“Size is not the reason Pluto was demoted.”
?
Is Pluto a planet? Does it qualify? For an object to be a planet, it needs to meet these three requirements defined by the IAU:
•It needs to be in orbit around the Sun – Yes, so maybe Pluto is a planet.
•It needs to have enough gravity to pull itself into a spherical shape – Pluto…check
•It needs to have “cleared the neighborhood” of its orbit – Uh oh. Here’s the rule breaker. According to this, Pluto is not a planet.
https://www.universetoday.com/13573/why-pluto-is-no-longer-a-planet/