Planetary Society - Evidence for an Undiscovered Super-Earth at the Edge of Our Solar System
Anyone here disappointed when Pluto got demoted? Well as Emily Lakdawalla at the Planetary Society points out, there’s now evidence that there maybe a ninth (non dwarf) planet out there in the distant edges of the solar system. The evidence is far from conclusive, but we may get to add another member to our sun’s planetary family.
We still don’t know for sure if it’s out there, but it’s looking likelier that there is an undiscovered planet orbiting beyond the Kuiper belt. If it’s there, it’s big, far, and slow. It would be roughly 10 times the mass of Earth (or about half the mass of Neptune), likely never gets closer to the Sun than about 100 200 AU, and takes more than 10,000 years to orbit the Sun. The presence of such a planet would explain two odd clusters of Kuiper belt orbits, including distant detached objects Sedna and 2012 VP113, and the perpendicularly tilted ones of several newly discovered small worlds.
The potential ninth planet is described in a paper written by Konstantin Batygin and Mike Brown that provides a theoretical explanation for how such a distant planet could perturb the Kuiper belt object orbits into their present shapes, sizes, and orientations. You can read a preprint of the Batygin and Brown paper here, and an excellent Caltech press release about the Batygin and Brown work here. The two have also launched a blog, findplanetnine, in which they’re chronicling their efforts to search for this undiscovered object. Batygin and Brown explain what they’re proposing: