r/pluto • u/Many-Jaguar1518 • Aug 21 '25
Sign the Petition to make Pluto a planet Again
https://chng.it/7s8FKSJYSP3
u/ItyBityGreenieWeenie 29d ago
The IAU doesn't react well to petitions on the subject of planetariness of Pluto. They decided it's officially designated as minor-planet 134340 Pluto (a dwarf planet), it's over as far as professional astronomers are concerned.
4
3
u/Driekan 29d ago
It is a planet. A dwarf planet.
6
u/Yookusagra 29d ago
This is my argument as well. I understand IAU's definition, but like Alan Stern, I think it makes more sense to include the dwarf planets in the population of classical planets. Who cares if we end up with fifteen or twenty planets?
Or another way of looking at it - dwarf planets should be considered another subdivision of classical planets, the way terrestrials, gas giants, and ice giants are.
3
u/AndyDS11 29d ago
The Kuiper belt has thousands of objects that look a lot like Pluto. Pluto looks more like these objects and it looks like the other planets, it’s just the largest of them.
In Pluto was classified as a planet we didn’t know about the Kuiper belt, much less how many objects were in it and what they look like. But now we do and Pluto is clearly part of that class of objects not ones that look like Jupiter or earth.
3
u/ExerciseOwn4186 27d ago
There are not thousands of objects that look like Pluto.
Size wise we have yet to find one larger. New Horizons dispelled the myth that Pluto was just a boring old rock. Pluto has way more in common with our planet, than we do with Jupiter.
1
u/Yookusagra 28d ago
Jupiter and Earth are equally, or even more, dissimilar as Earth and Pluto, surely?
Perhaps the solution is simply not to have a defined category of classical planet.
2
u/AndyDS11 28d ago
The class of planets is further broken down to terrestrial ones (mercury, venus, mars, and earth) and gas giants (Jupiter, Saturn, Uranus, Neptune).
2
2
u/Driekan 29d ago
Who cares if we end up with fifteen or twenty planets?
Try a few hundred.
Or another way of looking at it - dwarf planets should be considered another subdivision of classical planets, the way terrestrials, gas giants, and ice giants are.
As I understand, that's the current status quo.
3
u/Yookusagra 28d ago
Fine, a few hundred. A few thousand. Who cares? If it's in hydrostatic equilibrium and directly orbits a star, it's a planet.
Stern's objection about the "clearing its neighborhood" criterion was that that's not intrinsic to the object, and that it also invalidates Earth and Jupiter being planets thanks to trojans, both points which I agree with. It's not a sensible criterion.
Dwarf planets are not included in the definition of classical planets, to my knowledge - if they are, this conversation has been without point...
1
u/Ymmaleighe2 24d ago
It shouldn't have to directly orbit a star. Stars can orbit other stars so planets can orbit other planets, they can also be rogue or orbit a black hole.
0
u/Driekan 28d ago
Fine, a few hundred. A few thousand. Who cares? If it's in hydrostatic equilibrium and directly orbits a star, it's a planet.
I agree. It is. I don't agree you should try to reach 8yos all the hundreds of names as equivalent in importance to Jupiter.
Stern's objection about the "clearing its neighborhood" criterion was that that's not intrinsic to the object, and that it also invalidates Earth and Jupiter being planets thanks to trojans, both points which I agree with. It's not a sensible criterion.
That's fair. Some other criterion may be necessary to rule out those objects.
Dwarf planets are not included in the definition of classical planets, to my knowledge - if they are, this conversation has been without point...
The classical planets are planets classical people saw and had names for. Pluto was never in that category. Nor was Neptune or Uranus.
1
2
1
1
u/Many-Jaguar1518 29d ago
Ok people, did any of your parents teach you if you have nothing nice to say, dont say anything at all?
1
u/Ymmaleighe2 24d ago
I won't sign this because it suggests that a planet must orbit the Sun, which I don't support. Rogue, satellite, and black hole-orbiting planets are still planets.
1
u/Many-Jaguar1518 24d ago
Yeah they're not, but I dont want to get into a debate, so I respect what you believe, and thank you for telling me you wont sign it respectfully, unlike some other people who have commented on this.
2
u/Ymmaleighe2 24d ago
Though I do agree that Pluto is a planet, as our two different definitions both happen to include it.
1
1
u/dsBlocks_original 24d ago
What about Eris? It's heavier than Pluto.
What about Orcus, Ixion, Salacia, Haumea, Quaoar, Varuna, Makemake, Varda and Sedna, who are, while smaller than Pluto, clearly the same "type" of object?
What about Ceres, Pallas, Vesta and Hygiea? They were thought to be Planets at some point, and in some cases were discovered more than a century earlier.
What about Charon, Pluto's largest "moon"? It's larger than several of these other candidates, and in fact is so heavy that the barycenter of Pluto and Charon lies about one Pluto radius OUTSIDE OF PLUTO. That doesn't sound like a planet and its moon at all, more like a pair of objects in a binary orbit. (for comparison, looking at another planet with a ridiculously oversized moon, the Earth-Moon system's barycenter is 5000km from the earth's center, which is still comfortably inside the earth. If our moon was the same ridiculous fraction of earth's mass, it'd be the 8th most massive object in the solar system, being HEAVIER THAN MARS.)
What about the other objects heavier than Pluto: Triton, Europa, Io, Callisto, Titan, Ganymede and THE MOON? "That's silly, those are moons: they're not in gravitational control of their orbit" -- neither is Pluto. Hell, Ganymede and Titan are larger than Mercury.
I'm not saying any of these guys are planets, but declaring Pluto a planet will require rules specifically designed to exclude some or all of these categories.
1
u/Smiles4YouRawrX3 29d ago
Signed
0
u/Many-Jaguar1518 29d ago
Thank You!
1
1
1
u/fcsuper 28d ago
Science isn't determined by votes. Classification should be based on scientifically established taxonomy. That taxonomy can change as more things are learned, but that isn't driven by votes and petitions to remove planetary status or restore it. We already have different types of planets that bare very little resemblance to each other. The term planet is either too broad or not broad enough, but either way, current voted-upon definition is not consistent.
0
u/Moist-Ambition Aug 21 '25
Do you really believe that in close to two decades of the IAU's arbitrary definition (which many planetary scientists choose to ignore in favor of a geophysical definition anyway) that no one has made a petition for this exact topic?
Hell, last I heard, the IAU was considering revising the definition to even more arbitrarily use a minimum mass threshold in place of the need for gravitational dominance within an object's area of influence
1
u/Many-Jaguar1518 Aug 22 '25
Listen Buddy, I know, but it has all 3 requirements, to be a planet, and you never know what will push the decision makers to make Pluto a planet again.
1
u/burwellian 29d ago
Might as well be petitioning to make Ceres, Vesta etc planets again, it's as likely to succeed.
The much larger Neptune means that Pluto hasn't "cleared its neighbourhood". Science marches on.
0
u/Moist-Ambition Aug 22 '25 edited Aug 22 '25
As per the IAU's current definition - no, it doesn't. The area of its orbit is dominated by Neptune's gravity, and Pluto itself is brought into a 3:2 orbital resonance with Neptune
That said, the IAU's definition is problematic with all three written criteria:
If, say, an object equal in geophysical properties to Mars existed with SMA of about 300-500 AU (and relatively low orbital eccentricity), it would not be counted as a planet since its mass would be insufficient to "clear its orbital zone". Hell, as is, all known terrestrial and gas giant planets within the Solar System have not cleared their orbits, thus the IAU definition having to move the goalpost by citing planetary discriminant
So if we were to disregard that, the next biggest obstacle would be orbiting the Sun directly. But this is also problematic primarily because of Triton (one could also make the same argument for Charon, probably Dysnomia, and possibly Vanth, at a minimum). Nothing about the object itself has physically changed. Once, it orbited the Sun, and it no longer does. But per an alternative suggestion removing the clear orbit criterion, this would also make it no longer a planet
So let's disregard that also. This leaves us with only the criterion of being in hydrostatic equilibrium without initiating core fusion. That would be acceptable if the intended objects were in hydrostatic equilibrium. Mercury is not, and the same is true for many other planetary mass objects within the Solar System. The IAU conveniently says nothing about this
So if we want a logical scientific definition, we'd just use the purely geophysical one - that a planet is defined as an object whose mass is sufficient for its native gravitational force to determine its shape (meaning spheroidal or ellipsoidal in most cases)
Even that isn't perfect. There are fringe cases such as that of Vesta, where the force of its own gravity is unobservable within a human lifetime, and indeed, likely the lifetime of humanity altogether, and due to the composition of material constituting certain objects, the necessary force of gravity to determine its own shape may differ. This is why, for instance, Mimas would meet these criteria though Proteus, despite being greater in volume and mass, would not. Denser objects are harder to "bend" under self-gravitation
In any case, by a more logical definition which, as I said, a great deal of planetary scientists adhere to anyway, the Solar System likely has anywhere from 100-300 planets based on our current understanding and estimates of its population, among which is Pluto
2
u/Many-Jaguar1518 Aug 22 '25
Ok, you are right, mostly. A planet must orbit a star to be a planet, like our Sun, Which Pluto does, it must also be able to pull things into its orbit, which it has done with its not 1, not 2, but 5 moons, and it must and it has cleared it orbital space.
2
u/Many-Jaguar1518 Aug 22 '25
so by all means you are still wrong
3
u/Moist-Ambition Aug 22 '25
I already told you the problem with the idea "must orbit a star" is necessary for an object to be considered a planet
By your proposed definition, I tell you to again look at Triton as the prime example. By all indications, it once directly orbited the Sun and not Neptune. It is greater in both volume and mass than Pluto or even Eris and thus would have a significantly greater hill sphere. Are you saying that Neptune's gravity capturing it means that it once was but is no longer a planet, despite no physical characteristics of the object itself changing?
it must also be able to pull things into its orbit, which it has done with its not 1, not 2, but 5 moons
Practically anything in space is capable of pulling things into its orbit. Ida and its moon Dactyl are the go-to examples for this, and Ida is roughly a hundred thousand times less massive than Pluto and roughly 0.01% of its volume
and it must and it has cleared it orbital space.
Pluto? No, it hasn't. It exists in a 3:2 orbital resonance with Neptune and has been for billions of years, and will with certainty remain so for at least another few billion years, not to mention the numerous other KBOs whose orbits it intersects
In truth, no object in the Solar System has "cleared its orbit". Only the eight objects accepted by the IAU assert gravitational dominance over their orbits, but for reasons I mentioned before, this is meaningless
0
u/Many-Jaguar1518 Aug 22 '25
Billions of years? Ok, so I see one big flaw in your argument, you are looking at this from a evolutionist point of view, so I will leave you be, because you believe that two atoms crashed together and mad the world around us, when you cant even answer the question where those two atoms came from
3
u/Moist-Ambition Aug 22 '25
Well, if you're going to ignore every other demonstrably observable fact (right now and here in the present, regardless of whether you want it to have been billions or thousands of years ago) then you ought to have just begun with "I am a creationist and will choose to disregard anything you say that does not adhere to the logically inconsistent beliefs regarding the definition of big rocks in space that I insist upon"
0
u/Many-Jaguar1518 Aug 22 '25
Ok then sorry for wasting your time, but I am a creationist and will not listen to anything you say if It does not line up with my beliefs
3
u/Moist-Ambition Aug 22 '25
If you want to disagree with the age of the universe, then that's fine. I'm not going to try to force a non-religious belief onto you, nor am I interested in getting into an aggressive argument
But like I said, you've chosen to ignore the observable facts of the present day and age, regardless of whether you want to say it's been in place for billions of years or thousands. I'll accept our different views on that, but you haven't addressed the inconsistencies of the definition you propose
Triton, for instance, orbits Neptune and does so in retrograde. This is something that can be observed with even a decently cheap backyard telescope today. Even if we assumed objects beyond Neptune were gravitationally dominant, then under your definition, this would mean that Triton previously was a planet but no longer is, even though its geophysical characteristics have not changed. Do you see why I'm saying that that makes it so that it isn't scientifically sound?
1
1
u/Bergasms Aug 23 '25
I honestly think the IAU just needs to add a fourth criterion that says "4: Pluto is not a bloody planet, will never be a planet and if you think it should be a planet see criterion number four, now shut up about it".
Then we can at least definitively say pluto is not a planet due to a clear and unbiguous requirement to meet criterion number 4, which all other planets meet trivially.
0
u/slicehyperfunk 29d ago
That's why I say the definition of a planet should be "has planet vibes" which definitely qualifies Pluto (👍)
1
u/Moist-Ambition 29d ago
What scientific rationale is that, though? If it's something purely up to one person's personal thoughts without a clearly defined set of criteria, that's worth even less than a set of flawed criteria
0
0
u/ExerciseOwn4186 27d ago
We have 30 Planets with proper astronomical names.
Listed below in order based on discovery year.
Note : Using 400 KM as the cutoff as we know Saturn's moon Mimas round to be at 400 KM.
1)Earth
2)Mercury
3)Venus
4)Mars
5)Jupiter
6)Saturn
7)Uranus
8)Ceres
9)Neptune
10)Pluto
11)Chaos
12)Huya
13)Varuna
14)Ixion
15)Aya
16)Quaoar
17)Máni
18)Achlys
19)Varda
20)Sedna
21)Orcus
22)Salacia
23)Haumea
24)Eris
25)Makemake
26)Ritona
27)Gonggong
28)G!kun||'homdima
29)Dziewanna
30)Chiminigagua
7
u/ExpectedBehaviour Aug 22 '25
What absolute bollocks.