Question

why, the pluto is not one of the eight planets of solar system .

Answer 1

We called celestial body a planet if:

-It orbits around the Sun;

-It has sufficient mass for its own gravity to achieve hydrostatic equilibrium (nearly round) shape;

-It is dominant in its orbit.




Pluto does not meet one of the criteria of the this definition of a planet: the mass of the objects that has the same orbit that are not his satellites is too large compared to the mass of Pluto, to assume that it dominates