit the current description of 'reality'. Are there, as a matter of interest, any binary planets where one is 'infinitely'' ( :) ) massive but very small, such that the cog or barycentre (is it?) is between them but closer to the smaller body?

Cat :)
 

Catastrophe

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Helio, you know that I am not being (negatively) 'funny), but I did ask you at the time how you got a body of zero mass at 1 AU clearing its orbit - or am I reading it incorrectly?

Cat :) :) :)
 
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Helio, as you may know, I am a Korzybski fan. Names are not realities - they are vibrations in the air or marks on paper. They are useful if we remember that.
Well, songs do pretty well. ;)

What is the point of making a rule, if the first thing you do is break it.
Agreed, the rule is to wait a while before breaking them. :)

Pluto was named a planet in error, because it happened to be the first rock they found beyond Neptune. I sometimes wonder what they would have called it, had it been inside Neptune's orbit at the time?
Well, Percival Lowell was the closest person this side of the pond in comparing to your Herschel. So part of the naming is due to honoring his name.

But there was no error at the time in calling Pluto a planet. Had it been the last object before tiny objects in the Kuiper Belt and Oort Cloud, it would still be called a planet, I suspect.

Are there, as a matter of interest, any binary planets where one is 'infinitely'' ( :) ) massive but very small, such that the cog or barycentre (is it?) is between them but closer to the smaller body?
No. Think of a see-saw. No matter how thin the heavier person is on one side, the fulcrum will always be closer to that person.

Remember all those FBDs? :) Those simple ones were almost all 1D force points on a beam, for example, (assuming they were perpendicular), and the moment arm to the greater force is always shorter when in balance.
 
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Catastrophe

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Helio:

"But there was no error at the time in calling Pluto a planet. Had it been the last object before tiny objects in the Kuiper Belt and Oort Cloud, it would still be called a planet, I suspect."

My point exactly. Until the current situation changed viz more 'tiny' 'planets'.

"No. Think of a see-saw. No matter how thin the h . . . "

My point was, do you still call them binary planets. You can call them binary see-saw participants if you like. I don't see the relevance. You can see where the nomenclature trips over itself. You can have a binary dwarf planet system with 5 (or 4) moons. Why should moons not be cleared? or even binary (dwarf) planets. What does need to be cleared. Obviously not satellites or trojans (small t).

All I am suggesting is, that you can name things what you like on the basis of convenience, but you can change categories (labels) as circumstances change,


Cat :)
 
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My point was, do you still call them binary planets. You can call them binary see-saw participants if you like. I don't see the relevance.
Well, if their barycenter is in space between them, then one should be able to call them a binary system if it somehow serves a pedagogical purpose in using that term. I think most don't bother doing so since a "dwarf binary system" starts to be a mouthful -- more "vibrations", as you may say, and normally not that substantive.

You can see where the nomenclature trips over itself. You can have a binary dwarf planet system with 5 (or 4) moons. Why should moons not be cleared? or even binary (dwarf) planets. What does need to be cleared. Obviously not satellites or trojans (small t).
I think moons do clear their orbits, if I understand your direction here. Are there any moons that have the same orbit? I know there are some moons that come close, one pair even swap orbits when the inner orbiting moon catches the outer one.

All I am suggesting is, that you can name things what you like on the basis of convenience, but you can change categories (labels) as circumstances change.
Agreed. We even give names to hypothetical planes (e.g. Vulcan) since every headline needs to add such things to gain prominence. Numbers for an object have little to no sizzle. :)

I give Brown and others credit for making the efforts to help get new and improved definition to "planets". Others, I know, don't agree but I don't dislike sentimental mindsets.
 
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Planet definition is rather silly IMO.
No planet in our solar system really clears out it's orbital path.
Earth gets bigger many tons a day still clearing it's.
Initially, the Earth’s orbit had millions of fellow orbiting bodies, primarily planetismals. The mass of Earth is such that it’s impossible for smaller bodies to not be tossed. The laws of gravity are reliable enough to establish what mass is great enough for any given orbital distance. Even Trojans are temporary.
 

Catastrophe

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BBC Focus Magazine No. 12 "The Ultimate Guide to the Solar System" 2019 Planet X

"Astronomers are increasingly convinced there is a giant ninth planet lurking out beyond Neptune."
"While a few aligned objects could be dismissed as an unlikely coincidence, now a total of ten have been discovered."
"With all of these objects sharing similar orbital properties, the chances of their alignment being a fluke drops to just 0.0001%. The leading explanation is that there is an otherwise unseen planet herding these planets with its gravity."
"For the planet to be acting in this way, it would have to be ten times more massive than the Earth, take at least 10,000 years to orbit the Sun, and sit over 200 times further out than our planet. This enormous distance makes hunting it down, and photographing it, tricky."


Cat :)
 
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Thanks Cat. I was curious how many more, since the first 6, may have been found.

It's a little odd for the last quoted statement to claim a minimum of both 10k years for the period and 200AU for the distance. A 10k year period requires a distance of over 450AU. But they did use "further", not "farther" so they are further from being accurate by not stating the farther distance. ;)
 
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When it comes to objects which aren't there, I suppose guesses can get a little fragile.
Well, the guesses suggest something might be there, else why bother?

As usual, it all boils down to the objective evidence and our ability to make use of it. The original discovery of the 6 objects gives us very unusual objective evidence. It's not just that they are in the same orbit, as is often stated, but that all, or most, the other parameters also align together as well. These are somewhat unique orbits with their inclinations and perihelion points, etc.

So it's not hard to see why they (eg Brown) have gone beyond just guessing by introducing hypotheses that are scientific, mainly because the claims made are testable.

I enjoyed Brown's self-encouragement he mentions in his book whereby his daughter told him she was bothered with him demoting Pluto, so much so, that she wants him to make up for it by discovering another planet. :)
 
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Initially, the Earth’s orbit had millions of fellow orbiting bodies, primarily planetismals. The mass of Earth is such that it’s impossible for smaller bodies to not be tossed. The laws of gravity are reliable enough to establish what mass is great enough for any given orbital distance. Even Trojans are temporary.
A better definition of planet i think is needed.
Clearing an orbital path never really happens for any planet.
We need a solid definition of what is cleared and what isn't with specific rules.
Having enough gravity to be round does.
Orbiting a star does.

When you think about it Charon isn't a moon since a moon only orbits a planet and Pluto under the clear orbit isn't one.
 

Catastrophe

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VPE, "Clearing an orbital path never really happens for any planet."

Generally, I agree with you completely. All sorts of other sub-conditions have to be attached to cover eventualities including moons, trojans etcetera. Then do you apply the same rules to dwarf planes?
If so, what happens when a planet or dwarf planet acquires satellites like Charon, Moon, across to Deimos and Phobos.
Incidentally the remnants we know as Mercury and Venus are the result of orbit clearance. Impacts caused proto-Mercury to loose a lot of its mantle, and caused proto-Venus to rotate (just) in the opposite direction.

The point I am making is that any rules should be made foolproof so that a status is not changed if, for example Mercury or Venus were to acquire Mars's sized (D and P) satellites. If you robbed Mars of planetary status because it did not get rid of D and P, then Venus would lose planetary status if it acquired a 'comet' (or post-comet remnant) or an asteroid as a satellite. So, you have to allow satellites (so the rule does not change), but what about trojans (small 't')?

Cat :)
 
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Capturing a moon is indicative of planets. The larger the planet the more capable it is for capturing them. A true “planet” will toss co-orbiting objects, but it’s implied that capture would also be possible. It’s very hard for small bodies to snag another into a permanent orbit.
 
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Catastrophe

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Helio, I just think that this 'clearing orbit' condition is non-sensical. You can't demote Jupiter because it has Trojans (capital - because they were originally so named). Thus Jupiter has trojans specifically called Trojans. No other planet can have Trojans, only trojans.

Perhaps Mars' Deimos and Phobos should be called satellites instead of moons, since they were possibly just captured bits of junk. Maybe there should be a lower limit to the term moon, perhaps sphericity. I think this is often implied anyway.

Cat :)
 
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Helio, I just think that this 'clearing orbit' condition is non-sensical.
The use of clearing an orbit does appear as an ad hoc measure just to force a limit on the no. of planets. Many agree with you, but I prefer to not see hundreds of new and unnamed planets slowly accumulate on a long list, all small objects but massive enough to be round.

You can't demote Jupiter because it has Trojans (capital - because they were originally so named). Thus Jupiter has trojans specifically called Trojans. No other planet can have Trojans, only trojans.
Ah, that makes sense. Thanks. It’s amazing that Jupiter hosts over 8,000 Trojans (L4 & L5).

Perhaps Mars' Deimos and Phobos should be called satellites instead of moons, since they were possibly just captured bits of junk. Maybe there should be a lower limit to the term moon, perhaps sphericity. I think this is often implied anyway.
Agreed. It is worth the tiny effort to present a rough size by using a simple label, or labels. ”Moonlets” (unround ;) ) might be a fair synonym for satellite, avoiding the artificial connotation, when applicable.

iPad
 

Catastrophe

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Helio, "Maybe there should be a lower limit to the term moon, perhaps sphericity."

I was referring to moons, not planets. My views about planets are as I believe to be current nomenclature. I am not a Pluto worshipper. There are 8 planets. Below that there are dwarf planets.
When it comes to moons (which I was talking about) sphericity may be a criterion? I am talking about sphericity of moons. I have no objection to moonlets and then 'junk'.

You also posted: "Many agree with you, but I prefer to not see hundreds of new and unnamed planets slowly accumulate on a long list, all small objects but massive enough to be round."
In fact you implied that I differed from your opinion, whereas I did not, since my 'sphericity' applied in context to moons. :) :) :) The second para was only about moons/satellites.


Cat :)
 
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VPE, "Clearing an orbital path never really happens for any planet."

Generally, I agree with you completely. All sorts of other sub-conditions have to be attached to cover eventualities including moons, trojans etcetera. Then do you apply the same rules to dwarf planes?
If so, what happens when a planet or dwarf planet acquires satellites like Charon, Moon, across to Deimos and Phobos.
Incidentally the remnants we know as Mercury and Venus are the result of orbit clearance. Impacts caused proto-Mercury to loose a lot of its mantle, and caused proto-Venus to rotate (just) in the opposite direction.

The point I am making is that any rules should be made foolproof so that a status is not changed if, for example Mercury or Venus were to acquire Mars's sized (D and P) satellites. If you robbed Mars of planetary status because it did not get rid of D and P, then Venus would lose planetary status if it acquired a 'comet' (or post-comet remnant) or an asteroid as a satellite. So, you have to allow satellites (so the rule does not change), but what about trojans (small 't')?

Cat :)
Totally agree. Needs a bullet proof definition.
Must be X size, must orbit it's star, must have enough gravity to form a sphere ETC.

As we look around the universe we are sure to find massive planets that don't clear an orbital path due to other worlds colliding or just much stuff in the suns orbit.
Sad to think without a bullet proof setup they will become non planets.
 
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Helio, "Maybe there should be a lower limit to the term moon, perhaps sphericity."

I was referring to moons, not planets. My views about planets are as I believe to be current nomenclature. I am not a Pluto worshipper. There are 8 planets. Below that there are dwarf planets.
When it comes to moons (which I was talking about) sphericity may be a criterion? I am talking about sphericity of moons. I have no objection to moonlets and then 'junk'.

You also posted: "Many agree with you, but I prefer to not see hundreds of new and unnamed planets slowly accumulate on a long list, all small objects but massive enough to be round."
In fact you implied that I differed from your opinion, whereas I did not, since my 'sphericity' applied in context to moons. :) :) :) The second para was only about moons/satellites.


Cat :)
Maybe a moon should also be a sphere or be called a moonlet if it's not.
 

Catastrophe

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After Mars, decreasing size of objects in the Solar System are:

Ganymede (moon of Jupiter)
Titan (moon of Saturn)
Mercury (planet)
Callisto (moon of Jupiter)
Io (moon of Jupiter)
Moon
Europa (moon of Jupiter)
Triton (moon of Neptune)
Pluto (dwarf planet)
Eris (dwarf planet)

Sometimes the last two are reversed. After that it is all moons and asteroids for quite a while: Haumea, Titania, Rhea, Oberon, Iapetus, Makemake, 2007 OR10, Charon, Umbriel, Ariel, Dione, and so on. You may find the order of these differs as, as you go down the list, the smaller the differences and the more subject to change.
Eris and above are all fairly spherical, as is Titania, but Haumea is definitely not. Rhea and Oberon are rounded, but Iapetus is rather oblate. After these, more will be less rounded.

Cat :)
 
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