So Pluto is a planet!?

[YNM]

I think that the reason why does the small, inner "large" bodies are planets (including Earth), aren't just because of their physical properties - it's also accounting for other things, like orbital parameters and relative size within the neighborhood. For example, mercury is small and the orbit is fairly eccentric, but then it's neighborhood is devoid of small bodies (due to tidal forces of Sun, radiation pressure, maybe other things). Earth and Venus goes the same, Mars seems to have nearly no neighbors. Pluto, instead, have fairly many similar bodies in similar orbits - hence why there would be too many if Pluto has to be a planet. The same went for Ceres.

My own opinion (and interpretation), but maybe we should start to draw the borderline. Does the mass of stable scattered things (ie. asteroids, comets, etc.) becomes larger the farther they are from the Sun ? Are there any average trends ? Could this mass used for differing between planets and not planet ? Maybe tisserand values, or eccentricity limit ? Or some combination ?

[Las-pen]

Why does everyone care about Pluto not being a planet anymore, it's not like it stopped existing when it was classified as a dwarf-planet.

What about all the other dwarf planets?

Ceres is a dwarf-planet, and it's closer to home.

Shouldn't it have a huge "It's a planet" following?

Well it doesn't, because "no one" knows about it, and if they did they wouldn't care.

It's like the people who think that our Sun is called Sol, it might be in some languages, but it's just the Sun in English.

You took the words right out of my mouth. There are bigger objects in Solar system than Pluto, like Eris, that are not classified as planets. If you grew up with something and you don't like changes doesn't make it right.

And technically Pluto is a Double Dwarf Planet, since Common Mass Centre for Pluto and Charon lies outside of Pluto

[Las-pen]

I think Pluto should be a planet. If it was one it always will be one to me. Not just as a science thing, but it's also kind of personal. My dad actually met and shook hands with Clyde William Tombaugh (the guy who discovered Pluto). But all personal matters aside, Pluto should be a planet.

By that logic Ceres should be planet, because it once was. Then they discovered other bodies with same orbit. Same thing happened with Pluto.

[ANWRocketMan]

I would suggest a system where you speific bodies that identifies between size, shape and composition. In the sense of asteroid, comet, planet, gas giant. But hen have an additional class sytem that describes what siuation this body finds itself in. As in a class 1(circular orbit, cleared path), class(elliptical orbit etc.), class 3(moon of another body). Etc.

[KerikBalm]

And technically Pluto is a Double Dwarf Planet, since Common Mass Centre for Pluto and Charon lies outside of Pluto

Did they formally adopt a definition for a double planet? or is that just a "colloquail" definition.

The problem I see with that definition, is that Earth is not a double planet, but will become a double planet when the moon moves farther out.

[magnemoe]

By that logic Ceres should be planet, because it once was. Then they discovered other bodies with same orbit. Same thing happened with Pluto.

Was this the main reason, or that they discovered lots of asteroids and had to put an lower limit.

Much the same with Pluto, they finds lots of cupier belt objects and would be lots of planets after some time,

[Acemcbean]

No, Pluto is not a planet for several reasons. Pluto is, first of all, not the largest object in its orbital path, which means its orbit isnt stable, one of the defining factors of a planet. Secondly, if we are to consider Pluto a planet, we would first have to make both Eris and Ceres planets, as they are both either larger or almost equal to size to Pluto, and actually have mostly clear orbits. Finally, Pluto only barely even makes it past being called a Planetoid: an object in space which is not quite an asteroid, but not quite a planet.

[Acemcbean]

Also, the whole mumbo-jumbo from Harvard about it being a "cultural" thing is, well, just kind of stupid. Im trying to be nice because, ya know, its HARVARD. But seriously, why in the world is a law school getting involved in space?

[Camacha]

Secondly, if we are to consider Pluto a planet, we would first have to make both Eris and Ceres planets, as they are both either larger or almost equal to size to Pluto, and actually have mostly clear orbits.

Indeed, we do. The rest is just repeating the things discussed before, not much use mulling over them again and again.

[Frannington]

Pluto can be whatever it wants to be and y'all need to stop laying a trip on it.

[KerikBalm]

Well, I know for a fact that pluto doesn't want to be a planet, so case closed?

[TheFlyingPigs]

You gotta BELIEVE...

[Bill Phil]

Why not make "Planet" a broad term? Then divide planets into "Major", "Minor", etc.

That way everybody wins. People who say Pluto is a dwarf/minor planet, and people who say that Pluto is a planet.

[fenderzilla]

The scientific community agreed that they don't yet have a proper definition of what a planet is. Pluto is a planet again because, in light of this, they decided its demotion was premature. I assure you that once a proper definition has been made, Pluto will not fit it.

BTW if Pluto is a planet then by all means its twin Charon is, too.

[Rondon]

Why not make "Planet" a broad term? Then divide planets into "Major", "Minor", etc.

That way everybody wins. People who say Pluto is a dwarf/minor planet, and people who say that Pluto is a planet.

Ah but we already have that. And it's even simpler than that, there's either planet or dwarf planet.

[KerikBalm]

The scientific community agreed that they don't yet have a proper definition of what a planet is. Pluto is a planet again because, in light of this, they decided its demotion was premature.

Citation please

[Bill Phil]

Ah but we already have that. And it's even simpler than that, there's either planet or dwarf planet.

What I said was a way to end the argument, because then it's both.

[kStrout]

Eris is only 20km(radius) smaller than Pluto, If Pluto is to be considered a planet than Eris really should be as well.

[Rondon]

What I said was a way to end the argument, because then it's both.

Okay, the first thing I can think of is how much additional trouble it would be to constantly say major planet.

[Bill Phil]

Okay, the first thing I can think of is how much additional trouble it would be to constantly say major planet.

Uh...

How would that be a big problem? "Major planet" would be more specific, like terrestrial planets or gas planets. You could still call it a planet.

[Camacha]

Ah but we already have that. And it's even simpler than that, there's either planet or dwarf planet.

It seems like we do, but in reality we don't. For some quirky reason, dwarf planets are not a subcategory of planets - it just happens to sound a lot alike. I would not mind that system at all, making anything round a planet and dividing that into subcategories to make life a little easier with all the newly discovered objects.

[Holo]

Eris is only 20km(radius) smaller than Pluto, If Pluto is to be considered a planet than Eris really should be as well.

I'd accept that if Pluto became a planet again, as long as Ceres, Haumea and Makemake became planets as well.

[KerikBalm]

and Eris, and Sedna, and what about quoarar?

What about the potentially dozens of other sedna like bodies out there?

[Camacha]

and Eris, and Sedna, and what about quoarar?

What about the potentially dozens of other sedna like bodies out there?

This thread should die already, the same questions pop up over and over again. Read back and see for yourself!

[metaphor]

Why not make "Planet" a broad term? Then divide planets into "Major", "Minor", etc.

That way everybody wins. People who say Pluto is a dwarf/minor planet, and people who say that Pluto is a planet.

But this is a scientific definition. The point is not to please the most people. The point is to make a consistent categorization of natural bodies.