Planet Nine and inclination, of objects scattered outward by Jupiter and Saturn, leaving some of them in high inclination (inc > 50°), low eccentricity orbits which have not been observed. The gravitational influence of Planet Nine would explain five peculiarities of the Solar System: While other mechanisms have been offered for many of these peculiarities, the gravitational influence of Planet Nine is the only one that explains all five. The gravity of Planet Nine also excites the inclinations of scattered disc objects, which in numerical simulations leaves the short-period comets with a broader inclination distribution than is observed. The clustering of the
Definition of planet spherical under its own gravity but not large enough to fuse. This definition would add 19 moons to the list of planets in our Solar System. The discovery since 1992 of extrasolar planets, or planet-sized objects around other stars ( such planets in planetary systems including multiple planetary systems as of ), has widened the debate on the nature of planethood in unexpected ways. Many of these planets are of considerable size, approaching the mass of small stars, while many newly discovered brown dwarfs are, conversely, small enough to be considered planets. The material difference between a low-mass star and