Pluto is a Giant Comet

Dan_D said:
Here is the reason for the disagreement taken from Wikipedia:

"Stern, currently leading NASA's New Horizons mission, disagrees with the reclassification of Pluto on the basis of its inability to clear a neighbourhood. One of his arguments is that the IAU's wording is vague, and that—like Pluto—Earth, Mars, Jupiter and Neptune have not cleared their orbital neighbourhoods either. Earth co-orbits with 10,000 near-Earth asteroids (NEAs), and Jupiter has 100,000 trojans in its orbital path. "If Neptune had cleared its zone, Pluto wouldn't be there", he has said."

By that reasoning we are living on a Dwarf Planet and Jupiter would need to be reclassified as well. That simply doesn't make sense. There is nothing gained by the reclassification. Nothing is really implied by the term dwarf planet other than the planets' size. If the IAU had decided that a planet had to be round, in direct orbit of the sun, and exceed a certain size threshold, I think that would be fine.
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From Wiki:
Clearing the neighbourhood around its orbit" is a criterion for a celestial body to be considered a planet in the Solar System. This was one of the three criteria adopted by the International Astronomical Union (IAU) in its 2006 definition of planet. In 2015, a proposal was made to use the criterion in extending the definition to exoplanets.

In the end stages of planet formation, a planet (as so defined) will have "cleared the neighbourhood" of its own orbital zone, meaning it has become gravitationally dominant, and there are no other bodies of comparable size other than its natural satellites or those otherwise under its gravitational influence. A large body that meets the other criteria for a planet but has not cleared its neighbourhood is classified as a dwarf planet. This includes Pluto, which is constrained in its orbit by the gravity of Neptune and shares its orbital neighbourhood with Kuiper belt objects. The IAU's definition does not attach specific numbers or equations to this term, but all the planets have cleared their neighbourhoods to a much greater extent (by orders of magnitude) than any dwarf planet, or any candidate for dwarf planet.
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Yes, there's still a *relatively* tiny bit of debris flying around the solar system crossing major planetary orbits, but the sizes and orbits of the major planets have completed their evolution and are now in a stable long-term state.

Pluto's mass is tiny compared to Neptune, and it's locked in a resonance with it anyway. Same with the Trojan asteroids and Jupiter. They can't collide, so their orbits are considered 'clear.'
 
DeathFromBelow said:
From Wiki:


Yes, there's still a *relatively* tiny bit of debris flying around the solar system crossing major planetary orbits, but the sizes and orbits of the major planets have completed their evolution and are now in a stable long-term state.

Pluto's mass is tiny compared to Neptune, and it's locked in a resonance with it anyway. Same with the Trojan asteroids and Jupiter. They can't collide, so their orbits are considered 'clear.'
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Funny I seem to recall several somethings hitting jupiter a few years back...
 
kju1 said:
Funny I seem to recall several somethings hitting jupiter a few years back...
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Yes, comet Shoemaker. Do you have a point?

The sizes and orbits of the major planets are in a stable long-term state. Dwarf planets still have substantial mass in their orbital neighborhood.
 
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I think we need a "Pluto is ...." thread. Sort of like the "Happiness is..." from Peanuts.

For example:

Pluto is the neighbor of Planet 10.
 
DeathFromBelow said:
From Wiki:


Yes, there's still a *relatively* tiny bit of debris flying around the solar system crossing major planetary orbits, but the sizes and orbits of the major planets have completed their evolution and are now in a stable long-term state.

Pluto's mass is tiny compared to Neptune, and it's locked in a resonance with it anyway. Same with the Trojan asteroids and Jupiter. They can't collide, so their orbits are considered 'clear.'
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Let me approach this another way. Let's say a Mars sized planet were ejected from another solar system and was headed for Jupiter. Would you not consider that rogue planet a planet? Jupiter's path wouldn't be clear anymore so is it all of the sudden not a planet? Or how about this: If a Toyota accelerates out of control and is on a collision course with another car, are both of those objects no longer cars? Is a car only a car when it's on the road? I think the idea that a given planet's orbit and neighborhood having anything to do with it's classification is ridiculous. How an object is moving or what's around it really shouldn't have any bearing on whether we call it a planet or not. Size or mass classification in addition to being round seems more reasonable to me. I don't think we need anything more than that to classify whether something is or isn't a planet.
 
viper1152012 said:
Accretion will prove me right in the long run.
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actually, probably NOT.
Odds are Pluto will either be expelled from Solar system or assume its role as Neptune satellite.
My money is on the later.
Composition-wise it is indeed quite similar to a comet.
 
Dan_D said:
Let me approach this another way. Let's say a Mars sized planet were ejected from another solar system and was headed for Jupiter. Would you not consider that rogue planet a planet? Jupiter's path wouldn't be clear anymore so is it all of the sudden not a planet? Or how about this: If a Toyota accelerates out of control and is on a collision course with another car, are both of those objects no longer cars? Is a car only a car when it's on the road? I think the idea that a given planet's orbit and neighborhood having anything to do with it's classification is ridiculous. How an object is moving or what's around it really shouldn't have any bearing on whether we call it a planet or not. Size or mass classification in addition to being round seems more reasonable to me. I don't think we need anything more than that to classify whether something is or isn't a planet.
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A 'rogue planet' is what it is: an object that was formerly a planet or dwarf planet that has been ejected from a star.

I get what you're saying, really I do, but the definition refers to the 'orbital neighborhood,' and it only makes sense in a stable system of planets. Once you start bringing in massive objects like rogue planets or other stars passing by you're talking about things that could potentially change the long term configuration of the entire solar system. There's not much point in defining what the various bits 'are' until they actually reach a stable configuration. If you happen to be around while the solar system gets torn apart feel free to call the planets whatever you want!

I think their definition clear enough: once a solar system is established and the various major objects are formed you can define them as planets or dwarf planets depending on their mass relative to the rest of the crap in the same orbit.

geok1ng said:
actually, probably NOT.
Odds are Pluto will either be expelled from Solar system or assume its role as Neptune satellite.
My money is on the later.
Composition-wise it is indeed quite similar to a comet.
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Pluto is locked in a 2:3 resonance with Neptune. They are in a stable configuration and can't intercept eachother unless something from outside the solar system changes their orbits.
 
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kju1 said:
Oh please, we arent talking about "laws" of physics or chemical interactions here. We are talking about a man made arbitrary definition of a celestial body. There certainly can be exceptions made to the standard. The universe wont implode if we call Pluto a planet.
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Then you would have the same definition applying differently based on people's feelings. When you bring feelings into science it's no longer science; therefore it does not belong.
 
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Mind as well make pluto into a deathstar so people give it the love it deserves. If you can't be a planet, become a battle station?
 
RussianJ said:
Mind as well make pluto into a deathstar so people give it the love it deserves. If you can't be a planet, become a battle station?
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nopluto-battlestation.jpg
 
kju1 said:
Oh please, we arent talking about "laws" of physics or chemical interactions here. We are talking about a man made arbitrary definition of a celestial body. There certainly can be exceptions made to the standard. The universe wont implode if we call Pluto a planet.
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But apparently people implode if we don't call Pluto a planet... case in point, this thread.
 
Dan_D said:
Not necessarily. We could have established other criteria to "sort" these objects if need be.
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We did, and Pluto also happened to match those criteria as well.

Hey stop being so sad about the lack of Pluto being a planet, it's better than a planet now since it has a classification named after it, the Plutino.
 
From what I can tell, the only reason they downgraded pluto to a non-planet is because they didn't have the guts to say all these others larger than it were planets too.
 
Pluto is a planet.....
R) No it isn't a planet
Ok, Pluto is a dwarf planet then
R) No it isnt,'t a dwarf planet
Ok, Pluto is a giant comet then !!
R) No it isn't a giant comet, its planet X !!
WFT, I give up !!!
 
Catergory theory suggests it's a celestial object, class planet, subclass dwarf-planet. Too many new-agey asshats on payroll, not enough mathematicians.
 
Zumino Zufeilon said:
So, you're cool with the Moon being a planet then?

By both Mass and Volume the Moon is a good deal larger than Pluto. The Moon does not "exactly" orbit the Earth, rather they both orbit a point that is just inside the Earth (meaning the pair orbit a Point that is not actually near the center of the earth)

That was one of the discussions that lead to "dwarf planet" category, as a way to encapsulate all the "grey-ness" in a single bucket.
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Except the Earths moon doesnt rotate around the sun o_Oo_Oo_O
 
Dan_D said:
Name one object in the belt larger than Pluto. Eris was originally thought to be larger, but was determined to be slightly smaller when the probe actually made it out that far. It's believed that Eris has greater mass than Pluto, but it isn't larger. Even by the old estimates of Eris's size, it was the one thing larger than Pluto out there we know of. All the other "Dwarf Planets" that we know of are smaller than Pluto. Some of them do come relatively close to Pluto's size but nothing out there is larger than Pluto as far as we know today. I would agree that this could change and we have determined there is a lot of potential objects out there.

What difference does it make if we are a 9 planet system or a 38 planet system? I don't mind having set criteria for planets which changes the status of some of these objects but the reason chosen in this case is stupid. Here is the reason for the disagreement taken from Wikipedia:

"Stern, currently leading NASA's New Horizons mission, disagrees with the reclassification of Pluto on the basis of its inability to clear a neighbourhood. One of his arguments is that the IAU's wording is vague, and that—like Pluto—Earth, Mars, Jupiter and Neptune have not cleared their orbital neighbourhoods either. Earth co-orbits with 10,000 near-Earth asteroids (NEAs), and Jupiter has 100,000 trojans in its orbital path. "If Neptune had cleared its zone, Pluto wouldn't be there", he has said."

By that reasoning we are living on a Dwarf Planet and Jupiter would need to be reclassified as well. That simply doesn't make sense. There is nothing gained by the reclassification. Nothing is really implied by the term dwarf planet other than the planets' size. If the IAU had decided that a planet had to be round, in direct orbit of the sun, and exceed a certain size threshold, I think that would be fine.
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Ceres......
 
Over my life time I have seen a lot of people try to reclassify or rename things after learning new information or sometimes its just because they want to rebrand it. It usually met with insane resistance, especially if people have the childhood nostalgia going on.

What is interesting is that scientist can fall prey to this too. If scientists were really objective they wouldn't let those things influence their arguments and Pluto wouldn't be a planet period, there wouldn't have even been a debate once the evidence was solidified. Not a dwarf planet either.
 
86 5.0L said:
Except the Earths moon doesnt rotate around the sun o_Oo_Oo_O
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Well, technically they both revolve around the Sun. ;)

Interestingly, the Moon revolves around the Earth so slowly that it's path around the Sun actually looks like this:

main-qimg-c8ca8c109ecb9dacdaa8295c535d2bab.png


The common center of mass for the Earth and the Moon is inside the Earth, just barely. If it weren't it might be more appropriate to think of Earth/Luna as a double planet.
 
VMaxx said:
From what I can tell, the only reason they downgraded pluto to a non-planet is because they didn't have the guts to say all these others larger than it were planets too.
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Actually it was becauses there was no formal definition of a planet. So they went around to make one and Pluto lost out
 
bigdogchris said:
Then you would have the same definition applying differently based on people's feelings. When you bring feelings into science it's no longer science; therefore it does not belong.
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Or more like people dont like change and given its an arbitrary naming system there really wasnt a valid reason to change the system for existing items? Again we arent talking hard physics here we are talking about a human naming convention based on arbitrary rules by crusty old dudes. How would you react if we suddenly decided to start calling cows fish instead of mammals because we redefined what it meant to be mammals? Youd be justifiably confused and upset.

In the end of doesnt really matter wtf we call it. Might as well call it a anal bead and suggest the sun needs more lube. Would have the same effect on the universe...diddly squat.

sfsuphysics said:
But apparently people implode if we don't call Pluto a planet... case in point, this thread.
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Naw I dont think anyone is freaking out to that level. Annoyed? Almost certainly.
 
viper1152012 said:
Ceres......
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Wrong. Ceres is smaller than Pluto. A quick Google search on the subject confirmed what I had already known. Several sources cite Ceres as being smaller than Pluto, and all the information I could find that was recent reaffirms that Pluto is larger than all the other dwarf planets by size. Eris is thought to have greater mass due to higher density than Pluto. Thanks for playing.
 
People can identify, in order, the Sun, the Earth, the Moon, then Pluto, and then Mars. Americans are equally stupid about the names and locations of all other bodies in the Solar system.

Size doesn't matter - fame, bitch! You aren't shit if no one knows who you are!
 
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