Neptune does not clear Pluto's orbit.

[jamesqf]

Originally Posted by NeilBlanchard

Planets orbit stars. Moons orbit planets.

There are planets which don't orbit stars. See https://en.wikipedia.org/wiki/Rogue_planet and https://www.universetoday.com/98478/...-solar-system/

Which makes the "cleared the orbit" criterion even more ridiculous :-)

[Angel And The Wolf]

Originally Posted by Xist

So, everybody decided to ditch Pluto twelve years ago, and while everyone had reasons, I just discovered the alleged real reason the other day--Pluto does not clear its own orbit.

I think "Clearing it's own orbit" refers to having it's orbit clear of other bodies. This clearing occurs during the accretion phase of planetary development.
Pluto's orbit is far more eccentric than the other eight planets, and is not in the same general plane as the others. Pluto seems to be a captured body from another solar system, and perhaps too recently for it to clear it's orbit.
I will still call Pluto, a planet in honor of Clyde Tombaugh.

[NeilBlanchard]

Originally Posted by RedDevil

Pluto has 5 moons, so it must be a (dwarf) planet.
https://en.wikipedia.org/wiki/Moons_of_Pluto

Though it is much smaller that the biggest moon in our solar system: Ganymede

Pluto is smaller than our moon.

[NeilBlanchard]

Originally Posted by jamesqf

There are planets which don't orbit stars. See https://en.wikipedia.org/wiki/Rogue_planet and https://www.universetoday.com/98478/...-solar-system/

Which makes the "cleared the orbit" criterion even more ridiculous :-)

Yes - rogue plants are distinct from planets - because they do not orbit.

https://www.youtube.com/watch?v=kKi58i0YD0Y

Some rogue planets probably have life on them.

[gone-ot]

Originally Posted by NeilBlanchard

Yes - rogue plants are distinct from planets - because they do not orbit.

Some rogue planets probably have life on them.

...and, conversely, some planets probably have rogue life on them.

[RedDevil]

Originally Posted by NeilBlanchard

Pluto is smaller than our moon.

Yes. But does that matter?
Ganymede is bigger than Mercury, and Mercury has no moons.
Pluto does have moons; its biggest, Charon, has 1/8 of the mass of Pluto and is the 8th biggest moon in our solar system (not counting Pluto or Mercury in as moons).

And that link to Charon has a nice dig into the subject:

In a draft proposal for the 2006 redefinition of the term, the IAU proposed that a planet be defined as a body that orbits the Sun that is large enough for gravitational forces to render the object (nearly) spherical. Under this proposal, Charon would have been classified as a planet, because the draft explicitly defined a planetary satellite as one in which the barycenter lies within the major body. In the final definition, Pluto was reclassified as a dwarf planet, but the formal definition of a planetary satellite was not decided upon. Charon is not in the list of dwarf planets currently recognized by the IAU.[37] Had the draft proposal been accepted, even the Moon would be classified as a planet in billions of years when the tidal acceleration that is gradually moving the Moon away from Earth takes it far enough away that the center of mass of the system no longer lies within Earth.[38]

If it were me I'd add "... a planet be defined as a body that orbits just the Sun and no other object within the solar system ..." so the moon and Charon remain moons as long as they keep circling around their main planet, never mind the position of their combined center of gravity.

[NeilBlanchard]

Originally Posted by RedDevil

Yes. But does that matter?
Ganymede is bigger than Mercury, and Mercury has no moons.
Pluto does have moons; its biggest, Charon, has 1/8 of the mass of Pluto and is the 8th biggest moon in our solar system (not counting Pluto or Mercury in as moons).

And that link to Charon has a nice dig into the subject:

If it were me I'd add "... a planet be defined as a body that orbits just the Sun and no other object within the solar system ..." so the moon and Charon remain moons as long as they keep circling around their main planet, never mind the position of their combined center of gravity.

There are about 100 other unnamed objects in our solar system - that are LARGER than Pluto. Why aren't they all planets?

[redpoint5]

Seems to me it's because planet isn't well defined.

[jamesqf]

Originally Posted by NeilBlanchard

There are about 100 other unnamed objects in our solar system - that are LARGER than Pluto. Why aren't they all planets?

Because we don't know enough about them? Certainly some of the larger KBOs should be considered planets.

[NeilBlanchard]

I think we "care" about Pluto because it was discovered a while ago.

Originally Posted by redpoint5

Seems to me it's because planet isn't well defined.

There is a good definition, and it is clearer now.