Planetkiller Presents New Evidence for “Planet X”

Is there a "dark Neptune" lurking at the extreme edge of the Solar System?
Is there a dark, massive “Planet Nine” lurking at the extreme edge of the Solar System?

A planet-killing astronomer is now attempting to introduce a new world into the Solar System.

Self-professed “Pluto killer” Mike Brown — the Caltech professor and astronomer whose discovery of Eris in 2005 prompted the reclassification of what constitutes a full-fledged planet, thus knocking Pluto from the list a year later — is now offering up evidence for the existence of a “real” ninth planet, far beyond the orbit of Pluto and possibly even traveling farther than the Kuiper Belt extends. This “Planet Nine,” say Brown and co-researcher Konstantin Batygin — also of Caltech — could be nearly the mass of Neptune, although it has not been directly observed by any Solar System surveys performed to date.

(And for those long-time Planet X fans who will assuredly cry “told you so,” this hypothesis is based on actual observations and not just wishful thinking or sci-fi dreams. There’s a difference.)

Pluto is not the last world in the Solar System, not by a long shot. Beyond it within the Kuiper Belt exist many icy objects, some of similar size, countless others — i.e., trillions – much smaller, down to comet- and asteroid-sized. (And then of course there’s the Oort Cloud even farther out but we’re not going there.)

Observations of the orbits of a dozen of the larger recently-discovered worlds beyond Pluto, including Sedna (also discovered by Mike Brown) point to the presence of an as-yet unseen and massive object that appears to be concentrating their perihelia — that is, their closest approach points to the Sun – near a similar region. (Keep in mind that KBOs — like Pluto — tend to have highly-inclined and eccentric orbits; they aren’t aligned in a neat plane circling the Sun like the other planets… more on that here.) Brown and Batygin noticed when they reach their perihelia they all pass through the ecliptic — from south to north too — and that’s not likely just a coincidence. Something may be gravitationally shepherding the group of KBOs, and the astronomers’ models appear to implicate a ninth planet.

This incredibly distant (and apparently cold and dark) world, possibly kicked out of the planetary neighborhood just a few million years after the formation of the Solar System, would travel around the Sun in a 10,000–20,000-year-long orbit that takes it no closer than 200 A.U. (more than 4 times farther than Pluto) and as far away as 1,200 A.U.

Observations of KBO orbits point to the presence of a Neptune-mass object that orbits far beyond the Sun (K. Batygin and M. E. Brown Astronom. J. 151, 22 (2016))
Observations of several KBO orbits point to the presence of a Neptune-like (or super-Earth) object far beyond the Sun. The small green circle is the diameter of the Kuiper Belt. (K. Batygin and M. E. Brown Astronom. J. 151, 22 (2016). Source: Nature)

Some astronomers aren’t ready to make the same conclusions, though. “I worry that the finding of a single new object that is not in the group would destroy the whole edifice,” said UCLA’s David Jewitt, who discovered the Kuiper Belt. “It’s a game of sticks with only six sticks.”

But Brown, in typical Plutokiller fashion, is overtly confident in the research.

“If you say, ‘We have evidence for Planet X,’ almost any astronomer will say, ‘This again? These guys are clearly crazy.’ I would, too,” Brown said. “Why is this different? This is different because this time we’re right.” (Source)

That would mean, if Brown and Batygin are indeed right, that they have discovered a new planet and that would be huge (pun intended.) But that would be something that any (every?) astronomer would love to have to his or her namesake, so one could assume a tiny bit of confidence bias. 🙂

“This would be a real ninth planet. There have only been two true planets discovered since ancient times, and this would be a third. It’s a pretty substantial chunk of our solar system that’s still out there to be found, which is pretty exciting.”
— Mike Brown, Richard and Barbara Rosenberg Professor of Planetary Astronomy at Caltech

That’s the news in a nutshell; I haven’t read the actual findings or attempted to go over the math myself (not that that would have done me or anyone any good – trust me.) Whether or not this pans out into something real or turns into just the latest “Search for Planet X” story remains to be seen. Further observations and analysis will be needed — some using existing data, some with telescopes that haven’t even been completed yet — to confirm these findings one way or the other. But, of course, that’s exactly how science works! You can be sure there’ll be more to come.

Read more detailed analysis by Eric Hand on Science and Alexandra Witze on Nature, and see the Caltech release here.

The findings were published today, Jan. 20, 2016, in the Astrophysical Journal.

UPDATE 1/21: Brown and Batygin have started a blog called Find Planet Nine, wherein they discuss their findings and how the astronomical population can help hunt for the purported planet. Check it out here.

UPDATE 1/22: Astrophysicist Ethan Siegel discusses why he remains skeptical about these new planetary claims on his blog at


  1. I am bookmarking this so I can come back (when I’m not working and about to head off to a very important meeting) to read the articles/posts you linked to. This qualifies as meeting prep right? 😉


    1. Jason Major says:

      Most definitely qualifies!

      Liked by 1 person

      1. 🙂 so glad it does!

        Liked by 1 person

  2. There are parallels to Neptune here — mathematically calculated and then observers went out and found it. Planet Nine, if it exists, would be far more difficult; in the CalTech press release, it was said that the proposed planet could be anywhere in its orbit and if it is near aphelion, only a couple of telescopes are big enough to be able to see it. But if it is near perihelion, it may already be there on existing surveys.


    1. Jason Major says:

      It will be tricky; even though it’s a “whole planet” based on the calculations, if it’s there it may be too distant and small for current scopes. But at least we can figure out where to look, which will help tremendously. As they say, “absence of evidence is not evidence of absence!”


      1. Unless the planet is actually found, it is a hypothesis, albeit an interesting one and one worth pursuing considering the bona fides of the scientists putting it forth.


  3. Bostjan says:

    i am a bit sad around the issue. Not because it might be true, but because dr. Brown was up till december quite dismissive and arrogant about a possible 9th planet issue, in regards the findings presented from a team of scientists from Sweden – Mexico, due to findings of alma telescope from Chile. And yet, now they are professing the issue as their finding in the major media…Ah, these scientists….


    1. Having just read the linked article, Dr. Brown was skeptical about the specific claim, and he seems to have had much company in that:

      “According to Scott Sheppard, a planetary scientist at the Carnegie Institution for Science involved with surveys of the outer solar system, the fact that only two observations apiece underpin both discovery claims makes them hard to swallow.” Dr. Brown was also quoted as saying that he was open to the idea of a large outer planet beyond the Kuiper Belt. So not actually inconsistent.

      At bottom, perhaps any change in attitude is a matter of having better data. That is how science works — if new data leads to a different conclusion, then you change your ideas.

      Liked by 2 people

      1. Bostjan says:

        Thanks for the thougthfull reply. Nevertheless, the way i see it, dr. Brown is prone to jokes- naming himself ”pluto killer” is one of them. A month and a half is not really much in terms of scientific modeling, i simply do not believe that the last month was his breakthrough in regards the theoretical model he concluded with partners at Caltech. The way I see it, he simply bandwagoned, at first he ridiculed the data from chile observatory, then within month Caltech comes with its model…it is quite prozaic from my point of view…and it is also the way the battle on the scientific grounds is done in regards who will be the one that will win the game of new discovery… nothing new here really either…


  4. zperryd says:

    Awesome read! Very interesting stuff.
    “This is different because this time we’re right” – Love it!


  5. Mr. Hematite says:

    Fascinating piece of astronomy. The text books could be rewritten again! I for one hope he’s right but will remain skeptical until it’s conclusive.


  6. It is definitely a remarkable discover, however, I don’t see the point talking about NASA, to spend so much resources on space adventures. I don’t think it will amount to anything much.


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