As the article explains, if you bring back Pluto you must include Eris too, and perhaps Makemake and Haumea if you ignore is not as round as expected, and who know how many other undiscovered small object near them. (And Ceres? I like Ceres.)
Anyway, 9 is not an option, you must choose 8 or 10+.
Pluto is grandfathered in through the collective Consciousness of society. Just treat it the same way as tomatoes, which are officially fruits but no child believes that crap.
> “One of the biggest flaws with the IAU definition is that you can have the same object in two different orbits,” says Kornfeld. “In one, it’s considered a planet, and in the other, it’s not considered a planet.”
It seems as though Pluto's primary problem is "clearing the neighbourhood." Given Pluto's orbit travels closer and further from the sun than Neptune, does Neptune also have the neighborhood clearing problem since it has not cleared Pluto?
In celestial mechanics, "clearing the neighbourhood" (or dynamical dominance)
around a celestial body's orbit describes the body becoming gravitationally
dominant such that there are no other bodies of comparable size other than
its natural satellites or those otherwise under its gravitational influence.[0]
The "Criteria" section of that article clarifies the question. Neptune holds Pluto in an orbital resonance, which qualifies as Neptune gravitationally dominating its neighborhood. Perfect, 100% clearance is not expected anyway, since that's basically impossible in a real, dirty world where things move around.
In addition to what other commenters said about orbital resonance: Neptune has approximately 20 times bigger radius and is about 10_000 (ten thousand) times heavier. This is comparable to difference in mass between a human and a hummingbird. Could we really call them "comparable size"? I'm not sure, this is not a particularly precise term, but I would say - no.
I'm in the same camp. I believe the classification of Pluto as a dwarf planet was arbitrary and inconsistent. I mean, it's been known as a planet for almost 80 years and suddenly we demote it?
I believe someone was trying to make a name for themselves here and ignoring the history of Pluto and its discovery.
The issue is that when we discovered Pluto we thought it was much bigger than it turned out to be. If it was as big as they thought then sure it would be a planet. As it is it isn’t even the most massive dwarf planet
Or alternatively, how would any conceivable definition not be equally "psuedo-scientific"? There isn't going to be a bright, shining line. Our own Solar System is complicated enough and if we could see out into the cosmos with equal detail the lines would get even fuzzier. Judgment calls are inevitable.
Literally say Pluto is a planet through the collective statements of parties involved.
This is like when English professors gripe about word usage in books. That's wrong, you can't do that. Then society at large does it and it becomes correct usage. We define our world.
It's basically a question of definition: we define Pluto as a planet and the others as Kuiper Belt Objects (KBO)
As human beings we're allowed to make these kind of decisions. We define ourselves to be outside of the animal kingdom when we're clearly part of it and a type of animal ourselves.
The question would be what are the specific rules that lead to that, and how you'd apply those rules outside of our own solar system. Any rule that just calls those distant objects KBOs is specific to our own solar system which is a silly rule to be making in a world where we already knew about hundreds of exoplanets.
The question at hand is "how do we define a planet" from a universal standpoint, because it hadn't really been defined beyond an "I know it when I see it" level and that was becoming a problem.
Objective rules that do not assume you're talking about our solar system are key here, and the serious proposals basically come down to 8 planets or dozens and growing, and from a practical standpoint the former was the obvious choice IMO since all it really affects is what gets focused on in general education environments.
If you just want to make an arbitrary decision that these things are planets because you want them to be as opposed to because they meet certain criteria, that's not useful to anyone.
I'm on team Pluto hear but no, the problem was that Mike Brown found like a dozen 'planets' and no one wanted to deal with that. It was closer to preventing someone from making a name for themselves.
That would include Ceres, Quaoar and Orcus as planets.
It's really hard to come up with a definition of a planet that includes Pluto but doesn't include Orcus. Orcus is very close to a mirror of Pluto that is 120 degrees out of phase. Even in name: Orcus is the Roman name for the Greek god Pluto.
Like I said: we define it so. Pluto is a planet, the rest aren't. Period.
Yes, there may be some scientific reasons why Pluto isn't a real planet, but considering its history I (and others) believe we should simply overrule that.
The three I listed are inside Pluto's orbit. Part of the time for the latter 2.
If you want to say that Pluto is a planet for historical reasons, that's fine. Just don't try to invent pseudo-scientific nonsense to justify it at the same time you are decrying psuedo-scientific nonsense.
> We could simply define Pluto as the edge of our Solar System and everything beyond its orbit a Kuiper Belt Object.
A Kuiper Belt Object not being a part of Solar System doesn't make any sense. A star system is the star + all objects that orbit it. Why would you arbitrarily exclude some objects that orbit the Sun?
> We could simply define Pluto as the edge of our Solar System and everything beyond its orbit a Kuiper Belt Object. There's nothing wrong with that.
There is because Pluto is inside the Kuiper Belt and just as much a part of it as all the other "planets" in there. There's nothing wrong with defining our solar system as has having 8 planets plus a bunch of other stuff.
Eris is bigger than Pluto, so if Pluto’s a planet then so is Eris. So you have 10 planets.
And then how many other Erises are still hiding? How many planets do we have then? It must be some very large unknown number!
Holding the true number of planets to be a large unknown number was anathema to many.
The demotion of Pluto was primarily motivated by a desire for the word “planet” to refer fixed, never-changing number of large bodies orbiting the sun.
> Eris is bigger than Pluto, so if Pluto’s a planet then so is Eris. So you have 10 planets.
Which is exactly how I remember learning it at the end of highschool (discovered during my junior year): Hey, did you know we just discovered a tenth planet?
> someone was trying to make a name for themselves
100%
Scientists try to coin new terms all the time. It’s great for the researcher if people actually use it. But why do that when you can just sign your name on a term everyone already uses?
Redefining “planet,” from the 9 culturally accepted symbols into something else, was a swindle. “Things that clear their orbits” could have been TTCTOs. It happens all the time, coining precise terms for things. Why should this one have been any different? The public was right to push back and to protect their mythology from the unwelcome incursion.
The asset lost in this in this case is from the commons. That is, the ability to say "the ninth planet" or "the planet Pluto" without incurring smug harassment from legions who probably couldn't explain what the IAU is.
It’s completely unsurprising to deal with grammar policing over substance, but…
In terms of financial motives, I would reason that a motive for extending the term “planet” to cover the innumerable large objects orbiting other stars would have been as a better sales pitch to Congress. Studying “planets” lightyears away was a sort of brand hack which would have driven more funding. And when the “planets” was established as comprising a virtually infinite set, rather than simply a list of 9 known objects, the nomenclature collapsed in its usefulness, which is why the IAU started looking for a way out of its own hole.
However, as the article here discusses, the IAU’s approach has pretty much failed. It doesn’t hold up to scrutiny as a thing that’s meant to be usefully applied. How exactly do you confirm that all of those exoplanets have actually cleared their neighborhoods, or is the truth that it never actually mattered to anyone in the field?
Have any scientists or agencies written papers or reported to Congress that they discovered or studied some exoplanet — using public funds — when in fact they had no way of confirming whether its neighborhood was cleared? It sounds completely improper to me, but the reality is that it never really mattered.
The problem with demoting it lies in its beauty. Pluto is beautiful and interesting. We want it to be important. But instead of being the "last of the planets", maybe instead it should be the first of the dwarf planets.
Okay, so Pluto should be a planet, but then are you fighting for planetary classification of Ceres? Eris? Haumea, Makemake, Gonggong? Quaoar, Orcus, Sedna, Mani, Achlys, Aya, Chiminigugua, Varda, Ixion, Goibniu, Ritona, Uno, Varuna? 2005QY182? 2002XW93? The other 200-10000 that is very likely to lurk out there?
If you aren't you are totally inconsistent and just want what you were taught in elementary school be true.
I think of them more as by properties: Mercury hasn't even an atmosphere, it's too close to the sun; Venus is a hot earth so it sits closer than us; then comes its sister planet Earth; Mars is cool by comparison and sits further away than we do. Jupiter and Saturn are harder but sit before the ice giants Uranus and Neptune, again making logical sense. Whether Jupiter or Saturn comes first, I guess there's some memorisation, with or without some sentence about it
I can solve this! What is incompatible with being both a dwarf planet and a major planet? Peter Dinklage is both a dwarf actor and a major actor. Just acknowledge that Pluto is both too. You're welcome.
> “One of the biggest flaws with the IAU definition is that you can have the same object in two different orbits,” says Kornfeld. “In one, it’s considered a planet, and in the other, it’s not considered a planet.”
No, there is no flaw in this, and moreover there is nothing new in this. This is how it has always been, it is not something invented recently.
In the Solar System, there are 3 Mercury-sized satellites and other 3 Moon-sized satellites, besides the Moon. If they had not been in their orbits as satellites, they might have very well been planets. Therefore the old definition of "planet" also depended on the orbit of the body, not only on the size and shape of the body.
Most of those satellites are bigger than Pluto. Triton, the biggest satellite of Neptune, had been in the distant past another planet with an orbit close to Pluto, but it was captured by Neptune and it has become a satellite. Otherwise it would have remained a "dwarf planet", orbiting close to Pluto.
The current definition of "planets" and "dwarf planets" is fine.
If anything, there are too few planet classes, not too many. A more useful classification is into big planets, medium planets and small or dwarf planets, where the Solar system has 4 big planets, 4 medium planets, and a lot of small planets.
The big planets, i.e. which are big enough to retain the volatile chemical elements, like hydrogen and noble gases, not only the refractory elements, have a very different chemical composition from the medium planets, and this difference will also exist in any other stellar system that has condensed from gases like those at the origin of the Solar System, with more oxygen than carbon (there exists the possibility of stellar systems with a different chemical composition than the Solar System, formed by condensing from gas mixtures with more carbon than oxygen).
I‘m seeing this classification for the first time, but it sounds very reasonable and feels like it should have been like that. Is it your idea or is there any story behind it?
We already have the terms "rocky planet" and "gas giant" that pretty much cover it. The only thing missing is an official IAU decision which, well, would have even less effect than the Pluto thing I'm guessing, since it would just be introducing a sub-division in the category.
Since the Moon's orbit is always concave towards the Sun, one could even argue that the Moon is a planet, not a satellite, it just happens to have an orbit that is closely coupled to that of another planet, Earth.
As I understand it, in fact, there was discussion about defining systems like Earth-Moon as double planets, but that didn't make it into the final definition.
I have heard people argue that we are in fact in a kind of binary planetary system. No other planet has such a large satellite relative to its size, until you get to the likes of Pluto etc.
The Earth is closer but I don't think there's any good argument to say it's actually a binary system. Notably the Earth-Moon barycenter stays inside the Earth, and the Sun-Jupiter barycenter doesn't stay inside the Sun. But barycenters are too easy to get outside of objects anyway.
As I understand it, one suggested "double planet" definition was that the barycenter would have to be outside both objects. Earth-Moon doesn't (quite) satisfy that condition, but for example, Pluto-Charon does.
The Earth-Moon system is certainly anomalous within our Solar System. There is no such equivalent among the three other rocky planets, and while there are large moons around the other planets, the planets themselves are far larger.
I assume you're not including Pluto-Charon here (presumably since Pluto is now demoted to "dwarf planet")? Their mass ratio is only about 8:1, which is far smaller than Earth-Moon, 81:1.
The Sun's gravitational pull on the Moon is always stronger than the Earth's. (Do the math and see--on average the Sun's pull is more than twice as strong as the Earth's.) So the net acceleration of the Moon is always towards the Sun, never towards the Earth.
> The current definition of "planets" and "dwarf planets" is fine.
It’s serviceable, but is it ideal?
What’s the scientific advantage in categorising “planets” and “dwarf planets” as two separate categories, compared to unifying them into a single category (possibly while retaining the distinction as two different subtypes of “planet”)?
Which system would be more scientifically useful? Which would be more parsimonious?
The current set of planets, we are quite confident to be complete, there are no more planets out there. The set of known dwarf planets is likely to be incomplete, we think there are many more out there. I think that's a useful distinction.
What I don't get in this is why is it wrong to leave off the "dwarf" adjective? We drop adjectives all the time once the specific subject is identified.
You know, this is really just a fantastic opportunity to realize the phenomenal psychological power of "headcanon". Who cares if Pluto is or is not tagged with the word "planet" by some organization you know effectively nothing about, have no control over, has no control over you, and couldn't so much as move a pebble on the planetary body in question any time in the next 20 years, if not more?
Have whatever emotional relationship you like with "Pluto" and don't wait around for others to validate it. It's fine. Nobody can stop you. I'm a bit fond of Ceres myself. Nobody can stop me. Nobody needs to approve it. Take control. Write your own headcanon.
I agree, call whatever you like whatever you want. Just don't expect schools to teach that to anyone else. We get enough of that from the folks who want to replace science class with "God did it".
Maybe one day we'll know, but for now at least that's a question for theologians and philosophers. I'm content to leave questions about what lies outside of our universe to them.
In case anyone was curious, the Moon is bigger than Pluto. Pluto's 2/3 the size of the Moon. If any dwarf planet should be upgraded to a planet, it's Eris. Eris's diameter is over 600km bigger than Pluto's.
Pluto orbits center of combined masses of itself and Charon, which does not lie within either of them. Also, they are both tidally locked to each other, just like Moon is tidally locked to Earth.
In order to be defined as a planet, an object needs to meet 3 criteria:
- Orbits a star (Pluto does and I assume that's what you were asking about)
- The object has enough mass to pull itself into a sphere (meets this criteria)
- The object has enough gravity to have cleared its nearby orbit of debris and other objects
Neither Pluto nor Eris qualify for a planet because of that last one and, like I mentioned, the Moon has more mass than Pluto and Eris. The Kuiper belt objects all have this issue, but my point was that dwarf planets are pretty small - especially compared to other objects around Sol.
Because the IAU does not uniquely hold claim to undeniable, universal, transcendent truth that should be received without question or doubt -- or even healthy scientific disagreement -- alternate planetary definitions exist. In at least one of them, both Pluto and the Moon are planets.
The main objection to calling Pluto a planet appears to be that if Pluto is a planet then up to about 200 other objects should also be called planets, that the list would be of unknown size and regularly changing.
That's an objection? No, that's a benefit! I think it'd be awesome to be regularly discovering new planets.
"Discovering new planets" only has the cachet it does because there are so few of them, and they are individually so significant. It would quickly lose that significance if there were hundreds of them. To be precise, it would acquire exactly the significance it actually deserves, but having diluted the meaning of "planet" as applied to the big eight in the process. We would soon want another name for the originals to compensate.
We can still be reasonably excited about discovering new things in the solar system without pretending they're in the same category as Earth and Neptune.
With or without the IAU definition, you still end up with innumerable planets.
Scientists regularly claim to have found planets orbiting other stars. They do this even though they have no way to verify that their neighborhoods have been cleared.
And yes, you can decide that some particular things are special. That’s why culture is a big part of this. Many people consider Pluto to be special even though they are well aware that it’s not the only one out there, and that’s why they refer to it as a planet.
The idea that there would be too many planets isn’t really a problem that needed solving. Would we start classifying every dinosaur as either a T-Rex or a triceratops because otherwise there would be too many dinosaurs? It’s plainly ridiculous.
That's sort of what bothered me the most at the time. It seemed like the argument was that it was "emotional" or something to keep Pluto a planet when there might be so many of them. But I never understood why it was less "emotional" to insist that a planet be a certain size or that there should be a certain number of planets.
It is emotional reasoning to want Pluto to be an exception to an otherwise universal definition, because the reason for the exception are the emotions of some people.
Picking any arbitrary generic definition and applying it universally is less emotional, because there is no emotional reasoning necessary to explain why any object is or isn't a planet.
One of the parts that makes people emotional is that they’re plainly being lied to about the premise of needing a universal definition.
Scientists just ignore the rule about neighborhoods at times for convenience — how else would you claim to have found an “exoplanet” if you cannot also rule out “exo-dwarf-planets” in its neighborhood?
People can tell when a rule was added for an unstated reason. It’s a sort of appeal to authority rather than a scientific claim. That’s dishonest, and people push back when authorities are dishonest with them.
“We don’t make the rules, this is just what a planet is now. Wait, did you say we do make the rules? No, of course we didn’t vote on what our scientific result should be… that would be unscientific. We ARE science.”
> One of the parts that makes people emotional is that they’re plainly being lied to about the premise of needing a universal definition.
This makes no sense to me, can you explain WHY a universal definition is not needed?
> Scientists just ignore the rule about neighborhoods at times for convenience — how else would you claim to have found an “exoplanet” if you cannot also rule out “exo-dwarf-planets” in its neighborhood?
I might be missing a more specific critique, but IIUC, this question only makes sense to me if you presuppose that classifications must never be updated. Because otherwise, the solution is that you do the best you can with the data you have, and accept that better data might come along later and prove you missed something? The same way e.g. classifications in biology are frequently updated?
> People can tell when a rule was added for a specific reason that the authors don’t want to say outright. It’s a sort of appeal to authority rather than a scientific claim. That’s dishonest, and people push back when authorities are dishonest with them.
See, this is where you've totally lost me. I can't tell what people apparently can tell. So what is that specific reason? Do you have to wrap your allegations in so many indirect and allusions? This kind of conspiratorial-cryptic writing genuinely reminds me of flat earthers and qanon followers.
> We don’t make the rules, this is just what a planet is now. Wait, did you say we do make the rules? No, of course we didn’t vote on what our scientific result should be… that would be unscientific. We ARE science.
Did such a vote happen when Pluto got added? I genuinely don't know, but otherwise this objection makes no sense to me.
If you read Plato, you will see that defining words that already exist in some universal way is pretty much impossible. This is a humanities question, not a scientific one.
It was a fool’s errand or an act of deception to try to coerce “planet” to be a specialized word. The cracks are evident. The 2006 IAU definition doesn’t work.
Specialized words are great. They are important in science. “Planet” is not a specialized word and it has not been a specialized word for hundreds of years. Scientists did not need to somehow coerce “planet” into a specialized term to continue doing science—and if they did, there was still no reason to bother non-specialists about it, since science is its own domain where terms can be used in specialized ways.
> If you read Plato, you will see that defining words that already exist in some universal way is pretty much impossible. This is a humanities question, not a scientific one.
Nope. Just like it is okay for scientists in the field of biology to change the definition of "species" as used in their field, it is okay for the same to happen for the word "planet", even if the general public large then argues everyone should use the updated definition in everyday language. That's how language happens and evolves, and that's how we got these words! If this were not the case, Pluto would never have been added as a planet. You were okay with every change until that point - yeah, of course you agree with the changes up to what you were taught, even if there's no argument for what makes them different!
You have to understand: there's no conspiracy behind the IAU that's making people argue against you! It's literally just individual people disagreeing with your disagreement.
---
Regarding your edit:
> To help you to read more carefully and to apply context clues, the following is a quote from the article that this thread is about.
> > To its detractors, the IAU definition seemed crafted with a specific intent. “A reason was invented to exclude Pluto,” says Kornfeld.
In the article, I see literally no reason given by Kornfeld to assume anything but an honest disagreement. Okay, great, they think the definition should fulfill a requirement that the majority apparently doesn't see as necessary. How do they get from this to people inventing a reason to specifically exclude Pluto? There's no reason given to assume bad faith?
Deciding the color of the bike shed is easier than making important decisions about the building it sits next to. It's a well-known phenomenon https://en.wikipedia.org/wiki/Law_of_triviality
The actual problem here is weirdly aggressive nerds who are incapable of nuance, and insist that an astronomical classification (Pluto is not a planet by the IAU definition) should be used in non-astronomical contexts.
Historically and culturally, Pluto is considered a planet. An IAU classification shouldn't be used to try and retroactively change that, because the IAU does not have control over history and culture. It's a fun fact (did you know that Pluto is not classified as a planet by astronomers?) not a diktat.
Similarly, a banana is 'officially' a berry, which means that it is classified as a berry by botanists. This does not mean it is considered a berry in any other contexts. If you told someone you had made a berry crumble and it was filled with bananas, you would look strange. We have countless examples of this (often focused around food): a tomato does not belong in a fruit salad no matter what botanists say.
Different terms are used with different specificity in different settings. Language and culture and [older disciplines] are not governed by the rules of [newer disciplines or bodies]. If people with 'I love space' t-shirts would stop "um actually"-ing, no one would have a problem.
While reading your comment it occurred to me that virtually all reporting on (or talking about) science involves applying it to an unsuitable context. Schrödinger's cat is probably the most prolific example of this.
Scientists are constantly trying to encroach on areas that aren’t the domain of science in an attempt to expand their power, so this confusion is unavoidable and indeed deliberate.
Which would make the article's subjects "weirdly aggressive nerds who are incapable of nuance, and insist that" a non-astronomical definition be used in an astronomical context.
The term "fish" is a case in point. Traditionally, the term means a creature which lives underwater, which would include whales and dolphins, and indeed used to, despite being mammals.
It gets worse. Whales and dolphins are more closely related to certain fish than those fish are related to some other fish. (As are we by the way.) There are also some fish, such as lungfish or certain eels which can spend more time out of water than whales and dolphins can. Some fish can even breathe air, which undermines another assumption about whales etc.
For some reason, I rarely hear fewer people objecting to jellyfish or shellfish being referred to as fish, even though these are more distantly related to fish than mammals are.
So biologically, the term "fish" doesn't make much sense.
That was quite funny. I think my point is that terms are not always as precise as people think they are.
As others have stated, there appears to be some kind of spectrum. Some of the inner planets have more in common with the moons of Jupiter and Saturn in some regards, than they do with Jupiter and Saturn themselves. For a start they have a surface that can be landed on. (Maybe not so much in the case of Venus or Io!!!)
Pluto's most obvious problem is that it is too similar in size to a large number of other objects. But it does have some resemblances to planets and larger moons. I'm not keen on the phrase "dwarf planet" because it makes me think of objects that are much smaller than Pluto is.
> Historically and culturally, Pluto is considered a planet.
A very brief period of history. Give it 50 years and the number of people who will call it a planet will be close to 0.
Let's not overstate Pluto's significance in culture. People call it a planet only because that's what they were taught in school. Not because of other (very few) cultural references. As it has been dropped from the curriculum, so shall it be dropped from people's minds.
Compared to the other planets it's rarely referred to in stories, etc. It has very little significance in today's culture beyond the fact that it was taught in school.
That's not the case for something like Jupiter. If they decided tomorrow that gas giants are no longer planets, it will remain in arts and culture. Pluto? Highly unlikely.
This is not insignificant. The period of Pluto's planethood represents just about 0.76% of recorded human history, but that does cover around 7% of the total number of people who have ever lived, about 10x the 'average'. Of course a lot of culture comes out of that. I think the 20th century will be important to historians for a very very long time.
> The period of Pluto's planethood represents just about 0.76% of recorded human history, but that does cover around 7% of the total number of people who have ever lived, about 10x the 'average'. Of course a lot of culture comes out of that.
It's an odd way to analyze it. Plenty of things have been known for longer and it doesn't bother us if they're not taught in school, etc.
> When people stop referring to Pluto as a planet, it will cease to be one.
I'm not disagreeing. What I'm saying is that compared to most other planets, people are going to stop referring to Pluto as a planet, by the mere fact that they'll stop teaching it in school. It has no cultural momentum unlike Mars, Venus, etc.
Why 1000 km radius? I know that 1000k diameter might be important for cold bodies to keep their equilibrium, but what does 1000km radius give?
Because honestly anybody who played stuff like KSP RSS or any space game taking place in our solar system represented at scale with adequat orbit weirdness probably told themselves "that's Pluto? Ok i get it, not a planet".
Why not just have it be rounded under its own gravity? Collapse two rules into one. If nice round systems with clear boundaries is what you're going for
Pluto as one of the outer Canadian planets in the Canadian solar system, which as you now know is part of the Canadian Galaxy is realy such a trifling concern back on one of the Canadian Continents that contains Canada proper the center of Universal Canada, but since there is dissent on it's status something can be done through a referendum.
go ahead,laugh, but wait till google AND wikipedia both come on board
The problem is that the word “planet” refers both to cultural symbols — mythology, gods, archetypes, and the heavens — and to objects of scientific study. Those are different domains, and one of them is cultural heritage, and the other is irritating when it tries to infringe on the first one.
There’s no need for a god complex. Stop picking and choosing which planets are real. Scientists can create their own, more precise words for things. Planets are sacred. Things that clear their orbits are not.
You can’t subdue the public into giving up their gods out of difference to science — you’re just losing people.
I think not quite, although many planets have the names of the gods. They called them planets due to their motion, so it is still called that. The use of the same word in different contexts can have different usages and different (but sometimes related) meanings. "Planet" is used differently in astrology than it is in science; this isn't a contradiction (although, like any words, can sometimes result in confusion if you do not make the meaning clearly).
Why would a change today be such a violation of a sacred concept, when Pluto was added not even a century ago? If anything, it seems like the scientists back then had a god complex, and this would be rectifying their mistake.
Scientists can do whatever the like. The problem is when they try to exert control over other scientists and members of the general public. We have both freedom of speech and freedom of association, which means the IAU has no place governing my own speech, and it’s irritating that so many people seem gleeful to tell me otherwise.
How is the IAU trying to exert control or asserting any authority to govern your speech? I'm really having trouble seeing how the IAUs actions are in any way unusual for this kind of scientific organization, so please be specific about the consequences you expect to suffer for not following along.
And more importantly, why does the incredibly recent addition of Pluto to the list of planets not fall under scientists "try[ing] to exert control over other scientists and members of the general public"? You'd have a point if the planets were set in stone for hundreds of years, but as-is I can't follow your logic why one is okay and the other is not.
Perhaps the IAU didn’t attempt to exert any influence over the general public and perhaps they have had nothing to do with the legions who have since been irritatingly telling people that their words are scientifically incorrect, as if the IAU is an infallible god of science and that everyone must heed the IAU at all times regardless of whether they are practicing science at the particular moment.
We don’t have a problem with armchair scientists correcting people about the 1930s discovery of Pluto and how it was discussed at the time, we have a problem with armchair scientists being aggravating when people want to engage with the idea of Pluto today and refer to it as a planet.
Yes, perhaps people follow their own thoughts and opinions, so perhaps they understand and accept the IAU's explanation. Just like people less than 100 years ago perhaps accepted the explanation why scientists are suddenly adding a new ninth planet!
But I have a feeling that the problem you see is just a fairly normal social mechanism: if you use words differently from the majority of people, you will keep getting corrected because:
- some people might be genuinely trying to troll/aggravate you the way you're describing
- BUT: others might genuinely think you've made a mistake and try to correct you, unaware of any discourse
- and finally, other people might just disagree and attempt to discuss
No conspiracy is necessary to meet plenty of people who disagree, and the level of accusations you're throwing around tells me you might not be able to clearly categorize everyone.
I do accept the IAU’s explanation. It’s their definition, it’s none of my business, and I’m not accountable for using it myself.
Even if the person correcting you isn’t acting like an overexcited 13-year-old jumping up to correct someone about it, you must agree that as a point of discussion — as a matter of good taste and manners — telling someone that Pluto isn’t a planet is just terribly boring by now, and if that is stated as a response to something the person was trying to say, there’s a risk that attention and energy is being diluted from the actual point? Of course it happens earnestly, but there are still all of the other times and ways that it happens.
Pluto was only discovered in the 1930s. The only cultural heritage of Pluto as a ‘planet’ is a few decades of science schoolbooks, but going by these comments you'd think it's been in the same list as Jupiter since the Babylonians.
Herschel put Uranus on the map, so to speak. It is barely visible and never played a large part in ancient astrology/astronomy (I use both terms here as they were not separate at the time.)
Unfortunately this is both a false dichotomy fallacy and an appeal to extremes.
1. Yes, there are culturally significant things that have happened since the 1930s, including the discovery of Pluto and its designation as being a planet. In fact, in 2006, a group of people got together -- known as the IAU -- and they also performed a cultural act amongst themselves when they decided to stop calling Pluto a planet, undertaking a social process in adopting criteria for doing so.
2. If you would rather define a planet is a wandering star that's visible to unaided humans in the night sky, I'd respect that, and I kind of like the idea. It avoids the myriad issues that the article here discusses. The problem comes up when you police what other people call things, not when you decide to subscribe to the IAU of your own volition.
Easy to say when you didn't grow up counting Pluto as a planet. I still feel a bit depressed every time I tell my son "And there's... 8 planets in the solar system."
Because apparently sometimes between the moment I left elementary school and he went there, some dudes decided that Pluto didn't qualify as a planet after all.
As fare as I'm concerned, Pluto is a planet. I've got a hand-written note from Clyde Tombaugh that says so. Back in the mid-1990s, a year or two before he died, I write him asking about some astronomers who were starting to question it.
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[ 2.0 ms ] story [ 47.0 ms ] threadAlso, if you have the opportunity too see @plutokiller teach planetary science or give a lecture, I can recommend you do so!
Anyway, 9 is not an option, you must choose 8 or 10+.
What logical rule would you propose that allows Pluto to be a planet without also bringing in a bunch of others?
If you just want to arbitrarily declare things are they way you like them to be, religion is over there.
The rule would be: pluto is a planet, stay mad nerds
Next time you go to the grocery, grab a cucumber and a watermelon and try to find the differences.
So… planet Ganymede when? Or Titan?
It’s like saying Jupiter is not a planet because the Trojans exist.
In addition to what other commenters said about orbital resonance: Neptune has approximately 20 times bigger radius and is about 10_000 (ten thousand) times heavier. This is comparable to difference in mass between a human and a hummingbird. Could we really call them "comparable size"? I'm not sure, this is not a particularly precise term, but I would say - no.
I believe someone was trying to make a name for themselves here and ignoring the history of Pluto and its discovery.
How is it pseudo-scientific?
This is like when English professors gripe about word usage in books. That's wrong, you can't do that. Then society at large does it and it becomes correct usage. We define our world.
As human beings we're allowed to make these kind of decisions. We define ourselves to be outside of the animal kingdom when we're clearly part of it and a type of animal ourselves.
The question at hand is "how do we define a planet" from a universal standpoint, because it hadn't really been defined beyond an "I know it when I see it" level and that was becoming a problem.
Objective rules that do not assume you're talking about our solar system are key here, and the serious proposals basically come down to 8 planets or dozens and growing, and from a practical standpoint the former was the obvious choice IMO since all it really affects is what gets focused on in general education environments.
If you just want to make an arbitrary decision that these things are planets because you want them to be as opposed to because they meet certain criteria, that's not useful to anyone.
Pluto is the Princeps of Kuiper Belt Objects, the First Among Equals. It is the most honored KBO, even if it is not a planet.
still works, how bout that?
Why bother coming up with a pseudo-scientific requirements list for planets when these don't work for a large number of cases.
It's really hard to come up with a definition of a planet that includes Pluto but doesn't include Orcus. Orcus is very close to a mirror of Pluto that is 120 degrees out of phase. Even in name: Orcus is the Roman name for the Greek god Pluto.
Yes, there may be some scientific reasons why Pluto isn't a real planet, but considering its history I (and others) believe we should simply overrule that.
If you want to say that Pluto is a planet for historical reasons, that's fine. Just don't try to invent pseudo-scientific nonsense to justify it at the same time you are decrying psuedo-scientific nonsense.
A Kuiper Belt Object not being a part of Solar System doesn't make any sense. A star system is the star + all objects that orbit it. Why would you arbitrarily exclude some objects that orbit the Sun?
There is because Pluto is inside the Kuiper Belt and just as much a part of it as all the other "planets" in there. There's nothing wrong with defining our solar system as has having 8 planets plus a bunch of other stuff.
Eris is bigger than Pluto, so if Pluto’s a planet then so is Eris. So you have 10 planets.
And then how many other Erises are still hiding? How many planets do we have then? It must be some very large unknown number!
Holding the true number of planets to be a large unknown number was anathema to many.
The demotion of Pluto was primarily motivated by a desire for the word “planet” to refer fixed, never-changing number of large bodies orbiting the sun.
Which is exactly how I remember learning it at the end of highschool (discovered during my junior year): Hey, did you know we just discovered a tenth planet?
100%
Scientists try to coin new terms all the time. It’s great for the researcher if people actually use it. But why do that when you can just sign your name on a term everyone already uses?
Redefining “planet,” from the 9 culturally accepted symbols into something else, was a swindle. “Things that clear their orbits” could have been TTCTOs. It happens all the time, coining precise terms for things. Why should this one have been any different? The public was right to push back and to protect their mythology from the unwelcome incursion.
In terms of financial motives, I would reason that a motive for extending the term “planet” to cover the innumerable large objects orbiting other stars would have been as a better sales pitch to Congress. Studying “planets” lightyears away was a sort of brand hack which would have driven more funding. And when the “planets” was established as comprising a virtually infinite set, rather than simply a list of 9 known objects, the nomenclature collapsed in its usefulness, which is why the IAU started looking for a way out of its own hole.
However, as the article here discusses, the IAU’s approach has pretty much failed. It doesn’t hold up to scrutiny as a thing that’s meant to be usefully applied. How exactly do you confirm that all of those exoplanets have actually cleared their neighborhoods, or is the truth that it never actually mattered to anyone in the field?
Have any scientists or agencies written papers or reported to Congress that they discovered or studied some exoplanet — using public funds — when in fact they had no way of confirming whether its neighborhood was cleared? It sounds completely improper to me, but the reality is that it never really mattered.
If you aren't you are totally inconsistent and just want what you were taught in elementary school be true.
My Very Easy Method Just Speeds Up Naming Planets
And it was so convenient! Does anyone know a good alternate now that the P is gone?
Asteroid belt in between and the second asteroid belt (the Kuiper belt) on the outside.
Then the Oort cloud surrounding the whole thing as a shield to protect the system from alien incursion.
No, there is no flaw in this, and moreover there is nothing new in this. This is how it has always been, it is not something invented recently.
In the Solar System, there are 3 Mercury-sized satellites and other 3 Moon-sized satellites, besides the Moon. If they had not been in their orbits as satellites, they might have very well been planets. Therefore the old definition of "planet" also depended on the orbit of the body, not only on the size and shape of the body.
Most of those satellites are bigger than Pluto. Triton, the biggest satellite of Neptune, had been in the distant past another planet with an orbit close to Pluto, but it was captured by Neptune and it has become a satellite. Otherwise it would have remained a "dwarf planet", orbiting close to Pluto.
The current definition of "planets" and "dwarf planets" is fine.
If anything, there are too few planet classes, not too many. A more useful classification is into big planets, medium planets and small or dwarf planets, where the Solar system has 4 big planets, 4 medium planets, and a lot of small planets.
The big planets, i.e. which are big enough to retain the volatile chemical elements, like hydrogen and noble gases, not only the refractory elements, have a very different chemical composition from the medium planets, and this difference will also exist in any other stellar system that has condensed from gases like those at the origin of the Solar System, with more oxygen than carbon (there exists the possibility of stellar systems with a different chemical composition than the Solar System, formed by condensing from gas mixtures with more carbon than oxygen).
- a gang of dwarfs
- some rocky ones
- and gas giants
- and one star to rule them all
As I understand it, in fact, there was discussion about defining systems like Earth-Moon as double planets, but that didn't make it into the final definition.
Huh?
It’s serviceable, but is it ideal?
What’s the scientific advantage in categorising “planets” and “dwarf planets” as two separate categories, compared to unifying them into a single category (possibly while retaining the distinction as two different subtypes of “planet”)?
Which system would be more scientifically useful? Which would be more parsimonious?
Have whatever emotional relationship you like with "Pluto" and don't wait around for others to validate it. It's fine. Nobody can stop you. I'm a bit fond of Ceres myself. Nobody can stop me. Nobody needs to approve it. Take control. Write your own headcanon.
- Orbits a star (Pluto does and I assume that's what you were asking about)
- The object has enough mass to pull itself into a sphere (meets this criteria)
- The object has enough gravity to have cleared its nearby orbit of debris and other objects
Neither Pluto nor Eris qualify for a planet because of that last one and, like I mentioned, the Moon has more mass than Pluto and Eris. The Kuiper belt objects all have this issue, but my point was that dwarf planets are pretty small - especially compared to other objects around Sol.
That's an objection? No, that's a benefit! I think it'd be awesome to be regularly discovering new planets.
We can still be reasonably excited about discovering new things in the solar system without pretending they're in the same category as Earth and Neptune.
Scientists regularly claim to have found planets orbiting other stars. They do this even though they have no way to verify that their neighborhoods have been cleared.
And yes, you can decide that some particular things are special. That’s why culture is a big part of this. Many people consider Pluto to be special even though they are well aware that it’s not the only one out there, and that’s why they refer to it as a planet.
The idea that there would be too many planets isn’t really a problem that needed solving. Would we start classifying every dinosaur as either a T-Rex or a triceratops because otherwise there would be too many dinosaurs? It’s plainly ridiculous.
Picking any arbitrary generic definition and applying it universally is less emotional, because there is no emotional reasoning necessary to explain why any object is or isn't a planet.
Scientists just ignore the rule about neighborhoods at times for convenience — how else would you claim to have found an “exoplanet” if you cannot also rule out “exo-dwarf-planets” in its neighborhood?
People can tell when a rule was added for an unstated reason. It’s a sort of appeal to authority rather than a scientific claim. That’s dishonest, and people push back when authorities are dishonest with them.
“We don’t make the rules, this is just what a planet is now. Wait, did you say we do make the rules? No, of course we didn’t vote on what our scientific result should be… that would be unscientific. We ARE science.”
This makes no sense to me, can you explain WHY a universal definition is not needed?
> Scientists just ignore the rule about neighborhoods at times for convenience — how else would you claim to have found an “exoplanet” if you cannot also rule out “exo-dwarf-planets” in its neighborhood?
I might be missing a more specific critique, but IIUC, this question only makes sense to me if you presuppose that classifications must never be updated. Because otherwise, the solution is that you do the best you can with the data you have, and accept that better data might come along later and prove you missed something? The same way e.g. classifications in biology are frequently updated?
> People can tell when a rule was added for a specific reason that the authors don’t want to say outright. It’s a sort of appeal to authority rather than a scientific claim. That’s dishonest, and people push back when authorities are dishonest with them.
See, this is where you've totally lost me. I can't tell what people apparently can tell. So what is that specific reason? Do you have to wrap your allegations in so many indirect and allusions? This kind of conspiratorial-cryptic writing genuinely reminds me of flat earthers and qanon followers.
> We don’t make the rules, this is just what a planet is now. Wait, did you say we do make the rules? No, of course we didn’t vote on what our scientific result should be… that would be unscientific. We ARE science.
Did such a vote happen when Pluto got added? I genuinely don't know, but otherwise this objection makes no sense to me.
It was a fool’s errand or an act of deception to try to coerce “planet” to be a specialized word. The cracks are evident. The 2006 IAU definition doesn’t work.
Specialized words are great. They are important in science. “Planet” is not a specialized word and it has not been a specialized word for hundreds of years. Scientists did not need to somehow coerce “planet” into a specialized term to continue doing science—and if they did, there was still no reason to bother non-specialists about it, since science is its own domain where terms can be used in specialized ways.
Nope. Just like it is okay for scientists in the field of biology to change the definition of "species" as used in their field, it is okay for the same to happen for the word "planet", even if the general public large then argues everyone should use the updated definition in everyday language. That's how language happens and evolves, and that's how we got these words! If this were not the case, Pluto would never have been added as a planet. You were okay with every change until that point - yeah, of course you agree with the changes up to what you were taught, even if there's no argument for what makes them different!
You have to understand: there's no conspiracy behind the IAU that's making people argue against you! It's literally just individual people disagreeing with your disagreement.
---
Regarding your edit:
> To help you to read more carefully and to apply context clues, the following is a quote from the article that this thread is about.
> > To its detractors, the IAU definition seemed crafted with a specific intent. “A reason was invented to exclude Pluto,” says Kornfeld.
In the article, I see literally no reason given by Kornfeld to assume anything but an honest disagreement. Okay, great, they think the definition should fulfill a requirement that the majority apparently doesn't see as necessary. How do they get from this to people inventing a reason to specifically exclude Pluto? There's no reason given to assume bad faith?
Historically and culturally, Pluto is considered a planet. An IAU classification shouldn't be used to try and retroactively change that, because the IAU does not have control over history and culture. It's a fun fact (did you know that Pluto is not classified as a planet by astronomers?) not a diktat.
Similarly, a banana is 'officially' a berry, which means that it is classified as a berry by botanists. This does not mean it is considered a berry in any other contexts. If you told someone you had made a berry crumble and it was filled with bananas, you would look strange. We have countless examples of this (often focused around food): a tomato does not belong in a fruit salad no matter what botanists say.
Different terms are used with different specificity in different settings. Language and culture and [older disciplines] are not governed by the rules of [newer disciplines or bodies]. If people with 'I love space' t-shirts would stop "um actually"-ing, no one would have a problem.
This is the actual problem everywhere.
It gets worse. Whales and dolphins are more closely related to certain fish than those fish are related to some other fish. (As are we by the way.) There are also some fish, such as lungfish or certain eels which can spend more time out of water than whales and dolphins can. Some fish can even breathe air, which undermines another assumption about whales etc.
For some reason, I rarely hear fewer people objecting to jellyfish or shellfish being referred to as fish, even though these are more distantly related to fish than mammals are.
So biologically, the term "fish" doesn't make much sense.
As others have stated, there appears to be some kind of spectrum. Some of the inner planets have more in common with the moons of Jupiter and Saturn in some regards, than they do with Jupiter and Saturn themselves. For a start they have a surface that can be landed on. (Maybe not so much in the case of Venus or Io!!!)
Pluto's most obvious problem is that it is too similar in size to a large number of other objects. But it does have some resemblances to planets and larger moons. I'm not keen on the phrase "dwarf planet" because it makes me think of objects that are much smaller than Pluto is.
A very brief period of history. Give it 50 years and the number of people who will call it a planet will be close to 0.
Let's not overstate Pluto's significance in culture. People call it a planet only because that's what they were taught in school. Not because of other (very few) cultural references. As it has been dropped from the curriculum, so shall it be dropped from people's minds.
Compared to the other planets it's rarely referred to in stories, etc. It has very little significance in today's culture beyond the fact that it was taught in school.
That's not the case for something like Jupiter. If they decided tomorrow that gas giants are no longer planets, it will remain in arts and culture. Pluto? Highly unlikely.
It's an odd way to analyze it. Plenty of things have been known for longer and it doesn't bother us if they're not taught in school, etc.
When people stop referring to Pluto as a planet, it will cease to be one.
Until then, we are living in a reality in which Pluto both is a planet and is not a planet, depending on the context.
I'm not disagreeing. What I'm saying is that compared to most other planets, people are going to stop referring to Pluto as a planet, by the mere fact that they'll stop teaching it in school. It has no cultural momentum unlike Mars, Venus, etc.
I see what Schindler did there!
- not a star
- not orbiting a planet
- roundish
- greater than 1000km radius
That would restore Pluto to its rightful place and add Eris.
Because honestly anybody who played stuff like KSP RSS or any space game taking place in our solar system represented at scale with adequat orbit weirdness probably told themselves "that's Pluto? Ok i get it, not a planet".
There’s no need for a god complex. Stop picking and choosing which planets are real. Scientists can create their own, more precise words for things. Planets are sacred. Things that clear their orbits are not.
You can’t subdue the public into giving up their gods out of difference to science — you’re just losing people.
And more importantly, why does the incredibly recent addition of Pluto to the list of planets not fall under scientists "try[ing] to exert control over other scientists and members of the general public"? You'd have a point if the planets were set in stone for hundreds of years, but as-is I can't follow your logic why one is okay and the other is not.
We don’t have a problem with armchair scientists correcting people about the 1930s discovery of Pluto and how it was discussed at the time, we have a problem with armchair scientists being aggravating when people want to engage with the idea of Pluto today and refer to it as a planet.
But I have a feeling that the problem you see is just a fairly normal social mechanism: if you use words differently from the majority of people, you will keep getting corrected because:
- some people might be genuinely trying to troll/aggravate you the way you're describing
- BUT: others might genuinely think you've made a mistake and try to correct you, unaware of any discourse
- and finally, other people might just disagree and attempt to discuss
No conspiracy is necessary to meet plenty of people who disagree, and the level of accusations you're throwing around tells me you might not be able to clearly categorize everyone.
Even if the person correcting you isn’t acting like an overexcited 13-year-old jumping up to correct someone about it, you must agree that as a point of discussion — as a matter of good taste and manners — telling someone that Pluto isn’t a planet is just terribly boring by now, and if that is stated as a response to something the person was trying to say, there’s a risk that attention and energy is being diluted from the actual point? Of course it happens earnestly, but there are still all of the other times and ways that it happens.
Most recent example I found was the Swatch MoonSwatch Collection [1], which includes the Sun, Moon, eight planets and Pluto[2].
1. https://www.swatch.com/en-us/bioceramic-moonswatch-collectio...
2. https://www.swatch.com/en-us/mission-to-pluto-so33m101/SO33M...
1. Yes, there are culturally significant things that have happened since the 1930s, including the discovery of Pluto and its designation as being a planet. In fact, in 2006, a group of people got together -- known as the IAU -- and they also performed a cultural act amongst themselves when they decided to stop calling Pluto a planet, undertaking a social process in adopting criteria for doing so.
2. If you would rather define a planet is a wandering star that's visible to unaided humans in the night sky, I'd respect that, and I kind of like the idea. It avoids the myriad issues that the article here discusses. The problem comes up when you police what other people call things, not when you decide to subscribe to the IAU of your own volition.
Because apparently sometimes between the moment I left elementary school and he went there, some dudes decided that Pluto didn't qualify as a planet after all.