Actually planet doesn’t have any hard set definition, we kind of just do it case by case because its damn near impossible to come up with a rigid definition that doesn’t suddenly classify some planets as moons or some moons as planets or create weird situations in which an object can switch between the two.
It has been argued that the definition is problematic because it depends on the location of the body: if a Mars-sized body were discovered in the inner Oort cloud, it would not have enough mass to clear out a neighbourhood that size and meet criterion 3. The requirement for hydrostatic equilibrium (criterion 2) is also universally treated loosely as simply a requirement for roundedness; Mercury is not actually in hydrostatic equilibrium, but is explicitly included by the IAU definition as a planet
Actually planet doesn’t have any hard set definition, we kind of just do it case by case because its damn near impossible to come up with a rigid definition that doesn’t suddenly classify some planets as moons or some moons as planets or create weird situations in which an object can switch between the two.
https://en.wikipedia.org/wiki/IAU_definition_of_planet
And in that same article: