back to article YOU! DEGRASSE! It's time to make Pluto a proper planet again, says NASA boffin

Those who feel that Pluto has always been a planet and jolly well ought to be one again have received a boost - this time from a top NASA boffin, albeit a slightly biased one. "It's very hard not to call an object with this level of complexity in its geology, and such complex seasons, a planet," said Alan Stern, New Horizons' …

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  1. John Savard

    Wishing and Hoping

    For sentimental reasons, I would very much like Pluto to be a planet, pure and simple, once again. However, that would mean that Eris would have to join it as a new planet in our Solar System.

    And that's the problem, because there could be many other planets in the Kuiper Belt of comparable size. For a while, Ceres, Pallas, Juno, and Vesta were accepted as planets - but then it was clear this would be untenable, as the extent of the asteroid belt began to emerge. It appears that the same thing has repeated itself when it comes to KBOs.

    Whether or not we like it, I think the IAU's decision makes sense and was the only one possible.

    1. JeffyPoooh
      Pint

      QotY

      "If Neptune had 'cleared' its orbital zone, then Pluto wouldn't be there."

      .: The IAU are idiots.

      ...

      Note. I don't really care if Pluto is a planet or a dwarf planet. But it's important that bogus logic be ridiculed at every opportunity. The IAU bungled this one, and deserve no mercy.

    2. skerns0301

      Re: Wishing and Hoping

      The fact that Pluto has a techtonily active crust (Mercury and Mars don't) should rank Pluto above them on the planet list--the simple fact is Mark Brown was grasping at what ever straws he could find to gain his " Andy Warhol" fifteen minutes of fame-- the Earth at Pluto's distance would not have "cleared it's orbit"--Jupiter hasn't-- and with five moons and a tectonically active crust Pluto is most certainly a planet

      Stan

      1. h4rm0ny

        Re: Wishing and Hoping

        And honestly, why shouldn't it be a planet. Planet isn't a term that has any precise scientific meaning? No space probes will crash because they expected 2 Planets worth of gravitational force to affect them and there was only 0.5 Planets of gravitational force. It's not a scientific term, it's a cultural one. You want to correct someone who calls a hyena a canine because it's not? Fine - there are precise meanings behind the term. But there's nothing that says "planet = Xkg in mass".

        It's been a planet for most of its existence and it's really just a cadre of people who like correcting others that took it up as a crusade. Call it a planet, no-one will get confused. In fact, confusion and arguments will drop. And I say all this as someone who back in the day argued fiercely against metric KB and KiB inventions - they affected me as an engineer. But what the Hell is the scientific definition of "planet". It's just a layperson's term so let 'em have it.

        1. Shonko Kid
          Mushroom

          "Call it a planet .... and arguments will drop."

          Perhaps that's the point. I thnk every sufficiently large community needs it's own 'flame war' talking point, and this is just theirs, giving them something to argue about at conferences, write papers and books on, and keeping them on the talk-show circuit for life!

        2. mhenriday
          Boffin

          Re: Wishing and Hoping

          «It's been a planet for most of its existence ...» Really ? For most of its existence - do you mean since it was detected from Earth by Clyde Tombaugh in 1930 and given the name Pluto later that year after a suggestion by an English schoolgirl ?...

          I suspect that this body has been around much longer than the 85 years since it was first classified as a «planet» and that the definition of the term is subject to change, as our knowledge of the star system in which we live increases....

          Henri

      2. Dagg Silver badge
        FAIL

        Re: Wishing and Hoping

        >The fact that Pluto has a techtonily active crust (Mercury and Mars don't) should rank Pluto above them on the planet list

        No, there are moons Europa and Titan that have tectonically active crusts that are bigger than pluto.

    3. Vatnos

      Re: Wishing and Hoping

      I think the "dwarf planet" category makes good sense, but I think they applied the term the wrong way. Dwarf planets should be seen as planets the same way giant planets and terrestrial planets are seen as planets. It's just another way that a planet can be. So what if there end up being 30 of them? The universe doesn't care about whether dumb schoolkids can memorize names.

      I don't have any particular emotional investment in Pluto's planethood. I dislike the IAU's definition for other reasons. Partly, I think the decision was made when it was thought a lot more objects like Pluto would be found in the Kuiper Belt, but so far we've only found 1. The rest are a good bit smaller, and there's only a 1 in 3 chance of finding any more. The other reason is that it seemed like the decision was based on anthropocentric thinking rather than scientific thinking: "keeping the numbers low and human-sized" rather than describing objects based on... what they living are.

      -------------------------

      Instead of the IAU definition I think there should actually be two new categories instead of one:

      Dwarf planets - which should be Planets with a capital P - things like Pluto and Eris, that are large enough to be geologically active and dynamic, but are small and composed of ice, and located in a belt with other similar objects.

      Protoplanets - basically everything else below 2000 km but above 800 km in size. These objects (like Ceres) are large enough to form a sphere but small enough that they remain inert their whole lives. These would be considered a step up from comets or asteroids but they would be a rung below planets or even dwarf planets. Things like Ceres, Varuna, Quaoar would fit right in here nicely.

      I think this line of 'potential geological activity' makes more sense than the arbitrary orbital requirement--which doesn't even rule out Ceres from being a planet technically, as nothing else in its orbit is remotely close in size. Yet if we found something the size of Mars in the Kuiper Belt or the Oort Cloud (very possible), we'd have to consider that a dwarf planet due to this definition.

      1. BillG
        Megaphone

        Re: Wishing and Hoping

        The IAU does not include a single planetary scientist and made a non-scientific decision with only a partial membership there to vote.

        Astronomy inspires and motivates us. I spent my youth looking at the stars. As a degreed scientist, I choose to not recognize the IAU's decision.

      2. Anonymous Coward
        Anonymous Coward

        Re: Wishing and Hoping

        I dont think "protoplanet" would be a good term for the Ceres-like objects. The "proto" part in todays language implies it was in the process of becoming a planet when it halted for some reason. Like a prototype.

        From what we now know of Pluto, once the atmosphere and ice has ablated in however many million of years it is very likely to be just a geologically inactive round ball much like Ceres. So just like a bunch of asteroids can apparently clump together into a planet, so can a dwarf Planet erode away into a ... whatever.

    4. John Brown (no body) Silver badge
      Alien

      Re: Wishing and Hoping

      "there could be many other planets in the Kuiper Belt of comparable size"

      Asteroid Belt 2.0? (Currently in beta test)

  2. Your alien overlord - fear me

    IAU voters were in the main, astronomers who deal with galaxies and the like, planetery scientists should be the ones to decide if something is a planet.

    It's like having road builders decide a BMW is not a car because it is't made of tarmac.

    Yes downvoters, that is how rediculous the dsciption and subsequent vote was.

    Where's my I love Pluto icon?

  3. Anonymous Coward
    Anonymous Coward

    The Sun and Moon ...

    ... were once considered planets - see Dante's Paradiso.

  4. iLuddite

    more than a planet

    Active geology, atmosphere, seasons and several orbiting moons may qualify it as a planetary system, not just a planet. Sometimes size does not matter.

  5. ZSn

    American

    You forgot one vital thing - it was the only 'planet' found by an American. The most vocal critics of this decision are found in the USA. Chauvinism is alive and well in science the same as any other human endeavour.

    The seasons and activity argument is frankly ridiculous, titan is bigger and also has weather - ideas it a planet as well?

    1. Captain DaFt

      Re: American

      "titan is bigger and also has weather - ideas it a planet as well?"

      If Saturn ignites and becomes a sun, yes. Until then it's just a moon.

      1. asdf
        Mushroom

        Re: American

        >If Saturn ignites and becomes a sun

        Too bad it's Jupiter that has the Monoliths. For the record not all Americans are slaves to nationalism. Pluto is not even close to the most interesting TNO in this American's opinion (Sedna on the other hand and not because it was discovered by another American either).

      2. ZSn

        Re: American

        And Ceres is spherical - that still doesn't make Pluto a planet

        1. Roq D. Kasba

          Re: American

          Two American states have passed legislature stating that it is a planet. Famously, didn't one US state pass similar legislature that π=4 at some point? Doesn't really bolster the case.

          That said, I'm in team planet, because why the hell not.

          1. Graham Dawson Silver badge

            Re: American

            No, it didn't. You're thinking of the failed Indiana Pi Bill, a legislative attempt to square the circle - something politicians and legislatures around the world have been attempting to do in one form or another ever since they were invented. It was just rather more literal in this case.

          2. h4rm0ny

            Re: American

            I upvoted you just for "Team Planet". Beats the Hell out of "Team Downgrade Classification".

    2. h4rm0ny

      Re: American

      British support of Pluto's Planethood right here. Don't be so xenophobic. At best, I think you're just suffering confirmation bias from the fact that this is more of a controversy in the USA. In most of Europe and Asia, most people still just think of it as a planet so of course you'll see less argument.

      I don't care if an American discovered it. I don't discount Venus because a bunch of Sumarians or Mayans first documented it.

    3. John Brown (no body) Silver badge
      Joke

      Re: American

      "You forgot one vital thing - it was the only 'planet' found by an American. The most vocal critics of this decision are found in the USA."

      ...and should have the least say since their country (the state, not the geographical place) hasn't even been in existence for a full Plutonion year yet!

      1. Anonymous Coward
        Anonymous Coward

        Re: American

        > Here in the US both New Mexico and Illinois have passed legislation that has explicitly defined Pluto as a planet.

        Typical American arrogance. Whether you agree with the classification or. not, you can't go making laws about it.

        Have they made laws on whether global warming exists yet? Or if God is real. etc.

        Anyway, if they really have that much free time, maybe their numbers should be culled, or they could be working on ways to make it even easier for cops to murder black people, or maniacs to get guns

        1. Anonymous Coward
          Anonymous Coward

          Re: American

          Mummy give baby too much sugar?

  6. Anonymous Coward
    Anonymous Coward

    The Designation of needs to be down graded

    The revelations of the the surface and materials of the Kuiper Belt Object shows that it is only a larger version of those objects that visit the inner Solar System with hopefully a stable orbit.

    The new designation should be C2015-New Horizon - that is a COMET

    1. Allan George Dyer

      Re: The Designation of needs to be down graded

      Upvoted, not because I agree, but for your chutzpah. If you start a trend, we might be re-designating Mercury as a failed comet.

  7. Jordan Davenport

    IANAA, but...

    The classification of "dwarf planet" doesn't mean the thing isn't interesting or doesn't deserve studying. Mass, volume, and composition aside, my biggest remaining objection to considering Pluto a fully fledged "planet" is actually part of what makes it interesting - its orbit. The eight planets all orbit within a few degrees of the same invariable plane. Pluto on the other hand orbits at a fairly steep inclination compared to the other planets.

    Why is this? What can Pluto and the other Kuiper belt objects tell us about the formation of the Solar System? Could we maybe have at one point had a sibling star or two that have since drifted away? Could interstellar space be a little less empty than we thought?

    By all means, study Pluto. Don't take a diminutive reclassification as an affront to your research, and most importantly, don't think that only something as grandiose as a planet or star deserves study. Just don't claim it deserves to be in the same rank as the terrestrials or gas giants because it's not just a boring ball of rock and ice orbiting the sun.

    1. graeme leggett Silver badge

      Re: IANAA, but...

      could we reclassify it from a dwarf to an "eccentric planet"?

      1. I ain't Spartacus Gold badge
        Happy

        Re: IANAA, but...

        No. It can be a mad planet though. That will only change if we discover gold, platinum or diamonds there. Only once you're rich, do you qualify as eccentric...

  8. disorder
    Flame

    I rather don't explicitly care whether it is, or isn't. I just want a decision not made by 'the public'. (The moronic kind; that legislate that it's a planet, or that PI=3 (really)) Because they can't (consistently) have Pluto and not Eris. And Quaoar. And several others they won't be able to pronounce with any more credulity, than when they ask to see pictures of Uranus.

    This was, more or less the reason for the (contrived) definition that IAU got, and in fact I think it's fine; that it means 'planet' tells you something about the /solar system/ because of the implied orbital dynamics (Kuiper Belt - is not the same region as where a few trojans are hanging around - neptune shaped it). Not just that it's a ball of whatever (or literally, just a ball). Whether or not that definition makes sense for any other solar system (and IAU already said it doesn't), being something else entirely.

    Pluto is clearly a world more fascinating than we could have hoped for (and Triton set a few expectations has Pluto roundly beat). And there's more than just it out there, that is even within our reach.

    I don't think the classification degrades it (many seem to). I think it's solveable, as a matter of emphasis.

    'The public' let's be realistic after all has no appreciation of what these bodies are, or if they do, it's as those nice pictures that are all more or less the uniformly biggest sphere that could fit on the page, or from bad (or less bad) TV sci fi shot in studios at 1G.

    But (as I'm sure many here actually know) ref: http://scienceblogs.com/startswithabang/files/2013/11/Solid-Solar-System-Planets-Compared.png - they are - severely - not the same size. At all.

    What is _your_ minimum cut off going to be? Every grain of dust?

    There are arguably only two 'major' terrestrial planets in the solar system, based on what it'd mean to us to try to run on it (rather than hop) without faceplanting. I'm not saying that's what I'd pick. But in PR terms there'd then be 7 rocky planets - two major ones. and 4 giants (2 gas, 2 ice) and you can call that 11 if you want, and a lot of dwarves.

    Sooner or later each press place with only humanities grads trying to figure it out will use a different number, and people (americans) will stop caring. While highlighting at the same time, that the amazing thing, is that these bodies are *nothing* alike and thus worthy of a lot more space flybys and orbiters.

    Most (all?) other astronomical classifications get away with not changing, and noone cares (see supernovae, star spectral class, etc). But WIMPS still can get on with finding their MACHOS regardless.

  9. revilo

    Nomen est omen

    The change the nomenclature was little minded. There are many things which technically should be called differently, even in mathematics. But why complicate things and change established names? Removing the planet status was silly. A tomato is considered a vegetable even so technically, it is a botanical fruit. It would be equally cranky to demote the tomato of its vegetable status. The same fanaticism is sometimes also applied to language, where spellings can be inconsistent. Does this warrant to change the vocabularies and books? Correcting them produces more problems instead of leaving it and keep a bit of culture. When developers of programming languages pull such stunts and remove inconsistencies in well established languages, they even risk to kill the language because all previously written code needs to be adapted.The fact that Pluto was considered a planet was culturally and historically grown. Instead of applying a hair splitting and cold definition, one should have taken the history into account. Science is grown, built by humans and it does not help science to be pedantic. The Pluto name change story shows however that many folks care and feel strongly about such things. And that is nice.

    1. Charles 9

      Re: Nomen est omen

      The thing is, when it comes to science, precision matters. Science MUST be pedantic or mistakes linger. Once upon a time, the Church taught that the Earth was the center of everything; everything had to change then, too, didn't it?

      That's why botanists distinctly classify the tomato as a fruit (more specifically, a berry like its cousin nightshade). Now the debate about Pluto continues with the thought of a new reason to classify: geologic activity. I mean, are there other Kuiper Belt Objects with atmospheres and active geology and so on? Is Erin geologically active, for example? Let the debate rage, I say. If textbooks have to be changed, then that's the price of progress. Is it worse to correct a big mistake than to let people live in incorrect ignorance?

      1. h4rm0ny

        Re: Nomen est omen

        >>"The thing is, when it comes to science, precision matters. Science MUST be pedantic or mistakes linger."

        Sure. But planet has next to no scientific meaning. When you're calculating the path of your spaceprobe, you factor in 1x10^6Kg mass to your slingshot calculations, not "1 planet".

        Planet is a cultural term used by laypeople.

    2. J.G.Harston Silver badge

      Re: Nomen est omen

      "Vegetable" is a culinary term, not a botanical term, so it can overlap with several botanical terms.

      1. Ian Easson

        Re: Nomen est omen

        No,

        "Vegetable" is a biological term that has been grossly misused as a culinary term.

        For example, the following are biological fruits (because they contain embedded seeds), although in common culinary terms most people mistakenly believe them to be vegetables:

        - Tomatoes

        - Eggplant

        - Cucumbers

        The reason for this misidentification is that most people associate "fruits" with things that are "sweet".

        1. Charles 9

          Re: Nomen est omen

          The same problem exists with nuts. From a culinary perspective, it's an edible seed, but from a botanical perspective, nuts are a specific kind of edible seed that grows on trees and has no outer flesh, among other qualifications. Thus you end up with culinary nuts that aren't botanical nuts, like almonds and pistachios (drupes: they have outer flesh so are really the single large "pit" of a fruit) and peanuts (legumes: it's the "pea" part that is botanically accurate) and cashews (straight seeds of a fruit, not to mention toxic in raw form).

        2. Ken Hagan Gold badge

          Re: Nomen est omen

          I think you'll find that people have been cooking for quite a lot longer than they've been classifying things in biology. So the culinary definition got there first and the biologists borrowed it *knowing* that it didn't cover exactly the same ground as they wanted, but it was close enough.

        3. Frumious Bandersnatch

          Re: Nomen est omen

          re: Is "vegetable" a culinary or biological term?

          I think you missed the point there, Ian. The OP said that "vegetable" is a culinary term and you disagreed by talking about fruit. What is this specific biological use of the word "vegetable" that you think that people are abusing? I think that, biologically speaking, "vegetable" is so broad as to be impossible to misapply. I think that, rather, your real beef is with people not knowing what a fruit is (and probably, by extension, the common fruit/veg dichotomy).

          Personally I have no problem with a word having two meanings depending on context or field. I know that things like tomatoes (and other crops from the nightshade family apart from stuff like tobacco and potatoes whose fruits are poisonous), all the squash/cucurbit family, rose hips/haws and even beans are technically fruit in the biological/horticultural sense, but I've no problem with these things being "misclassified" in the fruit or veg aisles at the supermarket. No more than I mind people saying that "the Internet is down" or similar.

          Reminds me of the saying (no idea who came up with it) that "knowledge is knowing that a tomato is a fruit; wisdom is not using it in a fruit salad."

          As it is with fruit, the same could be said for Pluto. Some experts might use a specific definition of what a planet is, but it doesn't stop the general public having their own ideas, too. Who cares if a bunch of astronomers use the word "planet" one way? The only place where the "correct" definition makes any difference would be in exams, pub quizzes and dictionaries and, frankly, none of these holds any sway over me.

    3. TheOtherHobbes

      Re: Nomen est omen

      Perhaps we should reclassify Pluto as a fruit?

      1. Paul Woodhouse

        Re: Nomen est omen

        I want to know how many swallows it would take to carry a Pluto 100km

  10. Chris Miller

    Categorisation isn't a problem that's unique to astronomy. There are countless objects within the solar system - some orbiting the sun, some orbiting each other* - and whatever human-imposed dividing line we choose, there will be objects in one class close to the boundary that have more in common with objects in the other class than those in their own.

    Pluto is simply the largest (as far as we know at the moment) 'dwarf planet' rather than the smallest 'planet', but the distinction is a purely linguistic one and makes no difference to the properties of the object itself.

    * Even this distinction isn't completely clear cut, 'Trojan' objects (at L4 or L5) can be considered as orbiting the sun or their neighbouring planet.

  11. Byz

    Categorisation is human trait

    Over the years I have worked on many systems where the client wants to categorise something.

    Generally it works for man made objects, however like all things there are exceptions (is an infrared lamp a lamp or a heater? It's technically both people don't like this)

    If you look at the planets each on is unique in some way, but we just like putting things in a box.

    If you work extensively with logic you begin to realise that categorisation is a cognitive thing rather than real. You can write the same program in procedural, object oriented, functional and protocol oriented paradigms they are all isomorphic with each outer it is just a different way of categorising a problem.

    Personally under the dwarf planet definition I would shove Mercury in there as it so close to the Sun that the Sun clears the region (it also almost cleared out Mercury as it used to be bigger, like Pluto).

    So it is just a putting it in a box exercise, driven by administration not science. Light used to be just a wave in the 19th century until the photoelectric effect was discovered and Einstein screwed it all up with the photon :)

  12. David Roberts

    Moon?

    It has been suggested that our Moon (up there in the sky) may no longer fit the formal definition of a moon, but might be a dwarf planet in a binary system with Earth.

    Given that it gave the name to the class of objects currently described as moons this does make the whole naming argument a little surreal.

    1. Ken Hagan Gold badge

      Re: Moon?

      If the Earth was less massive, the Moon would be a double planet. Same object, but the difference lies elsewhere. If Titan orbited the sun, it would be a planet. Same object, but the difference lies elsewhere. Meanwhile, Jupiter and Mercury are both planets. Vastly different objects, but the similarity lies elsewhere.

      As long as you insist on using one word to describe both the object and its position, you can't escape this nonsense, since an object and its position are only weakly correlated (by whatever rules govern the origin of solar systems).

      Personally I'm quite happy to describe Pluto, Titan and the Moon as planets when I'm concerned with their geology, moons when I'm concerned with their orbit. (Pluto is a "double moon", a satellite of both the Sun and Neptune. There's no word for it, but it *is* rather awesome, so there should be. In fact, perhaps that's what the word "Plutoid" should mean.)

      1. rfif1541

        Re: Moon?

        I don't see how Pluto could be a satellite of Neptune if it doesn't orbit it. Also because Pluto Crosses Neptune's orbital path I think we need to declassify Neptune as a planet because it hasn't cleared its path around the sun. When some say there are moons bigger then Pluto so they should be planets. NO these moons orbit a planet Pluto orbits the sun. Mercury is just a little bigger than our moon so it should be classified as a moon orbiting the sun. Ganymede is 3273 miles in diameter mercury is 3032 miles in diameter. again Mercury is a moon orbiting the sun. Mars is 4212 miles in diameter so its not a planet it is a moon that escaped Jupiter's gravity. So its just all stupid Pluto is a planet, its just a small planet. We are so privileged. This generation is the first humans to set eyes on this amazing planet. For me its special I'm over 60 yrs old and most of my life Pluto was the 9th planet. I never dreamed I'd live to see it. So let me go on believing that Pluto is a planet. I envy you young people you will probably see man set foot on Mars. Maybe see habitats with humans living and growing crops It will be an amazing time. I love space so much but was born in the wrong era.

    2. VinceH
      Alien

      Re: Moon?

      But the moon is neither - it was revealed in the Doctor Who to be an egg!

      1. Ken Hagan Gold badge

        Re: Moon?

        That episode isn't canon. A special meeting of the International Who Fanclub declared that despite airing as part of an the official series, it had failed to clear its plot of debris.

        1. VinceH

          Re: Moon?

          So it's only dwarf-canon, then?

        2. BuckeyeB

          Re: Moon?

          A lot of episodes fail to clear its plot of debris.

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