This announcement was made by Cornell University in 2010, however there is still a lot of discussion taking place behind the scenes. The site "Nasa Spaceflight" has quite a lengthy forum taking place on the topic.
Here is the release from Cornell:
We present an updated dynamical and statistical analysis of outer Oort cloud cometary evidence suggesting the sun has a wide-binary Jovian mass companion. The results support a conjecture that there exists a companion of mass ~ 1-4 M_Jup orbiting in the innermost region of the outer Oort cloud. Our most restrictive prediction is that the orientation angles of the orbit normal in galactic coordinates are centered on the galactic longitude of the ascending node Omega = 319 degree and the galactic inclination i = 103 degree (or the opposite direction) with an uncertainty in the normal direction subtending ~ 2% of the sky. A Bayesian statistical analysis suggests that the probability of the companion hypothesis is comparable to or greater than the probability of the null hypothesis of a statistical fluke. Such a companion could also have produced the detached Kuiper Belt object Sedna. The putative companion could be easily detected by the recently launched Wide-field Infrared Survey Explorer (WISE).
|Comments:||41 pages, 9 figures, submitted to ICARUS|
|Subjects:||Earth and Planetary Astrophysics (astro-ph.EP)|
|Cite as:||arXiv:1004.4584v1 [astro-ph.EP]|
Another Planet-9 resurrection. It seems that several are in the Kuiper Belt. They have at least 1 candidate found. I am posting the link to the short article. Yes, it is a very large planet.