Massive Planet X Now Urgently Sought by Top Planet-Hunters

We seem to be getting very close now to a discovery of a massive Planet X in the outer solar system.  I heard this report on the evening BBC news, a slot which indicates the seriousness with which this subject is now being taken by the scientific community:

“American astronomers say they have strong evidence that there is a ninth planet in our Solar System orbiting far beyond even the dwarf world Pluto.  The team, from the California Institute of Technology (Caltech), has no direct observations to confirm its presence just yet.  Rather, the scientists make the claim based on the way other far-flung objects are seen to move.  But if correct, the putative planet would have 10 times the mass of Earth.

“The Caltech astronomers have a vague idea where it ought to be on the sky, and their work is sure to fire a campaign to try to track it down.  “There are many telescopes on the Earth that actually have a chance of being able to find it,” said Dr Mike Brown.  “And I’m really hoping that as we announce this, people start a worldwide search to go find this ninth planet.”

The group’s calculations suggest the object orbits 20 times farther from the Sun on average than does the eighth – and currently outermost – planet, Neptune, which moves about 4.5 billion km from our star.  But unlike the near-circular paths traced by the main planets, this novel object would be in a highly elliptical trajectory, taking between 10,000 and 20,000 years to complete one full lap around the Sun.” (1)

Dr Mike Brown is a premier academic planet-hunter, and for him to make this public pronouncement is quite unprecedented.  One can only assume that his team have experienced a leak of their information, nudging him to go public with a paper in the Astronomical Journal (2).  After all, it is only one month since similar speculation – that time by scientists working at the large array at Atacama in Chile – was widely criticised by astronomers for being presumptuous (3).   Why risk similar criticism if they’re not sure of what they’re proposing?  There is clearly heightened excitement going on at the moment, with the stakes running very high indeed.  Here’s what Dr Mike Brown said last month about the two proposals put forward by the Atacama teams:

“Mike Brown, a prominent California Institute of Technology astronomer and self-described “Pluto killer” who discovered several large TNOs that dethroned the former planet, unleashed another statistical argument against the claimed new planets on Twitter. “If it is true that ALMA accidentally discovered a massive outer solar system object in its tiny, tiny, tiny, field of view,” Brown tweeted, “that would suggest that there are something like 200,000 Earth-sized planets in the outer solar system. Which, um, no. 

“”Even better,” he added later, “I just realized that this many Earth-sized planets existing would destabilize the entire solar system and we would all die.” That said, Brown notes, “the idea that there might be large planets lurking in the outer solar system is perfectly plausible.”” (4)

So, whilst acknowledging the real potential for the presence of undiscovered large planets out there, he was sceptical that the Atacama team had been lucky enough to stumble upon such an object given the tiny fields of view they were studying when they picked these blips up.  It is now clear that he has been on the hunt for this object himself for some time.

Dr Brown’s interest lies in the anomalous movements of the extended scattered disk objects lying just beyond the Kuiper Belt, as well as non-random clustering of some of the KBOs themselves (2).  I would hazard a guess that as more of these objects are verified (many by his team, no doubt) an increasingly discernible pattern is emerging, suggestive of the presence of a large planet.  That work is clearly on-going:

“Continued analysis of both distant and highly inclined outer solar system objects provides the opportunity for testing our hypothesis as well as further constraining the orbital elements and mass of the distant planet.” (2)

He seems to have an idea of where this ‘Planet Nine’, as he’s calling it, is located; how big it is; how long it takes to move around the Sun (in it’s “highly elliptical orbit”), and how far away it lies. 

Dr Brown has been working closely with dynamicist Dr Konstantin Batygin for some time on this Planet X puzzle, according to the Caltech press release:

“”Although we were initially quite skeptical that this planet could exist, as we continued to investigate its orbit and what it would mean for the outer solar system, we become increasingly convinced that it is out there,” says Batygin, an assistant professor of planetary science. “For the first time in over 150 years, there is solid evidence that the solar system’s planetary census is incomplete.”

“…Batygin and Brown realized that the six most distant objects from [Chad] Trujillo and [Scott] Shepherd’s original collection [of distant KBOs] all follow elliptical orbits that point in the same direction in physical space. That is particularly surprising because the outermost points of their orbits move around the solar system, and they travel at different rates.

“It’s almost like having six hands on a clock all moving at different rates, and when you happen to look up, they’re all in exactly the same place,” says Brown. The odds of having that happen are something like 1 in 100, he says. But on top of that, the orbits of the six objects are also all tilted in the same way—pointing about 30 degrees downward in the same direction relative to the plane of the eight known planets. The probability of that happening is about 0.007 percent. “Basically it shouldn’t happen randomly,” Brown says. “So we thought something else must be shaping these orbits.”" (5)

Some of this data will sound eerily reminiscent of Zecharia Sitchin’s work (6) – particularly the 30 degree downward tilt of the undiscovered planet’s gravitational influence.  It’s highly elliptical.  It’s at least ten times the Earth’s mass, they think (2).  It’s located about 600 Astronomical Units away, they think, with an orbit of tens of thousands of years – more like my own conclusions some years ago, as I came to realise that Sitchin’s assumption of a 3600 year orbit was likely far too small a figure (7).

How easy this object will be to discover depends very much upon what point of its orbit it currently resides in.  If near perihelion, then there are a great many telescopes on the Earth capable of discovering it.  If, however, it is nearer its furthest point, or aphelion, then only the world’s largest telescopes, such as the twin 10-meter telescopes at the W. M. Keck Observatory and the Subaru Telescope, all on Mauna Kea in Hawaii, will be capable of detecting it.  Dr Brown hopes that an early release of this work will propel the scientific telescope-wielding community into action.  I suspect he figures that his top reputation as arch-planet-hunter will prevent him from being roundly trashed by his peers, as happened to the Atacama scientists last month.  Not only that, but this proposal ticks an awful lot of ‘Nibiru’ boxes, which will bring a lot of public interest to bear on this unfolding science.

But why has this object so far evaded detection?  Why didn’t the infra-red sky survey WISE discover Planet Nine?  After all, it’s very substantial indeed, and relatively close (lying in the gap between the Kuiper Belt and the inner Oort Cloud).  That’s a critical issue here, as the scientists working on the WISE data seemed to rule this possibility out in no uncertain terms, declaring that no Saturn-sized planet could be lurking within 10,000 AU (8).  By contrast, Planet Nine may be a mere 600 AU, or less, albeit much smaller than Saturn by Batygin and Brown’s reckoning.  Even so, surely WISE should have spotted it?

So what’s the chances of finding it soon?  As more data rolls in, Dr Batygin and Dr Brown seem to be honing in on this object, the parameters of its position, mass and orbits narrowing all the while.  At the moment, they are still playing with a wide range of values, and conducting the astrophysical equivalent of war-games with them.  There are no suggested coordinates for its position, or even a vague suggestion of its rough whereabouts for the world’s top observatories to work with.

Their model does throw up some intriguing predictions, which may help them to find this Planet Nine perturber indirectly:

“A unique prediction that arises within the context of our resonant coupling model is that the perturber allows for the existence of an additional population of high-perihelion KBOs that do not exhibit the same type of orbital clustering as the identified objects. Observational efforts aimed at discovering such objects, as well as directly detecting the distant perturber itself constitute the best path toward testing our hypothesis.” (2)

So, it’s not just the proverbial smoking gun they seek, but also some accompanying high-inclination grapeshot.  And perhaps that’s what they’re hoping the observatories will discover, expanding their data set substantially.

In terms of the origin of this distant object, the authors think that Planet Nine may have started out as a gas giant core among the ice giants Uranus and Neptune, before being scattered from this zone by the ‘gaseous component of the [primordial] nebula’.  But, at the same time, they don’t seem to entirely rule out a much larger object than 10 Earth masses, particularly if the orbit is highly eccentric:

“Having identified an illustrative set of orbital properties of the perturber in the planar case, we demonstrated that an inclined object with similar parameters can dynamically carve a population of particles that is confined both apsidally and nodally. Such sculpting leads to a family of orbits that is clustered in physical space, in agreement with the data. Although the model proposed herein is characterized by a multitude of quantities that are inherently degenerate with respect to one another, our calculations suggest that a perturber on an a’ ~ 700 AU, e’ ~ 0.6 orbit would have to be somewhat more massive (e.g., a factor of a few) than m’ = 10 ME to produce the desired effect.” (2)

That, for me, is where things may yet get very interesting indeed!  We could find that this object is substantially greater in mass than a ‘Super-Earth’, but is instead a compact gas giant – my ‘Dark Star’.  I’ve always thought that this object would be found in a highly elliptical orbit sweeping through the zone between the Kuiper Belt and the inner Oort Cloud.  After all, that would make sense of why that area is largely devoid of material.  That judgement seems to correlate reasonably well with the results emerging from this latest scientific study.  Ten Earth masses is a minimum, it seems, and could stretch to a much larger object if it’s current position lies near aphelion (maybe 1000 AU out?) and if it’s orbit is highly eccentric (likely).

The burning question for me is why didn’t the infra-red sky search WISE detect it? It should be eminently detectable at the sort of distances we’re discussing. Either way, the indirect evidence is becoming compelling, and I think that the discovery of this object is now within sight.  It may not turn out to be quite what Zecharia Sitchin had in mind.  It’s orbit will be tens of thousands of years, not 3600 (which, I think, was an educated guess on his part).  It may no longer penetrate the planetary zone during its perihelion transit, but instead sweep through the massive gap between the Kuiper Belt and the inner Oort Cloud in its highly inclined, highly eccentric elliptical orbit.  It may be a gaseous world with it’s own ‘system’ of planets/moons.  Depending on its size, it may qualify as an ultra cool ‘Dark Star’.  But even if this is the case, Sitchin’s general thrust about a mythical Planet X object may turn out to be right after all.  If it quacks like a duck, and walks like a duck… well, you get the picture.