"How I Killed Pluto and Why It Had It Coming" - awesome title for an Astronomy book

Bring back Pluto!

It's been renamed to Planet America, thank you for your attention on this matter.

> “One of the biggest flaws with the IAU definition is that you can have the same object in two different orbits,” says Kornfeld. “In one, it’s considered a planet, and in the other, it’s not considered a planet.”

So… planet Ganymede when? Or Titan?

It seems as though Pluto's primary problem is "clearing the neighbourhood." Given Pluto's orbit travels closer and further from the sun than Neptune, does Neptune also have the neighborhood clearing problem since it has not cleared Pluto?

  In celestial mechanics, "clearing the neighbourhood" (or dynamical dominance) 
  around a celestial body's orbit describes the body becoming gravitationally 
  dominant such that there are no other bodies of comparable size other than 
  its natural satellites or those otherwise under its gravitational influence.[0]
  

https://en.wikipedia.org/wiki/Clearing_the_neighbourhood

I'm in the same camp. I believe the classification of Pluto as a dwarf planet was arbitrary and inconsistent. I mean, it's been known as a planet for almost 80 years and suddenly we demote it?

I believe someone was trying to make a name for themselves here and ignoring the history of Pluto and its discovery.

Back in school I learned the acronym:

My Very Easy Method Just Speeds Up Naming Planets

And it was so convenient! Does anyone know a good alternate now that the P is gone?

I can solve this! What is incompatible with being both a dwarf planet and a major planet? Peter Dinklage is both a dwarf actor and a major actor. Just acknowledge that Pluto is both too. You're welcome.

> “One of the biggest flaws with the IAU definition is that you can have the same object in two different orbits,” says Kornfeld. “In one, it’s considered a planet, and in the other, it’s not considered a planet.”

No, there is no flaw in this, and moreover there is nothing new in this. This is how it has always been, it is not something invented recently.

In the Solar System, there are 3 Mercury-sized satellites and other 3 Moon-sized satellites, besides the Moon. If they had not been in their orbits as satellites, they might have very well been planets. Therefore the old definition of "planet" also depended on the orbit of the body, not only on the size and shape of the body.

Most of those satellites are bigger than Pluto. Triton, the biggest satellite of Neptune, had been in the distant past another planet with an orbit close to Pluto, but it was captured by Neptune and it has become a satellite. Otherwise it would have remained a "dwarf planet", orbiting close to Pluto.

The current definition of "planets" and "dwarf planets" is fine.

If anything, there are too few planet classes, not too many. A more useful classification is into big planets, medium planets and small or dwarf planets, where the Solar system has 4 big planets, 4 medium planets, and a lot of small planets.

The big planets, i.e. which are big enough to retain the volatile chemical elements, like hydrogen and noble gases, not only the refractory elements, have a very different chemical composition from the medium planets, and this difference will also exist in any other stellar system that has condensed from gases like those at the origin of the Solar System, with more oxygen than carbon (there exists the possibility of stellar systems with a different chemical composition than the Solar System, formed by condensing from gas mixtures with more carbon than oxygen).

You know, this is really just a fantastic opportunity to realize the phenomenal psychological power of "headcanon". Who cares if Pluto is or is not tagged with the word "planet" by some organization you know effectively nothing about, have no control over, has no control over you, and couldn't so much as move a pebble on the planetary body in question any time in the next 20 years, if not more?

Have whatever emotional relationship you like with "Pluto" and don't wait around for others to validate it. It's fine. Nobody can stop you. I'm a bit fond of Ceres myself. Nobody can stop me. Nobody needs to approve it. Take control. Write your own headcanon.

In case anyone was curious, the Moon is bigger than Pluto. Pluto's 2/3 the size of the Moon. If any dwarf planet should be upgraded to a planet, it's Eris. Eris's diameter is over 600km bigger than Pluto's.

The main objection to calling Pluto a planet appears to be that if Pluto is a planet then up to about 200 other objects should also be called planets, that the list would be of unknown size and regularly changing.

That's an objection? No, that's a benefit! I think it'd be awesome to be regularly discovering new planets.

This seems like the least important issue in the world to keep complaining about.

The actual problem here is weirdly aggressive nerds who are incapable of nuance, and insist that an astronomical classification (Pluto is not a planet by the IAU definition) should be used in non-astronomical contexts.

Historically and culturally, Pluto is considered a planet. An IAU classification shouldn't be used to try and retroactively change that, because the IAU does not have control over history and culture. It's a fun fact (did you know that Pluto is not classified as a planet by astronomers?) not a diktat.

Similarly, a banana is 'officially' a berry, which means that it is classified as a berry by botanists. This does not mean it is considered a berry in any other contexts. If you told someone you had made a berry crumble and it was filled with bananas, you would look strange. We have countless examples of this (often focused around food): a tomato does not belong in a fruit salad no matter what botanists say.

Different terms are used with different specificity in different settings. Language and culture and [older disciplines] are not governed by the rules of [newer disciplines or bodies]. If people with 'I love space' t-shirts would stop "um actually"-ing, no one would have a problem.

[delayed]