Some of the objects may crash into the planet, others may become moons. Pluto follows the first two rules: It is round, and it orbits the sun. It does not, however, follow the third rule. It has not yet cleared the neighborhood of its orbit in space. Because it does not follow this rule, Pluto is no longer considered a planet. read more
Pluto is not considered a planet anymore because The International Astronomical Union (IAU) voted on their first official definition of a planet, and this definition does not fit for Pluto. Scientists recognized that Pluto was really one of many dwarf planets from the Kuiper Belt. read more