Surely it is no longer an extrasolar planet once it is part of our Solar System, regardless of how it formed or ended up here? I was under the impression that extrasolar simply implies that it does not orbit the Sun.

Perhaps it is about Nibiru , Nemesis or Planet X so called and was ruled by jupiter and said on Realitatea TV that is 5 times greater as Planet Earth and has less not know how many degrees and that is heading towards speed and our planet will destroy in five days . This planet Nibiru is like a ghost through space so I read on google .

Was it confirmed to be another planet?

If planets can be exchanged, it seems likely that close passes by other stars known to happen frequently over geologic timescales would have strongly affected the outermost parts of our solar system, especially the Oort Cloud. Most likely, some portions of the original Oort Cloud were lost to other stars and some portions were gained from other stars. So the nearest samples from other solar systems are probably conveniently in orbit around the sun.

Every time we explore further out into the solar system we are supervised by the complexity encountered. This line of reasoning suggests that will continue.

If planets can be exchanged, it seems likely that close passes by other stars known to happen frequently over geologic timescales would have strongly affected the outermost parts of our solar system, especially the Oort Cloud. Most likely, some portions of the original Oort Cloud were lost to other stars and some portions were gained from other stars. So the nearest samples from other solar systems are probably conveniently in orbit around the sun.

Every time we explore further out into the solar system we are [ supervised by ] the complexity encountered. This line of reasoning suggests that will continue.

I think you might have meant "surprised", but I got where you were going...:-)

the problem with talking up the details of a predicted discovery based on mathematical simulation is that WE HAVE NOT DISCOVERED IT YET AND SO YOU WILL LOOK REALLY STUPID IF IT ISN'T DISCOVERED SOON.

oh , it's an exoplanet...balbalblala. FIND IT FIRST, CONFIRM THE PREDICTION, THEN GO ON TO ELABORATE.

WHY?
THIS ISN'T SCIENCE , IT IS SPECULATION ABOUT A PREDICTED OBJECT. sounds a lot like the pattern of funding global catastrophe prediction outcome research.....to me.

Good theory. I had thought it a companion star. A long time.
Find it and see. Fascinating. We have a general idea of the inclination of the orbit to the ecliptic.
It is a lot of space to search for a dim, perhaps dark, object.
The math hasn't lied to us. Something is out there.

@ TB

THIS ISN'T SCIENCE , IT IS SPECULATION . . .

Fortunately, scientific discovery doesn't depend on your opinion.

. . . and our planet will destroy in five days .

I can't even imagine what living with this kind of paranoia must be like.

. . . and our planet will destroy in five days .

I can't even imagine what living with this kind of paranoia must be like.

Melancholia was a great film for nihilism genre

"show that it is highly likely that the so-called Planet 9 is an exoplanet".

You mean former exoplanet, and they don't as the (paywalled) paper abstract claims "these [necessary ] criteria may be simultaneously satisfied. In a few per cent of slow close encounters in a cluster".

That is a too small rate to be even regarded as a likely pathway, as there are other proposals. (Say, the discoverers lists a few.) One of those should be a high likelihood pathway, or if not the odds are against this one.

@Mark: Correct, I have seen claims on models showing some 10 % (IIRC) of Oort clouds bodies being of foreign descent.

But the effort to get to the Oort cloud on a logarithmic scale (which maps to the exponential increase of technology and economy) was charted by xqcd comic once to be the largest step ever. Stars will be easy after that (especially since they will come closer now and then). So "convenient" isn't what I would call it.

That reality doesn't matter to crackpots is shown here, as if Planet Nine exists it is manifestly neither Nibiru (too far out), Nemesis (too far in) or Planet X (too small effect on the inner system).

In fact it makes the space for the tow fantasy planets much smaller, since it inhabits a large part of the solar system that they could have visited but wouldn't be able to if PN exists.

But having rejection and problems thrown in their face excites them. Thus is the life for a crackpot.

(1) We don't know if this planet even exists yet.
(2) If it does exist, it wouldn't be Planet 9, as there are 13 objects known to be geophysical planets orbiting the Sun: Mercury, Venus, Earth, Mars, Ceres, Jupiter, Saturn, Uranus, Neptune, Pluto, Makemake, Haumea, and Eris. Assuming this as yet undiscovered object turns out to be there, it would be the 14th known planet of the Sun. Planet X would be a more appropriate term.

Oh gawd, here come the beta-reticulan believers. How much you all want to be that the Leiderites are pounding on their drums now?

(1) We don't know if this planet even exists yet.
(2) If it does exist, it wouldn't be Planet 9, as there are 13 objects known to be geophysical planets orbiting the Sun: Mercury, Venus, Earth, Mars, Ceres, Jupiter, Saturn, Uranus, Neptune, Pluto, Makemake, Haumea, and Eris. Assuming this as yet undiscovered object turns out to be there, it would be the 14th known planet of the Sun. Planet X would be a more appropriate term.

Um, no, Pluto, Makemake, Haumea, and Eris are all plutoids, or dwarf planets, not planets.

So when's the probe going out, if there's a planet, i wants to see it ! !

WG: "I think you might have meant "surprised", but I got where you were going"

Yes, you are certainly correct. I hate when that happens! :-)

OK.. So our Sun stole a planet from another star approximately 4.5 billion years ago. I feel pretty safe to say they won't want it back.

Hmmm..so if we 'stole' a planet during this encounter then our solar system may also have passed through the other's Oort cloud. That might have been a dangerous time.

(This assumes a spherical Oort cloud. AFAIK it's not yet setteld whether the Oort cloud is spherical, disc shaped, partly the one and the other...or whether it even exists at all. )

I belive the correct term is "transsolar". As in, "Agrippa is a transsolar planet because it was associated with another star, but now it orbits the Sun." Now, besides confirmation of its existence and birth system, people will argue about which restroom it uses.

the problem with talking up the details of a predicted discovery based on mathematical simulation is that WE HAVE NOT DISCOVERED IT YET AND SO YOU WILL LOOK REALLY STUPID IF IT ISN'T DISCOVERED SOON.

oh , it's an exoplanet...balbalblala. FIND IT FIRST, CONFIRM THE PREDICTION, THEN GO ON TO ELABORATE.

WHY?
THIS ISN'T SCIENCE , IT IS SPECULATION ABOUT A PREDICTED OBJECT. sounds a lot like the pattern of funding global catastrophe prediction outcome research.....to me.

Neptune was predicted before it was discovered. I don't see what you are getting so upset over.

global catastrophe prediction outcome research

What does that even mean? Did you get hit in the head with a bible?

AAP

Hmmm..so if we 'stole' a planet during this encounter then our solar system may also have passed through the other's Oort cloud. That might have been a dangerous time.

Maybe that's what caused the Late Heavy Bombardment?

Was it confirmed to be another planet?

Not yet; but they've got time on the Subaru and they're going hunting. They predict a 5-year search.

the problem with talking up the details of a predicted discovery based on mathematical simulation is that WE HAVE NOT DISCOVERED IT YET AND SO YOU WILL LOOK REALLY STUPID IF IT ISN'T DISCOVERED SOON.

I would have thought it was a hypothesis, but never mind.......

I remember reading about this in the 1970s, The book suggested that an exoplanet was responsible for the periodical slowing of Neptune's orbit when it exerts a gravitational pull as it comes near to Neptune.

Pluto is far too small to do that, so it was hypothesised that it had to be a massive planet that had so far eluded astronomers.

@BSD, Planet 9 (assuming it exists) has an orbital period of 10,000 to 20,000 years. Considering that Neptune wasn't discovered until 1846, and only completed one orbit since then (in 2011), what exact periodic slowing of Neptune's orbit were you referring to? I'd be interested to know the name of this book.

The data indicates that something is wrong unless there's an object out there at about 5 Earth masses in size. Great. Of course, there have been other calculations to explain the discrepancies, but this is the leading theory now, especially with some of the new data they've gotten recently.

Have we discovered it? No, not really, but we're pretty bloody sure that something is out there causing those gravitational anomalies. So until it's actually located, you can't run around making all kinds of wild declarations about it.
On the other hand, we know there's something, so don't start blowing all this off just because we haven't spotted it exactly.

It's kind of like your doorbell going off. You know somebody is there, even if you haven't seen them yet.

Maybe that's what caused the Late Heavy Bombardment?

That's a really hard one to answer. It would present a 'sensible' mechanism, but verifying it is going to be a doozy..

Unless (and this is always assuming that Oort clouds actually exist) : When we start measuring composition of Oort cloud objects we find two distinct populations* (or a bulge/gap along a certain sector of the cloud..as the exchange/capture/loss of such objects would be a lopsided process)

* though given that two stars passing each other by are likely to have originated in the same region of space (i.e. from the same dust cloud) the composition of their Oort cloud objects may not be radically different at all.

Since there were comments discussing science on a hypothesis that has been tested on constraints that may have some other explanation (but the most near lying ones have been rejected):

There has in fact been a prediction test as well as the post-diction ones.

Brown tweeted about a new find of yet another object in the signature orbits some time ago. (I can't remember which of the two groups it belonged to.) However I haven't seen a new paper.

@EF: "Maybe that's what caused the Late Heavy Bombardment?"

The putative LHB has had impactor flows that match the Nice models giant planet migration disturbing a still debris filled system, and that migration has been used to explain the Oort cloud too.

I think, but doesn't know, that the first explanation suggests high flow rates during a limited time whose rates and limited time would be far from what you can get from a dispersed Oort cloud disturbance.

The early time of the putative theft would have happened while the systems was still very close, else PN wouldn't have been in a wide orbit. Let us say 10 000 au as the most distant orbits we see today. The Oort cloud resides at 100 000 au or more. Sounds like it would have been a later scattered feature, as the Nice model assumes.

(1) We don't know if this planet even exists yet.
(2) If it does exist, it wouldn't be Planet 9, as there are 13 objects known to be geophysical planets orbiting the Sun: Mercury, Venus, Earth, Mars, Ceres, Jupiter, Saturn, Uranus, Neptune, Pluto, Makemake, Haumea, and Eris. Assuming this as yet undiscovered object turns out to be there, it would be the 14th known planet of the Sun. Planet X would be a more appropriate term.

Um, no, Pluto, Makemake, Haumea, and Eris are all plutoids, or dwarf planets, not planets.

Um, yes, they are planets, at least to those who adhere to the geophysical definition of planet.

@TBGL: "But the effort to get to the Oort cloud on a logarithmic scale (which maps to the exponential increase of technology and economy) was charted by xqcd comic once to be the largest step ever. Stars will be easy after that (especially since they will come closer now and then). So "convenient" isn't what I would call it."

Your logarithmic scale has hidden assumptions about the availability of increasingly effective propulsion at every level. Let's just say I hope you are right, but reaching the stars may turn out to be harder than reaching the Oort Cloud.

The term "convenient" is subjective and somewhat tongue-in-cheek here, but I argue it has merit. Can you make the best argument in favor of the extrasolar samples likely to be in orbit around the sun, being "convenient?" Hint: Just how far away could the source of some of those samples currently be?

@BSD what exact periodic slowing of Neptune's orbit were you referring to? I'd be interested to know the name of this book.

Unfortunately, I can't remember the name of the book, it was similar to "The Golden Book Of Astronomy". I was only about 11yo when I got it (c.1974). The book was a kid's book, but it was based on science and fact.

It's main focus was on the Solar System and went through facts on all of the 9 planets (when we had nine) and then moved on to other stars and other celestial bodies.

The part from which I remember reading the information in question, was about Pluto. It stated to the effect, that sometimes, Neptune's angular velocity would change, that it would slow down and speed back up again an this was observed by astronomers. They postulated it could be because; A . Pluto's elliptical orbit that brings it inside Neptune's or; B . That a more massive, as yet undiscovered and unseen planet was influencing Neptune, the 10th planet at the time.

@Mark: Tongue in cheek, that fits.