Because it's not one and really cannot be a planet!
the only planet that scientists do not consider a planet is Pluto, (but they also found new planets in the asteroid belt.)Pluto
I think tier is 11 planet
No
No, the moon is not a planet. It is earth's natural satellite.
Ceres, Pluto, Haumea, Makemake and Eris.
earth is considered as a planet because it is a part of solar system
Pluto, but some consider that Pluto is not a planet anymore.
August 24, 2006 is the date when Pluto was consider no more a planet.
Because it is not big enough. It is classed as a dwarf planet.
Since 2006, Pluto has been considered a dwarf planet.
2006
A VERY small planet.