About that Giant Planet Possibly Hiding in the Outer Solar System…


An old story got new legs this week as word went viral of a possible new 9th planet in our solar system – a gas giant bigger than Jupiter – which could be hiding somewhere in the Oort Cloud, just waiting to be found.

An article this week in The Independent suggested the new planet, called Tyche, had already been found among data from the WISE mission. This prompted the WISE team to post a rebuttal on their Facebook page: “Not true. A pair of scientists published a paper stating that if such a big planet exists in the far reaches of the Solar System, then WISE should have seen it. That is true. But, analysis over the next couple of years will be needed to determine if WISE has actually detected such a world or not.”

To make sense of this all, Universe Today sought out a scientist who has looked at the outer solar system as much as anyone, if not more: Mike Brown, of Eris, Haumea and Makemake fame – to get his take on Tyche.

“Yes,” said Brown, “this is all getting pretty funny these days!”

The story starts at least a decade ago. For years John Matese of the University of Louisiana at Lafayette and colleague Daniel Whitmire have been trying to figure out why many of the comets that originate from way out in the distant-most part of our solar system — the Oort Cloud — have strange orbits that don’t jive with theories of how comets should behave. The two scientists first suggested that the gravitational influence from a dark companion to the Sun — a dim brown-dwarf or red-dwarf star — was sending comets careening towards the inner solar system. They called it Nemesis, (another thing that went viral), but the Nemesis idea has widely been refuted.

Last year, Matese and Whitmire suggested that possibly a large planet four times the mass of Jupiter in the Oort Cloud could explain why long-period comets appear to be clustered in a band inclined to the ecliptic instead of coming from random directions. (Here’s their paper.)

Then came a revival of their theory with several articles about it this week, reporting it as seemingly fact.

Could there possibly be a giant planet 500 times as distant as Neptune?

“Absolutely,” Brown said. “Many people have speculated about such possibilities for a long time. It’s an intriguing idea because, well, it would be fun, to say the least.”

But beyond fun and excitement, is there actually any evidence for it?

The layout of the solar system, including the Oort Cloud, on a logarithmic scale. Credit: NASA

“Well, the quality of the data that Matese and Whitmire have to work with is pretty crummy –no fault of their own — it’s just the historical record of where comets have come from,” Brown said in an email. “I don’t believe that anyone understands the ins and outs of the data set well enough to really draw a robust conclusion. But, Matese and Whitmire did the best they could and think the data point to something out there.”

Does Brown think there is really something out there?

“Well,” he said, “if I had to bet one way or another I’d bet no. The data don’t convince me, and there is no other hint anywhere that such a thing is real. So I’m pretty skeptical.”

That being said, however, Brown believes WISE really does have a good chance of detecting this type of object way out there – if it exists — even if the predictions have nothing to do with the real object.

“This is something that people will absolutely be looking for when the data are released,” Brown said, “and, indeed, the WISE team is undoubtedly already looking for — not because of the prediction, but simply because it’s the right way to search this unknown region of the solar system!”

So don’t worry about the International Astronomical Union having to confirm or name a new planet in our solar system, at least for now.

22 Replies to “About that Giant Planet Possibly Hiding in the Outer Solar System…”

  1. It would be VERY interesting to find such an object under Sol’s influence especially if proven to have been formed near another star…. but the size of Neptune? Good luck on that!

  2. I have been eagerly awaiting the release of the WISE data for just this kind of reason. A Jupiter mass object, if it exists could release enough internal heat to have been detected by WISE. I like the Matese and Whitmire article in that they are giving a prediction of where to look for such an object. There is always a flurry of such predictions before data from an important instrument is reelased.This at least makes the search a more exciting one. I don’t think anyone truly knows the odds of there being such an object at such a distant orbit (50k AU in this instance), but I am in the camp that it is likely. The prevailing theory now is that the Oort contains too much material to be leftover remenants from gravitational interactions within this solar system, but rather it is a pool of material from Sol’s nascent stellar cluster. Such a pool of material certainly could include a wayward gas giant ejected from a nearby star. Stars found in very distant orbit around other stars are likely captured in a similar fashion, say for instance Proxima Centauri.
    One question I have that probably can’t be answered is what the threshold of detection is for such planets. The answer depends on how much internal heat a planet radiates, and that can vary widely for objects of a given mass and density. If I recall correctly a Neptune sized object should not release enough heat to be detectable by this instrument.

  3. I think Brown makes a very good argument, as most always.

    I briefly looked at the paper and my beef, apart from “crummy” statistics, is that they predict and test a model dependent statistic. And they do that at a bayesian ratio of max 10, I believe, so not really 3 sigma certainty. They admit they fail to predict the inner Oort cloud statistics, and they admit that there are what I gathered more main stream models that predict the usual statistics better.

    In my eyes the paper is thrice removed from usual prediction in the first case (predict internal phenomena, test model using bayesian likelihoods instead of test data on frequentist observations, not enough certainty to test), and fails prediction in the second. (And if the other models do as badly there, it is worse elsewhere.)

    Also, and Greg’s commentary touches on this, IIRC Tyche mass is finetuned to not been detected before yet having effect. If so, the usual runaround, huh!? But I may be misremembering.

    don’t worry about the International Astronomical Union having to confirm or name a new planet in our solar system, at least for now.

    Yes, it _would_ easily clear its orbit (lambda > 1), wouldn’t it? The Oort cloud masses ~ 5 Earths AFAIU. It must be enough to plunk such a mass in there, not enough contenders.

    1. This might be a minor point, but worth debating. I have alluded to it in previous posts. It regards the IAU definition of a dwarf planet including the criterion that a planet must clear its neighborhood/orbit. If a large planet is found orbiting within the oort cloud, there may be no way for that to happen. At such a distance the orbital period will be immense. Also there are a large number of smaller objects who’s orbits will be perturbed into this planet’s orbital zone before it completes an orbit. Worse yet, there will not be any way to prove that the orbit of such a distant planet really has been cleared. I believe that once such objects are discovered in abundance in other solar systems or if one is discovered in this one, that the IAU will have to qualify this criterion in some way. My own preference is to add an absolute mass or diameter criterion above which an object is considered a planet. A diameter of 5000 kilometers makes sense to me.

      1. An even better debate that I don’t hear much of is how to separate twin/double/binary planets from a planet and moon. Should a ratio of mass or diameter be used? The present definition in unofficial and that is that the barycenter (center of gravity) should be above the surface of both planets. I believe it is time that the IAU state this definition, rather than react hurriedly only when it becomes necessary.

  4. I’m assuming the only way for a planet to be out there is for it to be a rogue planet from another star. Am I right or wrong here?

  5. I would not hold my breath on this. However, it is not impossible. If such a planet exists it might suggest there is a distribution of bodies through interstellar space. Microlensing has found brown dwarfs in interstellar space, so there might also as well be planets.


  6. It’d be really cool to find another gas giant modulating the Oort cloud, but desire alone without evidence has no bearing on if this planet actually exists.

  7. I suppose any rogue planets out there would have been either ejected from solar systems, or formed on their own in molecular clouds just like stars do but on a smaller scale.

    If there is a planet in the outer reaches of the Solar System, then I’m guessing it must be either a captured rogue or formed in the inner Solar System and migrated way out there. The second one is not such an unbelievable concept. Our current belief regarding the Oort cloud is that most of those comets formed closer in and were flung further out by the planets. Then their orbits were modified to be more circular by the gravitational influence of other stars.

    Well, if that can happen to a comet I don’t see any reason why it couldn’t happen to a large terrestrial or small gas giant. It just needed to have been given a more energetic kick, because it’s more massive.

  8. Let’s remember that the Oort cloud itself is yet to be discovered.
    Not a single object with a more or less circular orbit at those distances has been found.
    http://en.wikipedia.org/wiki/Oort_cloud :
    “only four currently known trans-Neptunian objects—90377 Sedna, 2000 CR105, 2006 SQ372, and 2008 KV42—are considered possible members of the inner Oort cloud”
    and these have extremely eccentric orbits, so are problematic.

    1. We can reasonably infer that the oort cloud exists by measuring the number of objects in long period orbits. This comet data is what Matese and Whitmire are trying to extrapolate from. The biggest and most interesting objects discovered to date are Sedna and 2006 SQ372, with the latter being the most interesting. Just for the record I don’t consider this article to be much more than a wild guess, and attempt at fame and posterity if by some slim chance they are right. Nevertheless it is skillful manipulation of the mainstream media, and in this case it should spark the imagination the general public about the WISE mission, which is a good thing.
      To elaborate a bit on my previous comment, what I picture early in the solar system’s development is a small star cluster with the potential for numerous close interactions between stars. The interstellar medium in that early period could very well have been full of well mixed material, some of which exited with Sol as the Oort cloud when it left that cluster of stars.
      If I was back in my educational years, I could use this concept as the basis for several doctoral theses. I would be willing to bet that in a well mixed stellar birth cluster the more massive the central star(s) in a solar system the more likely there will be a captured small star, brown dwarf, or gas giant in very distant orbit. A simple example might be Alpha Centauri which has a yellow dwarf and large orange dwarf for its central mass and a small red dwarf in a very distant orbit. Also I would guess that the mass of any distant object(s) would vary directly with the mass of the central star(s).

  9. I wouldn’t be surprised if there are planets or planemos out there.

    I’m betting that there are far more planemos than stars anyway, especially brown dwarfs and gas giants. Many of these probably formed in star forming regions, but never gained enough mass to sustain fusion. Smaller ones might have been ejected via gravitational interactions during system formations. These objects would be quite difficult to detect.

    1. Difficult to detect – so we could call the Oort cloud population “problemos”, huh?

  10. of course there is a giant planet just outside or near the boundaries of our solar system. NASA says no and say yes later. for example: no water on moon, there is now, no water on mars, there is now, there are no habitable planets other than earth, there are so many now, etc. etc. etc.. they keep on fooling us as though as we are fools.

  11. @ marlon

    Science and discovery can be a painstaking, time-consuming, sometimes indirect process. Apart from that, your post reveals more about you than it does about NASA.

    @ Manu

    Manu says no fact: plenty fact now following: It looks like they will be getting a small reduction in their budget. We will finally know when congress votes on it.

  12. It’s a red dwarf. There I called it first 😛

    To speak from the avid enthusiast yet technically uneducated sector (unless you count the whole Universe series on Netflix plus countless blogs..) on the conspiracy theories ~ Astronomers/physicists are not arguing the fact of there potentially being SOMETHING out there.. But NO they most certainly have NOT found it yet! The reason they are arguing so much is because they want to be credited as the first one to find IT. It’s bs to say data on the comets trajectories are inconclusive because you don’t need that data to prove there is obviously something pulling the outer objects towards a perpendicular ellipses to that of the inner herd and possibly causing the Earth’s wobble, the Sun’s polar flips every 7 years, and made the larger than Neptune object, Uranus, turned up on its side. But alas, you just don’t know what or where it is exactly now yet, do you? Well mark my words ~ it’s a red dwarf but I have no idea whereabouts so I’ll hereby claim myself debunked.

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