Here's why:
* Gravity is a property of all objects with mass. Even you have gravity!
* Pluto has enough gravity to be round. This is one of the key characteristics of a planet.
* The main reason Pluto is a dwarf planet is because it hasn't cleared its orbital neighborhood. This means there are other objects of comparable size sharing its orbital path.
In essence, Pluto is considered a dwarf planet because it doesn't fit the definition of a full-fledged planet, which requires an object to dominate its orbital region.
