Belz...
Fiend God
Belz...
Fiend God
Again, I'd ask what you base your "should" upon.
Good. Do we agree that a planet that loses its planet...ary qualities is no longer a planet, regardless of what those qualities are?
Because I'm still trying to grasp what your alternative is, and why it's more useful. So far, as I noted, mostly your reasoning is that it "feels" right to you. I don't find that very convincing.
Ok why do we classify genera and species and orders at all, then? It's because there's a crapton of lifeforms and we want to be able to classify them for various purposes. It's the same with solar system bodies.
It no more matters than yours, actually. I didn't claim otherwise.
No, they all orbit the sun and have hydrostatic equilibrium.
Ziggurat
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I just told you in the very part you quoted: because it's misleading. Really, Belz, do pay attention.
You forgot that I already suggested using a mass or diameter threshold if you want to eliminate smaller objects.
Belz...
Fiend God
I read it. Your jab about Jupiter is irrelevant to the larger point, and 'misleading' is meaningless in this context, since we're discussing defining the term 'planet' in the first place. I'm asking you why you're putting "should" in your arguments over and over. You're not going go make your case if you keep phrasing your arguments in moral language. How do you determine what "should" or "shouldn't" be used? We're talking about planets, not gay marriage.
I didn't. Stop trying to make it about me. What mass would you suggest, and why? How would that be useful in any way?
Ziggurat
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It's completely relevant to whether or not the IAU definition is a good definition to use.
It's completely meaningful. A definition of the word which leads to misleading usage is inferior to a definition of the word which does not lead to misleading usage.
"Should" implies a value assignment, but that doesn't require that the value is a moral one. And a value assignment is necessary here. If there is no value assignment, there can be no preference, and everything is arbitrary. The entire premise of even discussing what definition to use is that we can assign some value to different definitions to compare them.
I thought your complaint was just that my explanation for the value assignment wasn't clear to you, but if you're objecting to having a value assignment at all, then there's really no point in even having a discussion.
You were the one who claimed it would be useful to eliminate those smaller, less relevant objects from the definition of planet, not me. And a threshold for mass or diameter is better than clearing the neighborhood to achieve that goal because it's less ambiguous, easier to evaluate, and doesn't produce misleading usage.
Belz...
Fiend God
Only if I accept your value judgment, which you have to admit is not something you can establish convincingly.
Except how is it misleading?
It's a definition. Of course it's arbitrary. I just don't think you've established why anything "should" be this way or not.
Well, let me clarify: I don't think the value judgment in and of itself is undesirable. But if you want to convince people that your judgment is correct, you'll have to do more than just state it.
So what mass would you choose?
The 'clearing its orbit' thing is pretty nonsensical, IMO. The Trojans share Jupiter's orbit precisely because Jupiter is very massive and able to herd asteroids into its Lagrange points. Earth also has a trojan at its L4 point and several other bodies locked into a 1:1 resonance orbit, including Cruithne.
The other definitions seem fine to me - enough gravity to pull itself into approximately spheroid shape and in orbit around the sun (star, stars) rather than another planet.
Other star systems may have twin planets orbiting each other, where their sizes are so similar that it makes no sense to name one of them as a planet and the other as a moon - but that does not apply in the solar system to any planets/moons/dwarf planets so far discovered.
You could introduce other arbitrary definitions, such as "visible to the naked human eye." That might include Uranus, even though the ancients never noticed it, but would exclude Neptune, Pluto and other dwarf planets.
As someone said already, whenever you attempt to classify things, there are always likely to be edge conditions. Introducing ill-defined criteria such as 'sweeping clean their orbits' just leads to confusion and argument.
If you want to exclude Pluto, just set a minimum mass to qualify as a planet - that would mean you could then leave out the 'pulling itself into a sphere' requirement as any potential planets bigger than Pluto but smaller than Mercury would do that anyway.
The other definitions seem fine to me - enough gravity to pull itself into approximately spheroid shape and in orbit around the sun (star, stars) rather than another planet.
Other star systems may have twin planets orbiting each other, where their sizes are so similar that it makes no sense to name one of them as a planet and the other as a moon - but that does not apply in the solar system to any planets/moons/dwarf planets so far discovered.
You could introduce other arbitrary definitions, such as "visible to the naked human eye." That might include Uranus, even though the ancients never noticed it, but would exclude Neptune, Pluto and other dwarf planets.
As someone said already, whenever you attempt to classify things, there are always likely to be edge conditions. Introducing ill-defined criteria such as 'sweeping clean their orbits' just leads to confusion and argument.
If you want to exclude Pluto, just set a minimum mass to qualify as a planet - that would mean you could then leave out the 'pulling itself into a sphere' requirement as any potential planets bigger than Pluto but smaller than Mercury would do that anyway.
PhantomWolf
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Neptune called and said to stick your suggestion up Uranus!
PhantomWolf
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you forgot 1 Tesla Volt.....
Ziggurat
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I don't think most people need a lot of convincing that things like clarity are good values to have in language.
You're the one who wants to filter out smaller objects, not me. I'm just suggesting a better way to do it than clearing the neighborhood. Pick whatever mass threshold filters out a number you find optimal. I'm perfectly content to not bother at all.
Dr.Sid
Philosopher
So is your problem with the definition, or the fact, that Pluto specifically is not a planet anymore ?
Ziggurat
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Primarily the definition, which I think is a clumsy kludge to exclude Pluto for arbitrary reasons while trying to mask that its exclusion is arbitrary. If you're going to exclude Pluto arbitrarily, at least make the dividing line clean, like mass or diameter.
I admit that I would like a definition that includes Pluto as well, but I've actually got more love for Haumea than Pluto. Haumea is really cool, and I'd like to see it as full fledged planet.
Belz...
Fiend God
You're the one making the CLAIM that it would be clearer and less misleading and all that. I'm asking you to make a case for it. Otherwise this discussion is simply you having an opinion you can't support and me having an opinion, and everybody has an opinion but no argument.
Yes but you proposed mass before that point, hence my question.
Belz...
Fiend God
The original idea was to manage the growing number of trans-neptunian bodies that were being discovered. I don't think they set out to exclude Pluto specifically, but I could be wrong.
angrysoba
Philosophile
Now this sounds as though you are attributing dark motives to those who excluded Pluto, but I think the argument does not stand up.
I recently heard a podcast between Sean Carroll and Michael Brown. The latter wrote a book called How I Killed Pluto and Why It Had It Coming. On the podcast, and presumably in greater length in the book, Michael Brown explained that he had been one of the people most responsible for arguing against planethood for Pluto, but also that he would have had most to gain from including Pluto, and indeed Haumea, and Eris, and Makemake given that he had discovered them!
Ziggurat
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I already did. At some point, repetition becomes pointless.
Ziggurat
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No, I don't mean dark motives. I mean I think they decided to exclude Pluto, for reasons which don't really matter to me here, and then found a definition which would do that, rather than develop a definition and then see if Pluto would fit it.
Ziggurat
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I'm not claiming they only wanted to exclude Pluto, but I think they did want to exclude it, because of its similarity to the other trans-Neptunians.
And why does calling them dwarf planets instead of planets make them easier to manage? I don't see that it does.
Belz...
Fiend God
Where did you explain why it's meaningless? Once you repeated that you said it, and now you say you've explained it.
But yes, repetition becomes pointless, so how about you break from that and make an actual argument for your suggestions? I honestly don't think it'd be hard for you to do. You just have to move beyond how things "feel".
Belz...
Fiend God