Recent updates on the Search for Planet Nine

It’s a year since proposed the existence of Planet Nine (1).  Despite the fact that its discovery remains elusive, there have been a great many academic papers written on the subject, and no shortage of serious researchers underpinning the theoretical concepts supporting its existence.  Many have sought evidence in the solar system which indirectly points to the perturbing influence of this mysterious world; others have provided data which have helped to constrain the parameters of its orbit (by effectively demonstrating where it could NOT be).  Throughout 2016, I have been highlighting these developments on the Dark Star Blog.


At the close of 2016, two further papers were published about Planet Nine.  The first of these delves more deeply into the possibility that Planet Nine (Brown’s new name for Planet X, which seems to have caught on among astronomers keen to distance this serious search from, well, the mythological planet Nibiru) has a resonance relationship with some of the objects beyond the Edgeworth-Kuiper Belt which it is perturbing.  These kinds of resonance relationships are not unusual in planetary orbital dynamics, so such a suggestion is not that odd, even given the eccentricities of the bodies involved here.  The new research, from the University of California, Santa Cruz, bolsters the case for this kind of pattern applying to Planet Nine’s orbit:

“We extend these investigations by exploring the suggestion of Malhotra et al. (2016) (2) that Planet Nine is in small integer ratio mean-motion resonances (MMRs) with several of the most distant KBOs. We show that the observed KBO semi-major axes present a set of commensurabilities with an unseen planet at ~654 AU (P~16,725 yr) that has a greater than 98% chance of stemming from a sequence of MMRs rather than from a random distribution.” (3)

Their randomised ‘Monte Carlo’ calculations provide a best fit with a planet of between 6 and 12 Earth masses, whose eccentric orbit is inclined to the ecliptic by about 30 degrees.  They are unable to point to a specific area of the sky to search, but provide a broad-brush region which they favour as most probable.  Dr Millholland has also helpfully provided a 3D manipulable 3D figure of the cluster of extended scattered disk objects allegedly affected by the purported Planet Nine, alongside their extrapolated orbit for it (4).  Read More…

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Niku, Drac and L91 Perturbed by Planet Nine…or Something Else?

Dr Konstantin Batygin and Dr Mike Brown argue in their latest paper that the retrograde Kuiper Belt Objects Niku and Drac could have once been extended scattered disk objects (1).  If you have been following these blogs during 2016, it will come as no surprise to you to hear that the influence which perturbed them into their anomalous current orbits was Planet Nine, the 10+Earth-mass planet lurking several hundred-plus Astronomical Units away, whose gravitational influence seems to be influencing the objects in and beyond the Kuiper Belt beyond Neptune (2):

“Adopting the same parameters for Planet Nine as those previously invoked to explain the clustering of distant Kuiper belt orbits in physical space, we carry out a series of numerical experiments which elucidate the physical process though which highly inclined Kuiper belt objects with semi-major axes smaller than a < 100 AU are generated. The identified dynamical pathway demonstrates that enigmatic members of the Kuiper belt such as Drac and Niku are derived from the extended scattered disk of the solar system.” (1) Read More…

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