You know, categories are arbitrary, subjective, and human constructed, right? This is an excellent illustration of the idea.
I appreciate that each example includes a tidy, neat rationalization, so we can see that the rationalizations are arbitrary, too. I just wish he’d do the same thing for categories of DNA sequences so I’d have an excuse to use it in my classes.
Man, seriously? Ten years on I thought StevoR might actually be over it and you’re going to set him off again?
;-)
AFAIK in ultratraditionalist view the Sun and Moon were also considered “planets”, or wandering stars, a subset of stars. Hence the seven classical planets.
As for the simplistic view, I understand that stars (by whatever exact definition) are usually (since the Copernican revolution, and notwithstanding the ultratraditionalist view mentioned above) exempted from the concept of “planets”, by convention if nothing else. This includes the view where all rounded or “planetary-mass” bodies orbiting a star are planets.
I would support this with the argument from how do adjectives work?
A tall man is a man.
A red car is a car.
A dwarf planet is a planet.
‽‽‽
@ 1
Actually it’s 20 years (already?!).
I’m so old I fucked up my own joke.
https://en.wikipedia.org/wiki/IAU_definition_of_planet
@3 Reginald Selkirk
Aaaaaaackchually, “dwarf” here is not an adjective but part of a compound noun.
An interesting planet is a terrestrial planet young enough to retain a magnetic field who is not a super-Earth or mini-Neptune big enough to retain an stmosphere (bigger than Mars) who orbits in the “Goldilocks zone” around a single star of the F, G or K class.
.
Current technologies makes it very hard to find such worlds unless they pass in front of the star as seen from us (less than 1% chance).
I do not bother to read articles unless a planet fulfills most of these criteria. Red Dwarf planets are common as dirt, and just as interesting.
Give me Von Neumann machines to process the dwarf planets and I will give a damn. Or throw the dwarf planets at Mars to add volatile substances.
(Lightbulb moment) -True AI will not be bothered by extreme cold or vacuum. We have found a safe place to park those superintelligences some people are so scared of.
@birgerjohansson
They may be bothered by boredom though.
Myself @ 8
This is not ‘solipsistic’, I just narrow the requirements to what makes Earth more fun than Venus and Mars.
I forgot- the rotational period needs to be short enough the oceans do not freeze over during the night.
I suppose we can call this narrowly defined category “not a deathworld”. (The film character Mickey 17 can terraform the other planets)
If I seem grumpy it is because of the goddamn Elon spreading unrealistic expectations.
Iasius @ 10
Let them have cats as pets. Keeping a fragile settlement safe in the face of a dozen restless moggies is a challenge.
Also, let them figure out the 42 question, it took 4 billion years last time.
You heard about Pluto? That’s messed up.
Someone already beat me to pointing out that the sun and moon were considered planets by Classical and Mediaeval astronomers. Sometimes comets too. Of course, to the ancients planets were just another type of star (“wandering stars”, hence planetai in Greek), so we really need another chart to define what “star” means…
An old flamewar, but I’ll bite.
The IAU definition is too constrained by the details of a planet’s location and not much about its physical properties. Unfortunately our track record of discovering exoplanets in unusual locations really started to pick up after that definition was put in place.
And yes, I am in the camp of lunatics who consider any gravitationally-rounded terrestrial, giant, KBO, dwarf, and rogue [exo-]planets to be planets.
beholder @15: Yours is not a lunatic position*, just a minority one. But those including dynamical properties are also defensible. Stellar systems are dynamic. Classifying the bodies therein (at least in part) dynamically is reasonable. One could cite ‘clearing the neighbourhood’, or simply classify them according to their kinetic energy. Pretty much the same outcome; Pluto et al are bit players. That’s not to say they aren’t of interest.
*Not the planetary definition position, anyway.
People like to complain that the current definition of planets doesn’t take into account their properties. And yet somehow it just so happens to work out that the eight largest masses around the sun are planets, and all the others are not. That’s what makes a category useful – when it lines up with other characteristics, making the choice of how to divide things a little less arbitrary.
Modern is a good definition. Expansionist might be decent if somebody would only define round. Right now nobody knows if Hygiea is a dwarf planet or not, which is the sort of thing that makes a category useless.
Nice meme – of course some categories and their justifications make more sense than others and the IAU orbital clearance one is badly flawed on that count whereas others like counting dwarf planets as planets are much more reasonable.
That list, natch isn’t comprehensive with other definitions possible like the grandfathered one or mountain vs hill arbitrary point one or Star Trek one which is that – like art – you know it when you see it! Or geologically that a body has become internally differentiated by its own gravity & / or has active geological processes eg vulcanism, mountain-building, etc.. occurring on it. Both those would of course include Pluto. Personally, my definition would be that a planet is an astronomical body that :
(1) Has never been self-luminous from core nuclear fusion thus NOT a star.
(2) Gravitationally self-rounded own gravity so NOT a comet or asteroid.
(3) Not directly orbiting another planet thus NOT a moon.
Pluto ofc passes all these criteria.
That 3 part not an asteroid / comet, moon or star definition is also simple, effective and avoids the many logical, semantic and scientific issues that the overly complex, question raising and needless IAU definition has in its highly problematic & dubious “orbital clearance” criterion. (OCC.) The clear orbit criteria is just unscientific nonsense because it results in absurd consequences like Earth or even Jupiter as well as Pluto not being a planet if its orbit isn’t “clear” – raising the superfluous question of what does “clear” even mean in that context and that renders Earth a non- planet if it finds itself on a collision course with another planet say, Mercury* or Theia** or if Earth’s orbit is further out in our solar system meaning it hasn’t got sufficient time or gravity to clear that wider path whereas it does in our inner solar system. It means a planet is defined NOT be its actual properties but rather by what is around or near it or where it ‘s located which is as silly as a defining a person by who is near them and saying that you don’t count as a human if you have a lot of similar people around you or if you are about to collide with someone!
The IAU definition also absurdly and unscientifically states that a planet has to orbit our Sun to count thus making all exoplanets non-planets and violating the Copernican principle as well! ( https://en.wikipedia.org/wiki/Copernican_principle )
Yes, to an extent most definitions and categories are going to be arbitrary and somewhat subjective but some definitions are more reasonable, logical, useful and generally better than others and the IAU one fails on those counts.
As certain predictions for our planet’s future have it – see :
https://www.space.com/6824-long-shot-planet-hit-earth-distant-future.html
** As happened in our planet’s past giving us our Moon – see :
https://en.wikipedia.org/wiki/Theia_(planet)
@18. monad :
Actually no. Titan and Ganymede are both larger than Mercury – and we also its quite possible that we may find worlds larger than many of the planets like Mercury and even Earth in the trans-Neptunian region.
Right now, Hygiea ( https://en.wikipedia.org/wiki/10_Hygiea ) isn’t classified as a dwarf planet although that might change. It wouldn’t be an issue ofc if dwarf planets counted as planets just as giant planets do. makes a lot of sense to say that as with dwarf stars dwarf planets are planets and our solar system contains gas giants eg Jupiter, ice giants eg Neptune, rock dwarfs eg Earth and ice dwarfs eg Pluto. Hence we have the gassy, the rocky and the icy as planet types. The dwarf bit being a modifier indicating the relative size of a planet rather than disqualifying something from being a planet. Of course, by analogy saying dwarf stars aren’t also stars would make virtually all of the stars including our Sun non-stars reveals how silly the IAU definition is.
Aawww, StevoR.
“The IAU definition also absurdly and unscientifically states that [blah]”
Your judgement upon the absurd and unscientific International Astronomical Union is duly noted.
After all, “Its mission is to promote and safeguard the science of astronomy in all its aspects, including research, communication, education and development, through international cooperation. Its individual Members — structured into Divisions, Commissions, and Working Groups — are professional astronomers from all over the world, at the Ph.D. level and beyond, who are active in professional research, education and outreach in astronomy.”
Your mission is the very same, right?
(Oh, my! An appeal to authority! :)
PS. For the marine biologist defintion “that only the objects that have oceans are planets” Pluto should be counted and coloured in green too given that it is thought to have a sub-surface ocean as well. See :
https://www.space.com/pluto-ocean-thickness-new-horizons
@1. Silentbob : Yeah, this is an issue that I really care about and think I have some things worth saying. Yes, I’m allowed to have and express my views and, yes, I’ve done so before and probly will again.
All I’m saying is that Pluto can be considered an honorary planet. It doesn’t deserve to get kicked out of the club for reasons.
StevoR, I hear Robert F Kennedy Jr also has opinions that are worth saying, about Fluoride, vaccines and raw milk… to the effect that the actual scientists are unscientific and absurd.
You do get that, no?
(Remind you of anyone?)
@ ^ & 21 John Morales : Totally different cases are totally different cases.
By you there, yes.
I note that you “duly noted” my views whilst truncating my words to remove why I think as I do here notably the logical issues with the Orbital Clearance part of the IAU definition. Also that you failed to say whether you agree or disagree with the points I’ve made in #19 and elsewhere e.g. recently on this thread :
https://proxy.freethought.online/pharyngula/2024/12/28/i-like-this-neil-degrass-tyson-fellow/comment-page-1/#comment-2249359
@ 16. Rob Grigjanis :
Um, you mean for classifying whether something counts as a star or not or am I misreading that? Because, no, stars aren’t disqualified from being stars based on their orbits or whether they form with or are surrounded by other stars. The orbits of stars are NOT used anywhere in determining what is and isn’t a star. Nor should they be and same applies for planets.
The only case I think the orbit matters when deciding is something is a planet or not is whether it directly goes around another larger planet and thus is a moon because that does have significant effects and I think matters more. I’m happy to count binary planets e.g. Pluto as planets but I think an object that is orbits another and is clearly a moon, is, well, a moon. Having an orbit that’s clear or not – &, again, needlessly raising the question of how then is the term “clear” to be defined” – should NOT be a determinative factor here. After all, if our planet’s orbit wasn’t clear – or Jupiter’s or Mar’es etc .. would it then no longer be a planet? Does that pass the proverbial pub test?
@9. Birgerjohansson : “Give me Von Neumann machines to process the dwarf planets and I will give a damn. Or throw the dwarf planets at Mars to add volatile substances.”
Or throw Mars at the dwarf planets – Ceres and perhaps some other larger asteroids like Pallas, Vesta and Hygiea aside – and it’ll stop being a planet because at their distance it couldn’t clear its orbit anymore either! Or Pluto where Mars is and it would be a planet. Ditto if other planets weren’t orbiting our daytime star too thus giving it that literal clear space too!
A definition that disqualifies planets because other planets are also present seems pretty stuffed to me!
Stelllar system; e.g. the Solar system. A star plus the bodies orbiting it.
Keep the dream alive, Stevo.
StevoR, you’re wasting your time.
“I note that you “duly noted” my views whilst truncating my words to remove why I think as I do here notably the logical issues with the Orbital Clearance part of the IAU definition.”
I truncated because I was not about to quote the fucking entire comment.
The relevant bit was that you dissed the premier international astronomical body and claimed they were absurd and unscientific.
You literally stated that “The IAU definition also absurdly and unscientifically states [what it states]”.
Your reasons for that are absolutely irrelevant, I was addressing your conclusion.
How that differs from RFK Jr stating that public health bodies are wrong is left as an exercise.
Anyway. In both cases, a layperson vs. reputable scientific institutions.
“Also that you failed to say whether you agree or disagree with the points I’ve made in #19 and elsewhere e.g. recently on this thread”
A planet is a planet no matter what one calls it, and so is a non-planet.
You’re hung up on terms, instead of concepts.
Pluto is the very same whether or not you reckon it’s a planet, right?
Your points don’t change any of that.
Thing is, when it comes to defining planets, I’ll take the conclusions premier international scientific body over yours. That is not the issue!
The issue is you asserting you know better than they do. That they are unscientific.
Just like RFK Jr.
@ ^ John Morales : That the IAU is the “premier international scientific body” doesn’t make them perfect or mean they can’t be wrong and a lot of astronomers disagree with them on this issue.
That the IAU definition is absurd and unscientific for the reasons I’ve already stated including violating the Copernican principle and Occam’s razor and being needlessly complicated raising more questions eg defining a clear orbit (which actually no planet in our solar system has!) – well that’s my view for all the reasons I’ve already given and I stand by that. It is to their discredit not mine. Hopefully the IAU will one day – ideally sooner rather than later – revisit their Planet definition and remedy it correcting it to one that makes a lot more logical and scientific sense like the one I suggested in #19.
StevoR, repeating yourself is futile.
I get it’s your opinion.
I get you have every right to express it.
But my point remains.
That you personally imagine the IAU has made an absurd and unscientific determination holds no more weight with me than RFK Jr’s anti-vaccine, anti-fluoridation, etc. opinions.
Are they or are they not ?
See, words mean things.
Specifically, the IAU can’t both be “premier international scientific body” and simultaneously unscientific.
(It’s a contradiction in terms; that is, an incoherent claim)
—
In your own opinion, obs.
Toldja. X-D
(@1)
(And Morales thinks I don’t understand Stevo. Foolish boy. X-D)
I am willing to “grandfather” Pluto into a planet status, if only to put an end to the complaints.
Relax, StevoR.
https://en.wikipedia.org/wiki/Essentially_contested_concept
Whether Pluto is a planet or not affects me not one bit. I won’t lose any sleep over it. What RFK Jr says pertaining to matters of public health does concern me and has serious ramifications. Dragging him into the conversation here is off-putting and a shaming move. Stick with what makes Pluto not a planet.
@30-31. Silentbob : Have you answered my question over whether you are willing to leave John Morales alone or not yet?
Hemidactylus: “Dragging him into the conversation here is off-putting and a shaming move. Stick with what makes Pluto not a planet.”
Categories; defying the scientific consensus based on personal beliefs, appealing to the few dissenters.
The modus, not the effect. The very same.
(That’s the comparison; both have reasons to think they know better than the actual experts)
Also, trying to get through via what (back in Usenet days) was called the 2 by 4.
“Stick with what makes Pluto not a planet.”
cf. my #33.
Basically, that depends on how one defines ‘a planet’.
That many thousands of the top astronomers decided that definition excludes Pluto may grate, but why would bother to change the status quo unless it helped their scientific goals?
—
In passing, did you notice how StevoR kinda exemplifies the very topic at hand? :)
(The one xkcd finds rather droll, and which PZ featured)
@36
PZ asked “You know, categories are arbitrary, subjective, and human constructed, right?”
I would highlight your alleged appeal to authority was actually to experts in the field (IAU). Not the same as asking Linus Pauling about health benefits of ascorbic acid or using Luc Montagnier as a reference for homeopathy. Experts could be wrong I suppose, but that’s not going to be decided within a blog comments section.
In trying to Hacksaw Jim Duggan Stevo with the RFK Jr sized piece of wood, I don’t know that would be the best approach in getting through to him. It rubbed me the wrong way.
“It rubbed me the wrong way.”
Consider, perhaps, that StevoR’s claim rubbed me the wrong way.
Not so much the hubris, but the cluelessness.
A bit more from my link @21:
“The IAU also has Junior Members. The IAU has a total membership of 13111. The Individual and Junior Members Directory contains 12749 names in 92 countries worldwide. These Members are labeled as “active” in the IAU database meaning they have a valid email (are able to vote and stay connected to the IAU activities) and are affiliated to at least one Division. IAU membership spans 92 countries. Out of those countries, 87 are National Members. In addition, the IAU collaborates with various scientific organizations all over the world.”
—
In passing, did you notice how StevoR kinda exemplifies the very topic at hand? :)
(The one xkcd finds rather droll, and which PZ featured)
@38
Given the array of categories in the comic, doesn’t just about everyone fit in somewhere or exemplify the topic?
You could have gone at Stevo without making that comparison to RFK Jr IMO. I might even think you are making otherwise good points mostly, but that’s kinda the nuclear option given recent events in Texas.
Reginald Selfirk@3,
A straw man is a man.
A rubber spider is a spider.
A faulty proof is a proof.
Another take on the ‘planet’ thing.
A good first approximation to the dynamics of the solar system is just the Sun plus Jupiter. Second approximation: add Saturn. Third approximation: add Venus, Earth, Uranus and Neptune. Fourth: Mercury, Mars. The dynamic effects of Pluto, Ceres and Eris are orders of magnitude less.
And in these four successive approximations, the fact that the relevant bodies have (almost, Stevo!) cleared their neighbourhood is important; it means the other bodies in a planet’s orbital zone don’t significantly affect its motion. For example, the least cleared n’b’hood of the 8 is that of Mars, which ‘only’ accounts for 99.98% of the mass in its orbital zone. Luckily for us, Earth accounts for 99.9999% of the mass in its zone. Ceres, on the other hand, sits at 25%, and Pluto at about 7%.
I think the difference of opinion (and it is only that, not a ‘right’ versus ‘wrong’) is largely down to the more physics-minded (read ‘dynamics-minded’) astrophysicists and some planetologists/astronomers.
@ ^ Rob Grigjanis : That’s true but I don’t think it should be consdiered relevant or a defining attribute of planets for the reasosn outlined in # 19 here and many times before. Its also either not true of or inapplicatble to many exoplanets that I think are obvs still planets.
@36. John Morales : “That many thousands of the top astronomers decided that definition excludes Pluto may grate, but why would bother to change the status quo unless it helped their scientific goals?”
The goal of the IAU definition was to exclude Pluto and theother ice dwarsf from counting as planets because they feared it would add too many planets to our solar system – not a goodf or valid scientific motiviation in my view.
It also ost definitley was NOT mad e by thousands of IAU members no decidced on by the entire IAU :
Souyrce : https://en.wikipedia.org/wiki/IAU_definition_of_planet#Plenary_session_debate
@ Rob Grigjanis : One other key thing to note there is that the size of the planets “neighbourhood” depends on where it is – Mercury having a shorter orbit closer in to our Sun has much less “neighbourhood” to clear versus say Pluto or Sedna in the distant reaches of our solar system – then there’s the question of how you’d define the neighbourhood of a rogue planet and how much of that neighbourhood needs to be clear.
The whole orbital clearance thing just automatically creates more questions about how you then define & determine what a “clear” orbit is and what a neighbourhood is and do that in a reasonable way -and that applies over astronomical time scales as well as over what area of space you have too. It’s a needless complication and overly subjective and thus unscientific. Science aims at more elegant, simple and brief and universally applicable as a rule of thumb yeah? The IAU definition fails there on those counts and more.
As for comparisons with the actively harmful land clearly evidence & science rejecting anti-vaxxers and RFK Jr, well, that’s beneath contempt really.
PS. Apologies for typos in #42 – meant to put that through word and thus spellcheck but pressed submit too early & didn’t. Guess it all makes sense and doesn’t need to have a fixed version repeat here? Wish we could edit comments. Sigh.
Ah, StevoR. If anyone should get it, it should have been you. Alas!
So, it wasn’t about science, in your estimation. Rather, it was about excusing exclusion.
You reckon you have their motivation at hand, but whyever would they have that goal, the one you (in your mastery of astronomy) assert is unscientific?
They get to have their say. Like, you know, eligible voters.
But fine, you reckon most professional and active PhDs and above couldn’t be fucked voting on such a thing. It was but an artefact of timing, you intimate. Not a real vote, not a real consensus.
From your very own link:
I get it. You reckon it’s unscientific because not enough members voted; it was a fly-by-night usurpation or science. Back in 2006, but hey. Actual scientific astronomers haven’t had a chance to fix the fix, yet.
(Seriously!)
—
You know how there’s been a thematic continuum of posts about the denigration of science?
(You exemplify that it’s not just on the right or the fascists — but, of course, such denialism is part and parcel of applied ideology)
StevoR: Yes, only about 400 took part in the IAU vote. But that’s large enough that it should, at least roughly, statistically reflect the views of all IAU members. Unless you think that, either by sheer coincidence, or some sort of skullduggery, the possible ‘noes’ were vastly underrepresented?
Anyway, the vote was so overwhelmingly in favour of the new definition that they didn’t bother counting. Perhaps you see something nefarious in that too?
In the twentyish years since then, the opposition has been rather underwhelming. The largest petition I’ve seen had a few hundred signatories, and you didn’t need any qualifications to sign (I know, because I signed it just to check).
You clearly think you know better than the vast majority of astronomers, who are at least OK with the definition. But I haven’t seen much actual understanding of what it even means in your posts. They’re just nitpicking about semantics, or ridiculous hypotheticals.
Here’s some light reading for you:
https://arxiv.org/abs/astro-ph/0608359
PS Rogue planets don’t have ‘neighbourhoods’ (aka ‘orbital zones’) because they don’t orbit anything.
For nitpickers: “they don’t orbit anything” should be “they don’t orbit any star”.
@ ^ Rob Grigjanis : So what does that make their “neighbourhoods” (defined how?) and their “clear orbits” are what and cover how far? (Defined how again?) Yet they clearly are planets still. Aren’t they? Why not, if not? If not then what are they exactly?
If that happened to Earth or Jupiter, they’d still be planets yeah?
So what does that say about the IAU definition and how and where it fails again? What does that imply to you?
StevoR, clickety-click is your friend. https://www.iau.org/static/archives/releases/doc/iau0603.doc
@45. Rob Grigjanis :
I don’t know but maybe? That was one moment, one snapshot that, yeah, I’m certainly not sure was representative of the astronomical community in the heat of that particular moment and those particular circumstances. Even if it was representative then the question is was it the right decision?
I’d say, pretty obvs not.
So, when we have a decision that’s pretty obvs wrong what do we then do about it? I’d say it needs to be fixed and changed so the IAU gets a better more reasonable definition that rejects the whole “clear orbit” criterion. Already suggested my proposed replacement in #19 here.
Are they tho’? Really?
Even if they are – does that mean they are right or merely that most astronomers don’t care enough about what is clearly a flawed definition?
What exactly is “ridiculous” about the hypotheticals I’ve posed here?
The whole issue here is about semantics by (literal) definition but yeah. Its nit picking to say that something is a planet or not? That a dwarf of whatever category is a dwarf but also still belongs to that category.
If a dwarf star is a dwarf star. if a dwarf person is a dwarf person, well, consistency?
@ ^ Notice I’ve already cited cases in #19 where the hypotheticals either have or are quite possibly going to occur in real life.
@48. John Morales : I’m seeing a lot of gibberish and, I’m guessing, coding symbol thingies there. Might’ve opened in wrong thing and a bit of clarifying exactly what I’m supposed to be seeing would be good.
But it seems to be the IAU Planet definition Resolution which, yeah, I know about already and strongly disagree with..So relevance? Purpose? Actual argument addressing what I’ve been saying here?
@45. Rob Grigjanis : “Here’s some light reading for you:”
Link goe sto abstract :
Okay, thanks. That’s Steven Soter’s personal planet definitoon which I note differs from the IAU one and dispenses with upper and lower mass limits.
Its not a definition I think makes sense given the need for some lower and upper limits – as noted already mine would be upper limit = capable of luminosity from core nuclear fusion = brown dwarf and lower limit = capable of being gravitationally rounded by own gravity
It also means that rogue planets that are superjovians that form from fragmenting gas disks and nebulae directly aren’t planets which, okay, why wouldn’t they be?
I prefer my definition from #19 still for those reasons. Do you think Soter’s definition is preferable then and if so why?
StevoR: FFS, if you actually read Soter’s paper, your ‘objections’ would be answered. On this topic, at least, you come across like a fundamentalist. You start with your belief, and attack anything differing as ‘unscientific’ without actually understanding the science. Then you come back, time after time, with the same ‘arguments’. The kicker is that you think you’re ‘obvs’* right.
PS Pet peeve; is it really that hard to write ‘obviously’? Is this an Aussie thing?
@ ^ Rob Grigjanis: Colloqiuial slang, yeah. We tend to dilike exewcessively long words here and why is abbriebviation sucha long word?
FYI. Its well after midnight here now and i’ve goty work tomorow and other stuff on. I will read Soter’s paper properly when I have time. For now, going off the abstract link as noted.
PPS. Americans should understand, I mean ask any Brit how “Al-you-mini-um” should be pronounce-ed.. ;-)