A small team of planetary scientists from the California Institute of Technology, Université Côte d'Azur and Southwest Research Institute reports possible new evidence of Planet 9. They have published their paper on the arXiv preprint server, and it has been accepted for publication in The Astrophysical Journal Letters.
By all rights it should be planet 10. Pluto got shafted.
If Pluto (and others like it) were a planet, then it would be Planet 238 or something.
Is Luna, our moon, a planet?