Why Pluto is not a planet? What rules does it not follow?
According to new rules adopted by the International Astronomical Union, a celestial body must meet the following criteria in order to qualify as a planet:
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.