Strange orbits of distant space rocks have been used to infer that the solar system has an unseen ninth planet, but those orbits may be less strange than we thought, meaning there is no need for a new planet
Source:
https://www.newscientist.com/article/2241222-mysterious-planet-nine-on-the-solar-systems-edge-may-not-be-real/?utm_campaign=RSS%7CNSNS&utm_source=NSNS&utm_medium=RSS&utm_content=home