Here's why:
* The IAU definition of a planet: To be considered a planet, a celestial body must:
* Orbit the Sun.
* Have enough gravity to be round.
* Have cleared its neighborhood of other objects.
* Pluto's failure to meet the third criteria: Pluto shares its orbit with a large number of other icy bodies in the Kuiper Belt. This means it hasn't cleared its orbital path, a defining characteristic of planets.
The reclassification of Pluto was a controversial one, but it was based on the need for a scientifically sound definition of "planet."
While Pluto may not be a planet anymore, it remains a fascinating and important object in our solar system.
