Kathryn Volk and Renu Malhotra at the University of Arizona have noticed some strange movement out in the Kuiper belt…movement that they believe could suggest the existence of a tenth planet. ... Objects in the Kuiper belt are far enough away from the other major bodies in our solar system that the gravitational influence of the large planets doesn’t impact them (at least, not to a measurable degree); however, their movements can still be predicted, thanks to sky surveys and a host of advanced technologies. The search for Planet Nine has lead scientists to believe that it is orbiting around...