I think “Planet” should be a gravitationally rounded mass that’s not a star anyway. Those can be divided into rocky and gaseous, and further divided by principal composition.
Smaller than that isn’t usually worth having a name, but moons can be just as interesting as free orbiting planets.
The distinction between minor and major planets is decently clear in our star system, but if we define it poorly it won’t help us understand other systems or why the major ones are important. It’s definitely not enough to disqualify minor planets from being full planets though. Go ahead and declare 8 major planets arbitrarily, but don’t try to justify ignoring the other few dozen planetoids poorly.
Planet is just not a very useful distinction. Like, Mercury, Mars, Ceres and Ganymede have more in common with each other than Jupiter or Neptune.
I think “Planet” should be a gravitationally rounded mass that’s not a star anyway. Those can be divided into rocky and gaseous, and further divided by principal composition.
Smaller than that isn’t usually worth having a name, but moons can be just as interesting as free orbiting planets.
The distinction between minor and major planets is decently clear in our star system, but if we define it poorly it won’t help us understand other systems or why the major ones are important. It’s definitely not enough to disqualify minor planets from being full planets though. Go ahead and declare 8 major planets arbitrarily, but don’t try to justify ignoring the other few dozen planetoids poorly.
That would make Earth-Moon a binary planet. Which I’m cool with, actually.