"Large Planet Outside Pluto's Orbit"

[Aanker]

So I've seen this mentioned a few times now in the Pluto planet status discussion and it made me remember an article I read on a popular science site a year or so ago about the idea that there may be a large planet (maybe even larger than Earth?) frozen up beyond Pluto's orbit.

I'm formulating this thread as a question because

A) I'm curious to know how many have heard of this idea, and if they've come across it on other 'look at me and my revolutionary article' pop sci sites

I want to know what the actual evidence is

C) I'm also interested in what the implications would be - are we talking about an icy wasteland formed in the primordial aeons of the solar system or a captured body?

Basically, explain/discuss pls

Disclaimer: this is not about 'niburu' or 'planet x' or whatever other alien tinfoil conspiracy theories are out there.

[Accelerando]

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The idea of a "tenth planet" has been bandied around for a long time. Originally there was speculated to be a Neptune-mass-ish object out there; there have been other speculations over the decades. It's not an uncommon idea, although I know of no evidence personally

[Tex_NL]

I too have heard about this a long time ago but never gave it much merit. But of course it's not impossible some Oort cloud debris clumped together to form a planet sized object.

[Ralathon]

This idea is centuries old. Anyway, there is only very tenuous proof for it.

The main evidence is in the orbits of long period comets. You'd expect these to come randomly from any direction. But in reality they seem to have a preference for some inclinations over others. This could be explained with a very distant planet giving them gravity slingshots. The numbers for long period comets also don't match up. If you simulate the formation of the solar system you can see roughly how much stuff there should be in the Oort cloud. But if you compare that to how many long period comets we see, there is a 2 orders of magnitude discrepancy. This would again be explained by a distant planet. The orbit of Sedna is another weird thing. Sedna has an elliptical orbit with a periapsis way past Neptune and an apoapsis about 1000 AU. Since its orbit never even comes close to Neptune it is a mystery how it ever ended up in such an elliptical orbit. And Sedna isn't alone, there are other bodies with these weird orbital parameters. All of which could be explained by another heavy object in a very distant orbit.

But, all these things could also be explained by a close pass of a few stars a couple million years back. We know that there isn't anything really big out there thanks to IR observations. But something the size of the earth could exist.

The implications depend entirely on the body that we detect. Extremely elliptical orbits with a very high apoapsis imply a interstellar capture, circular in a cleared orbit implies formation within the solar system. We can't really say until we see it. We know its possible from exoplanet observations, so it wouldn't be that big a surprise.

[benzman]

I had never heard of Nibiru so I Googled it. Found the Wikipedia article but stopped reading at about the third line. Boy, are there some total whackos out there!

[lajoswinkler]

I had never heard of Nibiru so I Googled it. Found the Wikipedia article but stopped reading at about the third line. Boy, are there some total whackos out there!

You are lucky. You've managed to avoid one of the worst poops in the meadows of the World Wide Web.

[smjjames]

Well, there was some discussion/mention about Sedna and its extreme orbit which could be caused by an unseen planet, perturbed by a passing star (could be as far back while the sun was still in its loose birth cluster), or even captured from a passing star.

There is good simulation evidence that there was a third ice giant which got thrown out, maybe it had a close encounter with that as it left the system.

[Scotius]

And that's the thing. We can find all kinds of dwarf planets, asteroids etc. beyond Pluto's orbit. But we can't find a massive body rivaling Eart, or even Neptune in size? Nah.

[CptRichardson]

And that's the thing. We can find all kinds of dwarf planets, asteroids etc. beyond Pluto's orbit. But we can't find a massive body rivaling Eart, or even Neptune in size? Nah.

Space is big. Like, unbelievably, impossibly big. You'd think big is walking down the country lane to the nearest store, but space is way bigger than that.

Now go and try to find an Earth-sized planet at 80 AU. Or maybe 1000 AU. This is trying to find a single grain of rice in a mile-high haystack hard.

[vger]

And that's the thing. We can find all kinds of dwarf planets, asteroids etc. beyond Pluto's orbit. But we can't find a massive body rivaling Earth, or even Neptune in size? Nah.

Pluto was only found by accident, while searching for said planet.

Anyway... from Wikipedia. Looked this up because all this Pluto excitement had me wondering, "What ever happened to that 'other' unaccounted-for planet?"

Harrington died in January 1993, without having found Planet X. Six months before, E. Myles Standish had used data from Voyager 2's 1989 flyby of Neptune, which had revised the planet's total mass downward by 0.5%â€â€an amount comparable to the mass of Marsâ€â€to recalculate its gravitational effect on Uranus. When Neptune's newly determined mass was used in the Jet Propulsion Laboratory Developmental Ephemeris (JPL DE), the supposed discrepancies in the Uranian orbit, and with them the need for a Planet X, vanished. There are no discrepancies in the trajectories of any space probes such as Pioneer 10, Pioneer 11, Voyager 1, and Voyager 2 that can be attributed to the gravitational pull of a large undiscovered object in the outer Solar System. Today, most astronomers agree that Planet X, as Lowell defined it, does not exist.

[jwenting]

No, Nibiru does not exist.

It's an invention by ancient aliens advocates, doomsday predictions, etc.

It would have a far larger impact on the bodies of the known solar system than is observed from "unknown" sources (which would be Kuiper Belt objects, comets, and the occasional rogue planet passing closish to the solar system in interstellar space).

[Seyvern]

You are lucky. You've managed to avoid one of the worst poops in the meadows of the World Wide Web.

First I heard of this conspiracy theory as well. Had to read about it. Very sad cult behavior. The woman driving this cult apparently convinced a lot of people to kill all their pets in 2003 because of the impeding apocalypse. I suppose thats better than the Heaven's gate cult, but certainly cut from the same cloth.

[kiwi1960]

Pluto was only found by accident, while searching for said planet.

Anyway... from Wikipedia. Looked this up because all this Pluto excitement had me wondering, "What ever happened to that 'other' unaccounted-for planet?"

Yes, I have always known it as Planet X ... given even with telescopes, Pluto is only the size of back ground stars (or smaller) means that there could be an entire plethora of planets and we would not know... and if we did suspect there was a planet, we would need to be looking at the exact right place to find it.... and they only way to find it, id to take a photo, then wait for some time, take another photo and see if any of the objects has moved.

Its not like looking for a needle in a haystack, its like looking for that one grain of sand on the beach....

having said that, while other planets may well be discovered in the future, I doubt they will find Planet X along the lines of the size they think it is....

Pluto was found in 1930... it took us since the telescope was invented to find it... given that record.... anything can appear and soon too.

[Shpaget]

Pluto was only found by accident, while searching for said planet.

Is it an accident if you look for a planet and find a (dwarf) planet?

In any case, since then we have armed ourselves with some very neat space telescopes that combed the skies and came up with nothing matching the description of Nibiru (Earth sized planet, or even a brown dwarf) which would glow in IR like there's no tomorrow.

[Darnok]

No, Nibiru does not exist.

It's an invention by ancient aliens advocates, doomsday predictions, etc.

It would have a far larger impact on the bodies of the known solar system than is observed from "unknown" sources (which would be Kuiper Belt objects, comets, and the occasional rogue planet passing closish to the solar system in interstellar space).

Ancient aliens advocates use SETI to find signals send by aliens millions of years ago

Or they are searching for patterns in our DNA or in cosmic microwave background (CMB) and they call it science.

Even if SETI would find any signal it would be useless, because we would never be able to answer it (someone didn't think for second before SETI started, why would any civilization send any signal in very possible hostile space?)

Pattern in DNA could be useful and would mean that GMO and any other genetic experiments are totally wrong.

Pattern in CMB also is useless, because it wouldn't help us to contact anyone.

After thinking that way you see that ancient aliens in our solar system or as builders of pyramids are not only easier to study, but also any found evidence would be far more useful than SETI.

Like Eris there could be many planets in many different orbits and with little luck they can be synchronized in way they are balancing their gravitational influence (look at the Moon how much luck it needed to orbit Earth in way we can only see same side?).

[Fel]

Even if SETI would find any signal it would be useless, because we would never be able to answer it (someone didn't think for second before SETI started, why would any civilization send any signal in very possible hostile space?)

They're looking for signs of artificial electromagnetic radiation, which is much different from "a signal." Whether we intend to or not, we are leaking EM Radiation like crazy into space. Of course, the signal strength decays rapidly the further out you go and becomes comparatively small over background noise, and the chances of finding such radiation go down very rapidly...

But don't mock something you simply don't understand. A pluto flyby is useless because it "doesn't directly help us," or going to the moon is useless because "the money is better spent here on earth."

IF they discover life, veritable proof of live beyond our world, it will be big news, regardless of whether we can contact them or not.

[Darnok]

They're looking for signs of artificial electromagnetic radiation, which is much different from "a signal." Whether we intend to or not, we are leaking EM Radiation like crazy into space. Of course, the signal strength decays rapidly the further out you go and becomes comparatively small over background noise, and the chances of finding such radiation go down very rapidly...

But don't mock something you simply don't understand. A pluto flyby is useless because it "doesn't directly help us," or going to the moon is useless because "the money is better spent here on earth."

IF they discover life, veritable proof of live beyond our world, it will be big news, regardless of whether we can contact them or not.

Then what good can come with SETI? We find some random signal from ancient civilization that is dead for millions of years and what we will do with it?

Meanwhile any studies closer to Earth or on Earth are called as "crazy", just because aliens on distant planets are ok, but aliens that could exists or visit Earth, before we humans learned how to build wigwam, how to farm or write on clay stones, are crazy ideas.

As for Pluto flyby where did I said it is useless?

IMO we should put few satellites in orbits of every planet in our solar system and drop few more rovers that we have currently on Mars to study every planet in our solar system much better. We should, instead of stupid Voyager missions, send many probes with telescope so we could use it today to track objects passing through the solar disc, because that is easiest way, we know, to explore and study space objects.

[YNM]

As for Pluto flyby where did I said it is useless?

IMO we should put few satellites in orbits of every planet in our solar system and drop few more rovers that we have currently on Mars to study every planet in our solar system much better. We should, instead of stupid Voyager missions, send many probes with telescope so we could use it today to track objects passing through the solar disc, because that is easiest way, we know, to explore and study space objects.

New Horizons is flyby mission too, the same as Voyagers back then. The irony is huge, I know.

IMO we should just concentrate on JWST. With all its huge space mirrors, IR sensors and IR spectrograph, it should answer our need to search for very far, very small (compared to it's distance, mind you, not to other space objects) objects teetering at the edge of the Solar System, not to mention it can also be used for other things (like, nebulae and distant galaxies). Then we should get a lot of people (or lots of computers ?) to track for any moving dots, and telling us about it. Then, all orbits plotted, let's hope for another flyby mission !

[Accelerando]

Then what good can come with SETI? We find some random signal from ancient civilization that is dead for millions of years and what we will do with it?

Meanwhile any studies closer to Earth or on Earth are called as "crazy", just because aliens on distant planets are ok, but aliens that could exists or visit Earth, before we humans learned how to build wigwam, how to farm or write on clay stones, are crazy ideas.

The Milky Way is 100,000 light-years across. Any signal from within our galaxy is going to reach us within that timeframe - not exactly "the-lifespan-of-human-industrial-civilization" timescales, but certainly within the bounds of human existence.

At any rate, contacting these civilizations isn't necessarily the point, although it makes for good press. Importantly, locating other civilizations, especially those with the power to be noticed across hundreds or thousands of light-years, helps us establish a framework for where we're going to be headed, if we intend to become a spacefaring society (or at least long-lasting enough to be spacefaring). If we could learn something about the characteristics of sapient alien societies - what kinds of energies they're capable of employing, how much material they're capable of extracting from their systems and lobbing around are things I assume may be among the first things we learn, and then how all that stuff is distributed - it could contribute to a roadmap for our own development, and give some indication of what challenges and dangers we'll face in the future.

CMB detections are far from useless. They help confirm or disprove, to my knowledge, fundamental theories of physics, which makes them particularly useful to extremely prevalent Earth tech that depends on such things like electronics (quantum physics, etc) and GPS (relativity)

Similarly, if we could somehow find evidence of, say, extraterrestrials using a warp drive, that could similarly help develop our practical knowledge. That's probably a far-out example, so if anyone can correct me or suggest a more grounded one that'd be nice.

We don't necessarily need to receive messages from the stars to see extraterrestrials, either (although it also makes good press). "Zen SETI", for instance, proposes looking for evidence of ETI activity by analyzing non-waterhole astronomical data for evidence of large-scale ETI involvement, a la searching for infrared emissions from Dyson spheres, or large solar power constellations in general, perhaps. Looking at concentrations of metal in other solar systems to determine whether an industrial civilization has lots of infrastructure out there is another idea. If we could get telescopes out to the sun's gravitational lens, it may even be possible to directly see other worlds with significant clarity. And if we do find something within a 200 light-year bubble, communicating with it (if desired) could be done within the time industrial society has lasted so far.

They might not send signals out of fear, as you note, or perhaps simply because they don't want to spend the resources, but if the galaxy is indeed a quiet place, it'd definitely be worth looking out to see who we'll be dealing with should we ever leave the solar system.

---

I don't personally think it's useless to search for life within our solar system. Enceladus and Titan stand out as good targets to me. And perhaps there is some planet out there in the far reaches of the solar system, but to my knowledge, people have been searching for a while and they have yet to find significant evidence of one, so people discredit others who insist that there must be a very specific planet there that is just being covered up/scientists are ignorant/etc. And there's a lot more stars and galaxies out there than there is currently estimated mass to form planets in the Oort Cloud, between 4 and 80 Earth masses. Doesn't mean that nobody is looking out for objects in the Kuiper Belt/Oort Cloud.

Either way, there's no need to discredit either line of exploration, interstellar or in-solar-system.

Edited July 15, 2015 by Accelerando

[KerikBalm]

This idea is centuries old. Anyway, there is only very tenuous proof for it.

The main evidence is in the orbits of long period comets. You'd expect these to come randomly from any direction. But in reality they seem to have a preference for some inclinations over others. This could be explained with a very distant planet giving them gravity slingshots. The numbers for long period comets also don't match up. If you simulate the formation of the solar system you can see roughly how much stuff there should be in the Oort cloud. But if you compare that to how many long period comets we see, there is a 2 orders of magnitude discrepancy. This would again be explained by a distant planet. The orbit of Sedna is another weird thing. Sedna has an elliptical orbit with a periapsis way past Neptune and an apoapsis about 1000 AU. Since its orbit never even comes close to Neptune it is a mystery how it ever ended up in such an elliptical orbit. And Sedna isn't alone, there are other bodies with these weird orbital parameters. All of which could be explained by another heavy object in a very distant orbit.

But, all these things could also be explained by a close pass of a few stars a couple million years back. We know that there isn't anything really big out there thanks to IR observations. But something the size of the earth could exist.

The implications depend entirely on the body that we detect. Extremely elliptical orbits with a very high apoapsis imply a interstellar capture, circular in a cleared orbit implies formation within the solar system. We can't really say until we see it. We know its possible from exoplanet observations, so it wouldn't be that big a surprise.

Best answer so far, but I think wikipedia also does a pretty good job here:

https://en.wikipedia.org/wiki/90377_Sedna#Origin

They observed that, unlike scattered disc objects such as Eris, Sedna's perihelion (76 AU) is too distant for it to have been scattered by the gravitational influence of Neptune.

...

If Sedna formed in its current location, the Sun's original protoplanetary disc must have extended as far as 75 AU into space.[34] Also, Sedna's initial orbit must have been approximately circular, otherwise its formation by the accretion of smaller bodies into a whole would not have been possible, because the large relative velocities between planetesimals would have been too disruptive. Therefore, it must have been tugged into its current eccentric orbit by a gravitational interaction with another body.[35] In their initial paper, Brown, Rabinowitz and colleagues suggested three possible candidates for the perturbing body: an unseen planet beyond the Kuiper belt, a single passing star, or one of the young stars embedded with the Sun in the stellar cluster in which it formed.

...

The trans-Neptunian planet hypothesis has been advanced in several forms by a number of astronomers, including Rodney Gomes and Patryk Lykawka. One scenario involves perturbations of Sedna's orbit by a hypothetical planetary-sized body in the inner Oort cloud. Recent simulations show that Sedna's orbital traits could be explained by perturbations by a Neptune-mass object at 2,000 AU (or less), a Jupiter-mass (MJ) at 5,000 AU, or even an Earth-mass object at 1,000 AU.[37][41] Computer simulations by Patryk Lykawka have suggested that Sedna's orbit may have been caused by a body roughly the size of Earth, ejected outward by Neptune early in the Solar System's formation and currently in an elongated orbit between 80 and 170 AU from the Sun.[42] Mike Brown's various sky surveys have not detected any Earth-sized objects out to a distance of about 100 AU. However, it is possible that such an object may have been scattered out of the Solar System after the formation of the inner Oort cloud.

...

Each of the proposed mechanisms for Sedna's extreme orbit would leave a distinct mark on the structure and dynamics of any wider population. If a trans-Neptunian planet was responsible, all such objects would share roughly the same perihelion (≈80 AU). If Sedna were captured from another planetary system that rotated in the same direction as the Solar System, then all of its population would have orbits on relatively low inclinations and have semi-major axes ranging from 100–500 AU. If it rotated in the opposite direction, then two populations would form, one with low and one with high inclinations. The perturbations from passing stars would produce a wide variety of perihelia and inclinations, each dependent on the number and angle of such encounters.[43]

Acquiring a larger sample of such objects would help in determining which scenario is most likely.

...

In 2014, astronomers announced the discovery of 2012 VP113,[19] an object half the size of Sedna in a 4200-year orbit similar to Sedna's and a perihelion within Sedna's range of roughly 80 AU,[49] which led some to speculate that it offered evidence of a trans-Neptunian planet.

[peadar1987]

Pattern in DNA could be useful and would mean that GMO and any other genetic experiments are totally wrong.

Of course DNA has patterns, it's an information-coding system. I don't see how this makes GMOs wrong.

Pattern in CMB also is useless, because it wouldn't help us to contact anyone.

Patterns in the CMB reveal the very earliest moments of the universe, and can help to shed some light on how it began. That is one of the most fundamental questions we as a species can ask, and is far from useless.

After thinking that way you see that ancient aliens in our solar system or as builders of pyramids are not only easier to study, but also any found evidence would be far more useful than SETI.

It would be a waste of time. We know that humans built the pyramids, we know that humans evolved through natural selection from an ape-like ancestor, and that Methone isn't actually an alien spaceship. We might as well study whether my forks and spoons are from Proxima Centauri.

Like Eris there could be many planets in many different orbits and with little luck they can be synchronized in way they are balancing their gravitational influence (look at the Moon how much luck it needed to orbit Earth in way we can only see same side?).

No, no they can't. Even if planets were arranged in such a way that their net gravitational influence on, say, Jupiter, was zero (which is incredibly unlikely in itself), their influence on every single other body in the solar system would be non-zero.

And the moon is tidally locked to earth, it's not just some lucky coincidence: https://en.wikipedia.org/wiki/Tidal_locking

The majority of moons are tidally locked to their parent bodies.

[cantab]

A planet-sized object beyond Neptune remains a possibility, but with sky surveys being done all the time the net is closing in. As discussed the orbits of the bodies we know give us reason to look for something, at least.

[Drunken Hobo]

Space is big. Like, unbelievably, impossibly big. You'd think big is walking down the country lane to the nearest store, but space is way bigger than that.

You got the quote wrong!

[JetJaguar]

A planet-sized object beyond Neptune remains a possibility, but with sky surveys being done all the time the net is closing in. As discussed the orbits of the bodies we know give us reason to look for something, at least.

FWIW, the WISE satellite did a survey of the entire sky in infrared, and it would have detected anything Neptune-sized out to 700 AU, and anything Jupiter-sized to 1 light-year, so that establishes an upper bound on anything that could be orbiting out there.

[Rakaydos]

I recall reading an article about how the main gas giants of our silar system could not have formed in their current orbits, but that if we assume another planwt formed between them, our current planets would move to their current orbits while ejecting the extra, possibly from the system entirely.