http://www.newsweek.com/planet-9-scientists-have-new-theory-about-mysterious-objects-outer-solar-962132

The outer solar system is a weird place full of weird things displaying weird behavior. Scientists are still trying to figure out how all those mysteries have fit together, leading to hypotheses like the existence of a so-called Planet 9 wreaking havoc on otherwise orderly orbits.

But one key piece of the outer solar system puzzle doesn't need a ninth planet to make the numbers work, according to research presented at the annual conference of the American Astronomical Society being held this week in Denver. (That doesn't mean it proves Planet 9 doesn't exist, however.)