Pluto is was and always will be a planet

[Roboramma]

Definitions are never about limiting the number of members in a category. They are about clarifying distinctions between members. There really is a difference between Mammals and Birds, both form separate clades, and that's the reason for those separate categories.

These categories should about identifying meaningful patterns in nature. The difference between a planet and a star is an important such distinction. Contrary to what I said in my last post the difference between planets and moons is also a meaningful distinction in understanding the dynamics of the solar system.

Finding a category that helps to give us insight into nature seems like a reasonable way to go about defining categories.

 

[Belz...]

Definitions are never about limiting the number of members in a category. They are about clarifying distinctions between members.

And yet they changed the definition of 'planet' to limit the number of members in the category.

 

[Ziggurat]

Another thing: Do we want kids to learn the planets?

Yes, because if you throw general topics at them early on, not only will that equip them with all sorts of knowledge that may come in handy, and allow them to understand things from at least a basic perspective, but it also will open doors to them, and potentially interest them in a future career.

Sure. But do they need to know all the planets for that purpose? I don't see that they do. I think suffices to teach them some subset of "important" planets, and then let them know there are some more smaller ones out there.

No but you exclude streams from the rivers category, don't you?

Depends on who's doing the defining. For example, the United States Board on Geographic Names defines rivers as a subset of stream, which is basically any linear flowing body of water and thus includes rivers, creeks, brooks, etc.

 

[Belz...]

Sure. But do they need to know all the planets for that purpose? I don't see that they do. I think suffices to teach them some subset of "important" planets, and then let them know there are some more smaller ones out there.

Sure. How do we determine which ones, and do they deserve a separate category, while we're at it?

Depends on who's doing the defining. For example, the United States Board on Geographic Names defines rivers as a subset of stream, which is basically any linear flowing body of water and thus includes rivers, creeks, brooks, etc.

Yes but the point is that not all streams are rivers. And in some languages you have additional categories.

 

[jeremyp]

Did you know that not drawing pants on Pluto was okay because he did not speak and was presented as a dog/pet, whereas drawing pants on Goofy was considered crucial for decorum because he speaks in the cartoons and therefore was human-enough to need clothes. Presumably Goofy's ancestors ate of the fruit of knowledge in Eden; Pluto's did not.

Donald Duck could speak but did not wear either pants or trousers.

 

[Elagabalus]

When the IAU says Pluto ain't a planet you say how high!

 

[azzthom]

Donald Duck could speak but did not wear either pants or trousers.

But did wear a towel when he got out of the shower.

 

[Belz...]

When the IAU says Pluto ain't a planet you say how high!

No, you say "how many astronomical units?"

 

[theprestige]

Sure, that works. I just think there's something more elegant about the idea that anything like the earth would be a planet, no matter where it ends up.

"Like the earth" of course doesn't mean identical to the earth, and we can go back and forth about how different from the earth something can be without wanting to have a different category.

Maybe "like the earth" shouldn't even be the criterion. That's just what I found when I thought about what a planet is to me and why I would want one thing or another included in that definition. Someone could present an argument for a better way of thinking about what planets are and I might be swayed by it.

If the earth's orbit was perturbed to the point where it was expelled from the solar system I think I'd still consider it a planet, and similarly if it somehow ended up orbiting Jupiter.

For sure. I don't know if I've already said it in this thread, but for the past couple days I've been thinking it: "Planet" is really more of a literary term than a scientific one. Which is why reclassifying Pluto is referred to as a "demotion", and why the Tyson/IAU push to reclassify it has more of a Showboaty McShowboatface feel to it than a "good science done well" feel to it.

 

[theprestige]

Ok, call it a reasonable thing to do, since knowing about the universe is part of teaching children about the world around us. The result is the same: sounds like a good idea to me.

Calling it reasonable doesn't make it reasonable. I'll call it the reasonable thing to do if there's a convincing argument from reason to support it.

In general, we don't create definitions for the purpose of reducing the number of things schoolchildren have to deal with. Maybe you think that stars are an important part of the universe that children should be taught. Are you suggesting we should maybe redefine "star" to mean "O-class stars on the Hertzprung-Russel" diagram? Those are the least common class of stars, so it would ease the burden on schoolteachers for sure.

Yes, because if you throw general topics at them early on, not only will that equip them with all sorts of knowledge that may come in handy, and allow them to understand things from at least a basic perspective, but it also will open doors to them, and potentially interest them in a future career.

Stipulated.

What is wrong with this as a general concept?

Planets are spherical under their own gravity, and orbit stars. Asteroids orbit stars, but don't have the mass to form into spheres. Moons may or may not be spherical, and orbit planets. There are a few planets in our solar system that you can see with the naked eye, and many more besides. Here's a few notable planets to get you started. If you decide to pursue the subject, you'll find there's some edge cases, which are probably the most interesting part.​

No but you exclude streams from the rivers category, don't you?

I can't say that I've ever been so committed to enumerating rivers to children that I've had to exclude streams just to make the numbers more manageable. I think you're making Introductory Natural Science waaay more complicated than it needs to be.

I don't understand your objection. I was responding to ceptimus' post about keeping the original definition of planet. If we keep it, then it would apply to what we know now of our solar system. Otherwise we have to alter the definition to excluse the other "wanderers" we've discovered and we're right back to square one.

Noted. Fair enough.

I think so. All professions have categories of this or that so you can classify them to simplify language and operations. Why do you think it would be different here?

You think so, but what has Tyson/IAU actually said about it?

 

[aleCcowaN]

When the IAU says Pluto ain't a planet you say how high!

No, you say "how many astronomical units?"

Leave it in "how many nanoseconds light?"

 

[dudalb]

I prefer the Daly Show solution to the "Is Pluto A Planet" question.
Would Galactus have it for Lunch?

 

[Roboramma]

And yet they changed the definition of 'planet' to limit the number of members in the category.

And if that's the reason for the redefinition, I think it's a bad reason.

If on the other hand someone said: "Damn, this definition includes many bodies that really don't seem to fit what we meant by planet when we originally came up with it, let's try to look more closely at what that category is trying to define and make a more rigorous definition." that would make sense.

Since that doesn't seem to be what happened, I think what you say above is a good case for why the new definition isn't particularly good. It's not based on some important distinction in the world.

 

[theprestige]

I prefer the Daly Show solution to the "Is Pluto A Planet" question.
Would Galactus have it for Lunch?

The Daily Show is an ally of Big Science and Neil Degrasse Tyson. They're pandering to comic book nerds because reasons. Boop to that.

 

[arthwollipot]

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.

Why? What is it about the label "planet" that makes it inherently more valuable to you?

 

[Ziggurat]

Why? What is it about the label "planet" that makes it inherently more valuable to you?

Does it matter? That part was just a statement of personal opinion. It's not actually part of my argument for changing the definition.

 

[arthwollipot]

Does it matter? That part was just a statement of personal opinion. It's not actually part of my argument for changing the definition.

I think it does matter. You appear to be putting stock in the label "planet" that the label "dwarf planet" does not have. You appear to be implying that it is better to have the "planet" label than to have the "dwarf planet" label.

If that is not the case, and your argument is about nothing but process, then I apologise and withdraw my question.

 

[Darat]

Irrelevant. We're talking about how the word is defined. If we're to keep the definition, we have to apply it to the objects we know of now.

No we don't. The easiest way to get everyone alongside with a new definition would be to say "historically we have 9 bodies that we call planets, for any future body to be considered a planet it needs to meet the following criteria...." Then purists could say under their breaths "drawf planet" when anyone calls Pluto a planet and Plutophiles can under their breaths say "yes a planet" when Pluto is described as a drawf planet.

 

[Belz...]

Calling it reasonable doesn't make it reasonable.

Now you're moving the goalposts. You objected that my wording was inadequate, now you're ignoring that and switching to a different line. It almost seems like you want to find a reason to disagree.

In general, we don't create definitions for the purpose of reducing the number of things schoolchildren have to deal with.

Who cares what the general case is? Read up on why they changed the definition.

What is wrong with this as a general concept?

I've already explained why several times, prestige. It would result in a great number of planets, possibly hundreds or thousands, depending on how many we eventually fine, and the IAU wanted to avoid that.

I can't say that I've ever been so committed to enumerating rivers to children that I've had to exclude streams just to make the numbers more manageable. I think you're making Introductory Natural Science waaay more complicated than it needs to be.

No, I'm using a parallel to illustrate the point but somehow you missed it.

Noted. Fair enough.

You think so, but what has Tyson/IAU actually said about it?

Do you acknowledge and agree with my argument there?

 

[Belz...]

And if that's the reason for the redefinition, I think it's a bad reason.

Sounds like as good a reason as anything. Definitions are arbitrary and can reflect a great number of purposes or incentives.

If on the other hand someone said: "Damn, this definition includes many bodies that really don't seem to fit what we meant by planet when we originally came up with it, let's try to look more closely at what that category is trying to define and make a more rigorous definition." that would make sense.

I've also argued that it is also the case that trans-neptunian bodies are different in many respects to the canonical eight.

Since that doesn't seem to be what happened, I think what you say above is a good case for why the new definition isn't particularly good.

That sounds a bit circular. You've defined 'good' as excluding that reason, and then used that to call it bad.