Why is Pluto no longer considered a planet?
Since 2006, Pluto was classified as "minor planets and asteroids”.
Scientists were forced to revise the classification by the discovery of Ceres and Eris. They, like Pluto, have not yet cleared their orbit of extraneous celestial bodies. In addition, Pluto cannot be considered the most massive body in its neighborhood.
Therefore, despite the presence of an atmosphere and its own satellite, it is still not considered the ninth planet.