More Evidence for Planet Nine

One of the pair of Caltech scientists who announced in January that there was a very high probability that a ‘super-Earth’, dubbed ‘Planet Nine’, exists beyond Neptune (1,2), has noted that a newly discovered eccentric Kuiper Belt Object cuts down the possibility that they were wrong still further.

“The object [uo3L91] shares some of the same behavior as the other six Kuiper Belt bodies, suggesting it has also been pushed by a large planet that is between 200 and 1,200 times the distance from the Sun to Earth. The object was discovered by the Canada France Hawaii Telescope, which is conducting the Outer Solar System Origins Survey (OSSOS); information about its movements were presented recently by astronomer Michele Bannister at the SETI Institute.” (3)

An Artist's impression of Planet Nine. Image credit: Caltech/R. Hurt (IPAC)

An Artist’s impression of Planet Nine. Image credit: Caltech/R. Hurt (IPAC)

Dr Mike Brown was straight off the marks with this latest discovery’s potential tie-in with his proposed Planet Nine body, publically offering it as possible evidence before going through the usual peer-review process (4). The discovery of one more extended scattered disk object showing the same sort of collective properties as the initial cluster of six studied by Drs Batygin and Brown may not seem too exciting on the face of it, but it goes a long way towards answering the following scholarly criticism of their initial proposal:

“Others, like planetary scientist Dave Jewitt, who discovered the Kuiper belt, are more cautious. The 0.007% chance that the clustering of the six objects is coincidental gives the planet claim a statistical significance of 3.8 sigma—beyond the 3-sigma threshold typically required to be taken seriously, but short of the 5 sigma that is sometimes used in fields like particle physics. That worries Jewitt, who has seen plenty of 3-sigma results disappear before. By reducing the dozen objects examined by Sheppard and Trujillo to six for their analysis, Batygin and Brown weakened their claim, he says. “I worry that the finding of a single new object that is not in the group would destroy the whole edifice,” says Jewitt, who is at UC Los Angeles. “It’s a game of sticks with only six sticks.”” (5)

Now it’s a game with seven sticks, it seems. Mike Brown thinks that this lowers the possibility of this statistical clustering being ‘a fluke’ to vanishingly low levels, as he described on his Twitter feed:

“I haven’t done the statistics yet, but I suspect this takes the probability of this being a statistical fluke down to ~.001% or so.” (6)


Meanwhile, one of the original progenitors of the Nemesis’ theory from back in the 1980s, Daniel Whitmire, has mooted the possibility that Planet Nine might be the cause of periodic mass extinction events on Earth:

“Whitemire (sic) and [Professor John] Matese’s theory is that as Planet X orbits the sun, its tilted orbit slowly rotates and Planet X passes through the Kuiper belt of comets every 27 million years, knocking comets into the inner solar system. The dislodged comets not only smash into the Earth, they also disintegrate in the inner solar system as they get nearer to the sun, reducing the amount of sunlight that reaches the Earth. In 1985, a look at the paleontological record supported the idea of regular comet showers dating back 250 million years. Newer research shows evidence of such events dating as far back as 500 million years.” (7)

Dr. Whitmire’s original work concentrated on the existence of a multiple Jupiter-mass object lying in the very outer reaches of the solar system which affected comets in the outer Oort Cloud, sending periodic showers down towards the central solar system (8). We might call such an object a sub-brown dwarf these days, or perhaps a ‘Class Y Ultra-Cool Brown Dwarf’, in astronomical parlance (9). It’s the object I believe to exist, too – an object I call the Dark Star. I think it’s much closer than the Nemesis theory originally described, and that there may be good reason to believe that the presence of this object is obscured by a dusty nebula, preventing clear detection in visible or infra-red light (10,11).


Personally, I think there may be a multitude of bodies out there in the outer solar system, as per the ideas put forward by Eugene Chiang, an astronomer at the University of California, Berkeley back in 2005 (12), in response to the discoveries of various Kuiper belt Objects. His thoughts echo those of Alan Stern, of the Southwest Research Institute in Boulder, Colorado back in 2002 (13). Chiang’s concept of large-scale planetary migration early in the solar system’s history seems appealing, suggesting not just a Planet Nine, a Planet X, but also Planets XI, XII, XIII etc:

“The oligarch theory of planet formation states that there were hundreds of planet-sized objects, known as oligarchs, in the early stages of the Solar System’s evolution. In 2005, astronomer Eugene Chiang speculated that although some of these oligarchs became the planets we know today, most would have been flung outward by gravitational interactions. Some may have escaped the Solar System altogether to become free-floating planets, whereas others would be orbiting in a halo around the Solar System, with orbital periods of millions of years. This halo would lie at between 1,000 and 10,000 AU from the Sun, or between a third and a thirtieth the distance to the Oort cloud.” (14)

And yet, there does not appear to be a continuum of objects from the Kuiper Belt out towards the inner Oort Cloud, but rather a long gap punctuated by the extended scattered disk objects so tantalisingly suggestive of a distant Planet X object. This ‘Kuiper Cliff’ suggests that something, probably Planet Nine in whatever guise it eventually makes itself known, has swept out the gap, and laid claim on this territory all for itself. Note, this, from back in 2002:

“”There’s something funny going on out there.” Marc Buie of the Lowell Observatory in Arizona is talking about a strange feature at the far edge of our solar system beyond Pluto, among the swarm of small worlds called the Kuiper Belt. It’s a wild, uncharted place out there, teeming with icy celestial bodies that may give us essential clues to how the planets formed. It may even be a breeding ground for life. But what’s intriguing Buie at the moment is the very edge, about 50 times further out from the Sun than the Earth’s orbit. Here, at the “Kuiper Cliff”, the number of astronomical objects drops off precipitously. Buie won’t be drawn too far but, when pressed, he speaks of the possibility that some “massive object” has swept the zone clean of debris…” (15)

Such thinking would seem to support Daniel Whitmire’s claim that a Planet X body might periodically graze the outer edge of the Kuiper Belt, occasionally sending showers of objects in all directions whilst shaping that very belt.

However, the fact is, we still don’t really understand what’s out there beyond the Kuiper Belt. Science goes through phases of favouring various hypotheses, and until the last couple of decades or so was pretty much set on destroying the very concept of Planet X, and all who foolishly were to associate themselves with it. The ‘belief’ that a Planet X body might exist was confined to the fringes. Planets couldn’t be found out there, it was declared, because theory of solar system planet formation simply wouldn’t allow for it, and previously declared anomalies could be explained away (16).

With the discoveries of anomalous extended Kuiper Belt Objects, that thinking has gradually changed, to the point now where the scientific community is broadly expectant of a major planetary discovery in the next few years. But I think it’s worth noting that whatever that discovery might bring, it doesn’t mean that that’s necessarily the end of the hunt for new planets in the outer solar system. Indeed, breaking through that initial scientific taboo opens up the field to all manner of possibilities.

Written by

31st March 2016


1) Andy Lloyd “Massive Planet X Now Urgently Sought by Top Planet-Hunters” 20th – 23rd January 2016

2) K. Batygin & M. Brown “Evidence for a Distant Giant Planet in the Solar System” 20th January 2016, The Astronomical Journal, Volume 151, Number 2,

3) Loren Grush “Scientist claims there’s even more evidence of Planet Nine’s existence” 25th March 2016 with thanks to Eitan

4) Andrew Griffin “Planet Nine: Scientists find more evidence that hidden planet is sitting at the edge of our solar system” 27 March 2016, with thanks to Lee

5) Eric Hand “Astronomers say a Neptune-sized planet lurks beyond Pluto” 20th June 2016 with thanks to Lee

6) Dr Mike Brown, 24th March 2016,

7) Bob Whitby “Researcher links mass extinctions to ‘Planet X'” 30th March 2016 with thanks to Jim

8) D. Whitmire & A. Jackson “Are periodic mass extinctions driven by a distant solar companion?”. Nature, 1984, 308 (5961): 713–715. doi:10.1038/308713a0

9) “Astronomy & Cosmology – Stars – Stellar Classes: Type L, T & Y Cool Brown Dwarf Stars”

10) Andy Lloyd “The Shroud Hypothesis as part of a Dark Star Solution” 9th February 2016

11) Andy Lloyd “The Cumulative Effect of Intermittent Interstellar Medium Inundation Upon Objects In The Outer Solar System” 02/2016, DOI: 10.13140/RG.2.1.5112.5526

12) New Scientist “Far-out worlds, just waiting to be found” 23rd July 2005, issue 2509,

13) Andy Lloyd “Planet X is sweeping out the Kuiper Belt – Official!” December 2002

14) “Planets beyond Neptune”

15) H. Couper & N. Henbest “The Hunt for Planet X” New Scientist, pp30-4, 14th December 2002

16) Myles Standish “Planet X – No dynamical evidence in the optical observations” 16th July 1992, Astronomical Journal 105 (5): 200–2006. Bibcode:1993AJ….105.2000S.

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