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NASA Space Earth Moon Science

NASA Scientists Propose New Definition of Planets, and Pluto Could Soon Be Back (sciencealert.com) 213

Rei writes: After several years of publicly complaining about the "bullshit" decision at the IAU redefining what comprises a planet, New Horizons program head Alan Stern and fellow planetary geologists have put forth a new definition which they seek to make official, basing planethood on hydrostatic equilibrium. Under this definition, in addition to Ceres, Pluto and other Kuiper Belt objects, large moons like Titan and Europa, as well as our own moon, would also become planets; "planet" would be a physical term, while "moon" would be an orbital term, and hence one can have a planetary moon, as well as planets that orbit other stars or no star at all (both prohibited under the current definition). The paper points out that planetary geologists already refer to such bodies as planets, citing examples such as a paper about Titan: "A planet-wide detached haze layer occurs between 300-350 km above the surface; the visible limb of the planet, where the vertical haze optical depth is 0.1, is about 220 km above the surface."
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NASA Scientists Propose New Definition of Planets, and Pluto Could Soon Be Back

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  • by Anonymous Coward on Thursday February 23, 2017 @03:07AM (#53915853)

    oh wait, it is just a moon.

    • Re:That's no moon (Score:4, Interesting)

      by quenda ( 644621 ) on Thursday February 23, 2017 @05:25AM (#53916085)

      Moons are next on the hit list.
      At last count Jupiter has 67 so-called moons: The four Galilean moons, plus 63 rocks.
      We really need to clamp down on what counts as a moon, or every bit of space-trash will demand to be listed.

      • Re:That's no moon (Score:5, Interesting)

        by mysticgoat ( 582871 ) on Thursday February 23, 2017 @06:38AM (#53916201) Homepage Journal

        Any "space-trash" that demands to be listed as something else needs to be immediately identified as a "sentient being", and on behalf of all of us Earthlings the UN needs to publicly apologize to him/her/it. That is simple playground rules: you don't want to insult anybody that much bigger than you are.

        As to everything else, I think the planetary geologists have it right. If it is big enough to be rounded of its own volition, it is a planet. And planets that go around another planet more quickly than they go around their star are also moons.

        Corollary: that makes Earth the larger part of a binary planetary system. Which puts proper emphasis on the way the Moon creates tides that keeps the hydrosphere stirred up, which has had a major impact on how life has evolved here. Exoplanetary explorers should look for other binary planets in the Goldilocks zone as these are much more likely to have life that is similar to Earth life.

        (Is a "bazinga!" called for here? Was this just another Sheldon impersonation, or did I accidentally say something insightful?)

        • by quenda ( 644621 )

          that makes Earth the larger part of a binary planetary system.

          There is a rule to avoid that. If the common centre of mass is inside one body, Earth in this case, it is considered a planet & moon, not a binary.

          • That's one of those foolish rules put forth by the idiocy contingent of the IAU.

            The barycenter of the Earth - Moon binary is outside of the Earth's hard inner core, in the region of the liquid outer core. This is the center or neutral point of the tidal forces acting on the Earth. No one has yet looked at the effects of these tides on the outer core's liquidity, or its electromagnetic properties, mostly because astronomers look upward and geologists look downward and there is a very serious failure for eit

            • Very insightful stuff. Out curiosity, what are your thoughts on formally recognizing the Sol/Jupiter binary system -- it's barycenter being outside of the Sun entirely? All of this terminology just goes so many levels deep...fun stuff haha.

              • My thinking has been too Earth-bound to consider the Sol - Jupiter relationship. But I see others are thinking about it; there are several lay articles and apparently some more serious articles on the web. But I haven't done any critical reading on the subject.

                There does seem to be a correlation between Jupiter's orbital period and the sunspot cycle as both are roughly 11 years. But if there is an underlying mechanism (not conveniently dismissible as "coincidence"), it seems more likely that the mechanisms

                • But I haven't done any critical reading on the subject.

                  There does seem to be a correlation between Jupiter's orbital period and the sunspot cycle as both are roughly 11 years. But if there is an underlying mechanism

                  I'd advise you to do your critical reading. Look at the numbers and you'll find that the range of solar sunspot cycles is from 8.8 years to 14 years ; the corresponding orbital period for Jupiter is 11.875 years - 4331 days - with a variation of a lot less than a day. Remember that Ole Roemer was

                  • As I know I mentioned before, I doubt that there is a gravitationally mediated interaction between Jupiter and the solar cycle, and if there is a electromagnetic interaction, then that would involve Saturn as well as Jupiter, and probably Earth. Both Saturn and Jupiter have a strong impact on the solar wind. During the years when they are in close heliocentric conjunction, Jupiter's magnetotail and the bow wave of Saturn's magnetosphere are trying to occupy the same space. There has got to be some interesti

                    • Well, if you want to get handwavey instead of siency, that's your choice. It doesn't strengthen your arguments in the slightest.

                      Without getting into essential complexities (e.g., the orbits are not circular, but elliptical), there's one very simple check that you don't seem to have considered. The 1.3 difference in orbital inclination between Earth and Jupiter means that the projection of the Earth's magnetotail out to Jupiter's orbit will be up to 23 million km (nearly 1/4 AU) above or below the line of

                    • When did bloody Slashdot's atrocious entity-handling stop being able to present the degree symbol, "& deg ;" (without, of curse, the spaces)?
                    • You don't bother to look up anything you've never been taught, I guess.

                      The magnetospheres of the planets that have them are several times the radius of the physical planet. But even greater than that, the field effects of standing waves and turbulence in the solar wind extend well beyond the magnetospheres that shape them. Remember (or look it up since it seems like you've never been taught about it) that the solar wind is composed of mono-atomic ions and free electrons moving at very high speeds. What lie

                    • "Mystic" and "goat" in the same user name should probably have been a good warning.

                      Anyway, for the silent audience, I did a couple of other calculations last night. (Something you seem remarkably resistant too. Whether that's the "mystic" part of your chosen persona, or the "goat", I neither know nor care.) Given the respective diameters of the Sun and the Earth, and their spacing, it is a simple matter to calculate that the optical tail, the umbral shadow, of the Earth is around a million km long. How lon

  • by Anonymous Coward

    As far a I am concerned, it never went away.

    • No, that's wrong. Nothing can be considered a planet if it is smaller than Neil DeGrasee Glactus' ego. Dwarf planets are no more real planets than dwarf people are real people.
  • Maybe (Score:5, Funny)

    by sexconker ( 1179573 ) on Thursday February 23, 2017 @03:29AM (#53915889)

    Maybe stop changing arbitrary definitions. Pluto was always a planet. Fuck you, NASA and shitty celebrity "scientists" like Neil Tyson.

    • Re: (Score:1, Insightful)

      by Anonymous Coward

      Maybe stop changing arbitrary definitions.

      Definitions like this will be arbitrary, and it just comes down to what makes it easier to write journal articles (where IAU has any authority). If Pluto was included in planets, there are quite a few orbital dynamics and evolution papers that would need to use the phrase, "The planets excluding Pluto....". There are plenty of papers on geology and atmospheric dynamics that wouldn't care about the orbit and would benefit from a definition like proposed here. There are others that would need to take a def

      • Re:Maybe (Score:5, Interesting)

        by Rei ( 128717 ) on Thursday February 23, 2017 @06:03AM (#53916121) Homepage

        Clearly given that people like Stern have regularly given interviews decrying the decision, and going so far as to call it "bullshit" (can you say that at NASA?), it's clearly not the storm in a teacup that you want to present it as.

        What the proponents did was take a term widely used by planetary geologists and have it mean something completely different - akin to dentists suddenly declaring to doctors that the heart is no longer an organ and to stop referring to it as one. And contrary to your presentation of why they did it ("to make it easier to write journal articles") without fail every last supporter I've seen interviewed about their vote has given some variant of the following reason for why they voted the way they did: "I don't want my daughter having to memorize the names of hundreds of planets." Which is so blatantly unscientific it's embarrassing that such a thing would influence their decision at all on a scientific matter.

        The IAU vote was narrow, at a conference only attended at all by a fraction of its membership, on the last day when a lot of the people opposed to the definition they passed had already left because it had looked up to that point like there was either not going to be a vote at all , or one on a hydrostatic equilibrium definition - all options that they were fine with. Only 10% of the people who attended were still around.

        I have a lot of issues with the last vote, and that's just the start. Here's my full list:

        1. Nomenclature: An "adjective-noun" should always be a subset of "noun". A "dwarf planet" should be no less seen as a type of planet than a "dwarf star" is seen as a type of star by the IAU.

        2. Erroneous foundation: Current research agrees that most planets did not clear their own neighborhoods, and even that their neighborhoods may not always have been where they are. Jupiter, and Saturn to a lesser extent, have cleared most neighborhoods. Mars has 1/300th the Stern-Levison parameter as Neptune, and Neptune has multiple bodies a couple percent of Mars's mass (possibly even larger, we've only detected an estimated 1% of large KBOs) in its "neighborhood". Mars's neighborhood would in no way would be clear if Jupiter did not exist - even Earth's might not be. Should we demote the terrestrial planets as well?

        Note that the Stern-Levison parameter does not go against this, as it's built around the ability of a planet to scatter a mass distribution similar to our current asteroid belt, not large protoplanets.

        3. Comparative inconsistency: Earth is far more like Ceres and Pluto than it is like Jupiter, yet these very dissimilar groups - gas giants and terrestrial planets - are lumped together as "planets" while dwarfs are excluded.

        4. Poor choice of dividing line: While defining objects inherently requires drawing lines between groups, the chosen line has been poorly selected. Achieving a rough hydrostatic equilibrium is a very meaningful dividing line - it means differentiation, mineralization processes, alteration of primordial materials, and so forth. It's also often associated with internal heat and, increasingly as we're realizing, a common association with subsurface fluids. In short, a body in a category of "not having achieved hydrostatic equilibrium" describes a body which one would study to learn about the origins of our solar system, while a body in a category of "having achieved hydrostatic equilibrium" describes a body one would study, for example, to learn more about tectonics, geochemistry, (potentially) biology, etc. By contrast, a dividing line of "clearing its neighborhood" - which doesn't even meet standard #2 - says little about the body itself.

        5. Mutability: Under the IA definition, what an object is declared as can be altered without any of the properties of the object changing simply by its "neighborhood" changing in any of countless ways.

        6. Situational inconsistency: (Related) An exact copy of Earth (what the vast majority of people would consider the prototype for what a planet s

        • Re:Maybe (Score:5, Interesting)

          by mysticgoat ( 582871 ) on Thursday February 23, 2017 @07:02AM (#53916259) Homepage Journal

          Wow.

          TL;DR but I got through enough of it to realize that most, and maybe all, the points are cogent. Above post should be stuffed down the throats of every IAU member who voted for their absurd definition of planet until they can regurgitate those points, with meaning.

          Some astronomers are stupid. The phrase "educated beyond the level of their intelligence" comes to mind. This idiots should have been taught somewhere along the way that their expertise in one narrow field does not endow them with the authority to mess about in other disciplines like linguistics.

          • Re: (Score:2, Insightful)

            by athmanb ( 100367 )

            There's a lot of words but most of the points don't seem to make a lot of sense.

            1. "Adjective nouns" need to have similarity to "noun" but aren't necessarily a subset. Gummy bears aren't a subset of bears either.

            2. I'd like to see a citation on this. I highly doubt that you can simulate the formation of a solar system where multiple Mars analogues can coexist in the same orbit over billions of years without an accident happening to one of them.
            Alone the fact that neither of the terrestrial planets have an o

            • by Rei ( 128717 )

              1. "Adjective nouns" need to have similarity to "noun" but aren't necessarily a subset. Gummy bears aren't a subset of bears either.

              Gummy bears are not a scientific term. Besides, the IAU itself already uses the word dwarf in this manner. Dwarf stars, dwarf galaxies... but carved out an inexplicable exception for dwarf planets.

              I'd like to see a citation on this. I highly doubt that you can simulate the formation of a solar system where multiple Mars analogues can coexist in the same orbit

              False equivalenc

              • And more to the point, the biggest problem with the concept of Mars clearing its orbit is that its orbit was already largely cleared [nature.com] when it formed. According to our best models, Jupiter reached all the way in to around where Mars' orbit is today, and had cleared almost everything to around 1 AU.

                How did the asteroid belt get there, then? That's a question, not a polemic.

                • by Rei ( 128717 )

                  The short of it, Jupiter moves things around; it's very good at scattering other bodies, even large ones. First it dragged outer populations into the inner solar system, then scattered inner solar system material out, and then on its retreat pulled outer solar system material back in. It's actually a very big deal that it did that, as it brought ice into the inner solar system.

        • So, so very much is wrong with this.

          The IAU vote was narrow,

          Really? Their notes from conference indicate that the resolution "was passed with a great majority.": https://www.iau.org/news/pressreleases/detail/iau0603/ [iau.org]

          1. Nomenclature: An "adjective-noun" should always be a subset of "noun". A "dwarf planet" should be no less seen as a type of planet than a "dwarf star" is seen as a type of star by the IAU.

          No. A dry lake is not a type of lake, for example. "adjective-noun" can mean "something in the category described by adjective but resembling the nouns". You can't make Pluto a planet by playing a cheap word game.

          2. Erroneous foundation: Current research agrees that most planets did not clear their own neighborhoods

          Nothing from the IAU's resolution indicates a purpose to consider the historical conditions.

      • Good points. But they are basically off topic.

        It doesn't matter one whit what terms scientists use in their cloistered jargons. That's why they have jargons.

        It does matter when a body of scientists attempts to mold the common tongue to their narrow purposes. Which is what happened with the IAU: they overstepped their area of authority, which is astronomy, to dabble in an area where none of them have any training or standing, which is the study of natural languages, or linguistics. It makes them look like

        • by arth1 ( 260657 )

          The problem, as I see it, is that journalists have stopped translating, and echo the jargon even when it doesn't translate well.

          Even worse than the astronomical definition for planet being out of touch with the rest of the world is the astronomical definitions of gas (only hydrogen and helium), metal (all other elements), and ice (any molecules comprising both "gas" and "metal" atoms). To an astronomer, nitrogen is a metal, and methane gas is an ice.

    • Re: Maybe (Score:2, Funny)

      by Anonymous Coward

      Yeah, never understood why this Tyson guy gets so much attention. What did he ever do, except beat up some people in a ring and biting off someone's ear, and beating his wife and stuff?

      • by Nidi62 ( 1525137 )

        Yeah, never understood why this Tyson guy gets so much attention. What did he ever do, except beat up some people in a ring and biting off someone's ear, and beating his wife and stuff?

        Picturing Neil deGrasse Tyson with a face tattoo just made my day. I imagine it would either be something like a comet under his eye instead of a tear drop, or maybe something just totally out there and not even physics/space related.

    • Maybe stop changing arbitrary definitions. Pluto was always a planet. Fuck you, NASA and shitty celebrity "scientists" like Neil Tyson.

      Wow, who actually gives a shit, really? What difference does it make if Pluto is defined as a planet, a dwarf planet, an ice cube or numero uno place in the galaxy? How does that effect anyone enough to get uppity about it? Move on with your life.

    • Maybe stop changing arbitrary definitions.

      Why? If the definitions already were arbitrary then what's wrong with changing them to a different variety of arbitrary? Especially if the new definition makes more sense. We're talking about taxonomy [wikipedia.org] here, not some law of physics.

      Frankly the term planet is probably too broad to be super useful by itself. It's kind of like a genus [wikipedia.org] for space objects and we need to define the species. Jupiter and Earth are both considered planets but they aren't even remotely similar to each other aside from being big an

  • by xxxJonBoyxxx ( 565205 ) on Thursday February 23, 2017 @03:34AM (#53915895)
    >> "planet" would be a physical term, while "moon" would be an orbital term

    OK, but do you call something that orbits a star (like a, er, planet).
    • OK, but do you call something that orbits a star (like a, er, planet).

      A space station? On the account that it's no moon...

    • Re: (Score:2, Flamebait)

      by sexconker ( 1179573 )

      And what do you call things that orbit barycenters, like all things do?
      This is what happens when eggheads aren't put to task building weapons for war and aren't bullied enough - they lose all discipline and just faff about willy-nilly.

      As an egghead myself, FUCK YOU OTHER GUYS! Stop senselessly changing existing definitions and creating MORE ambiguity! You're ignoring basic principles of your field!

      • That's no egg... it's a testicle !

        You're not an egghead, you're a testicle head. And frankly for somebody who seems to think the primary purpose of science is building instruments of death (as opposed to the reality where that is a major perversion of science) - that's the kindest and most euphemistically polite term I can think of.

    • Pluto would be a Planet orbiting Sol. The Moon would be a Planet and moon of Earth. So you have Astroids, Planets, and Comets (Comets being Asteroids that have tails). Earth has one planet orbiting it, Luna or the Moon, It has many Astroids orbiting it. This system works no matter what star system you are dealing with.
       

  • by ceview ( 2857765 ) on Thursday February 23, 2017 @03:38AM (#53915899)
    The definition as proposed is prefaced as a 'geophysical definition of a planet' which already admits that it is using the definition based mostly on if the geophysics of the body is planet like. Saying pluto is a dwarf planet seems pretty good to me as it gives it a special place among planet like objects already. To increase the number of planets to over a 100 objects seems a bit silly. Astronomical bodies that orbit the sun include thousands of things, if the object is really big and clear most of the orbit and is dominant massive object that makes it a proper planet. If it is round but not a big mass then it's a dwarf planet, which still suggests it has planet like qualities.
    • to over a 100 objects seems a bit silly

      Why? Why not further classification to rocky planets and gas giant planet also? Note I come from a geophysical background.

      • by Rei ( 128717 )

        Exactly. I think Stern's always been on the right side of this. The original paper that the Stern-Levison parameter comes from has a great system laid out, where you have a bunch of adjectives that you can apply to different bodies based on their varying physical (composition, size) and orbital parameters, and you can use any combination of them as needed. Which seems to me to be so obviously the right solution.

    • by Rei ( 128717 ) on Thursday February 23, 2017 @06:39AM (#53916207) Homepage

      Saying pluto is a dwarf planet seems pretty good to me as it gives it a special place among planet like objects already.

      If they had simply stopped there, that wouldn't have been a problem. The problem is that they didn't. They declared that dwarf planets aren't planets at all - which is nonsense. Mars has far more in common with Pluto than, say, Jupiter. If anything should have been separated out, it's the gas and ice giants from the rocky/icy planets.

      Hydrostatic equilibrium is a very meaningful dividing line to split groupings on. If a body is in hydrostatic equilibrium, it's experienced dramatic geologic change in its history - differentiation, tectonics, internal heating, generally fluids (particularly liquid water), and on and on. It's the sort of place you go if you want to learn about planetary evolution or search for life. If a body is not in hydrostatic equilibrium, it's made of primordial materials, preserved largely intact. It's the sort of place you go to learn about the formation of our solar system and its building blocks.

      It's rare that nature gives you such clear dividing lines, but when it comes to planets, it has. It's not perfect - you can (and do) have bodies that straddle the border and are only partially or slightly differentiated. But in general, nature has drawn an obvious line in the sand, and we should respect that.

      if the object is really big and clear

      Is Earth's orbit clear? No, we have a huge massive object co-orbiting with us. Is Neptune's orbit clear? No, it has Pluto in it. They try their hardest to pretend that the IAU actually chose a "gravitationally dominant" standard, but that's not what they actually put in the definition. The standard in the definition is "cleared the neighborhood".

      And it's based on a false premise - that each planet cleared its own neighborhood. Which is just pseudoscience. All of our models show that Jupiter, and to a lesser extent Saturn, cleared most of the solar system, including the vast majority of the clearing around Mars, and a good fraction around Earth (lesser around Venus). Mars did not clear its own neighborhood. Nor is it gravitationally dominant in its neighborhood; the vast majority of asteroids are in orbital resonance with Jupiter and not Mars.

      And I've heard some people try to sneak around this by saying "Okay, maybe it isn't gravitationally dominant / cleared its neighbood now, but it has enough of a Stern-Levison parameter that it would have been had Jupiter not existed". First off, that's changing the definition yet again (to "would have cleared its neighborhood if no other planets were there"). But beyond that, it's abuse of the Stern-Levison parameter. The Stern-Levison parameter is built around a body's ability to clear asteroids - bodies with the current size and orbital distribution of our asteroid belt. Not protoplanets. In the early solar system it was the ability to clear protoplanets that caused neighborhoods to be cleared. Jupiter got rid of some really massive things that were forming in and near the inner solar system. There's a reason why our planetary system has such an unusual size distribution: the inner planets start getting bigger, the stop getting bigger, then get small, then debris, then something huge. That "something huge" stripped the building blocks out of the inner solar system, preventing it from becoming dominated by super-Earths. Saturn appears to have been our savior - its (delayed) formation appears to have stopped Jupiter's inward migration.

      And even just going with the Stern-Levison parameter - Neptune has a Pluto-sized body in its "neighborhood". Now, Pluto may be small compared to Neptune, but compared to Mars it wouldn't be - yet Mars has a much lower Stern-Levison parameter than Neptune. Again: the only reason Mars doesn't experience stuff like this is because Jupiter cleared its neighborhood for it.

  • Pluto will be "back" as a planet? Funny, that. It never ceased to be one so far as I was ever concerned. I'm glad valuable time was spent catching back up to what I've known.
    • by dbIII ( 701233 )
      You can call it whatever you like just as so many office workers call their PC "the hard drive" and the monitor "the computer".

      Astronomers apparently decided they wanted a little more precision in their terms when talking to other astronomers. The rest of us appear to just be getting angry when overhearing a conversation not intended for us and I don't think it really matters to us whether astronomers define Pluto as a planet or a different technical term.
  • What's the point of these taxonomical exercises? Like, who gives a fuck?

    • What's the point of these taxonomical exercises? Like, who gives a fuck?

      Those that do, and those that don't?

  • by ooloorie ( 4394035 ) on Thursday February 23, 2017 @04:09AM (#53915949)

    A planet is any body in hydrostatic equilibrium (nearly spherical) orbiting a star.

    A moon is any solid body orbiting a planet.

    • by athmanb ( 100367 )
      The problem with that definition is that it'd include a lot of random TNOs. We'd be up to like 15 planets by now, with an additional maybe 100 yet to be found in highly eccentric orbits, and probably tens of thousands more in the Oort cloud. In my opinion, those rocks hardly belong in the same category as Jupiter and Mars.

      Also, if that definition gets chosen you can look forward to decades of drama after every new TNO discovery about whether that object is in hydro-static equilibrium or not. Can you imagi
      • by athmanb ( 100367 )
        Actually I was wrong with my numbers, if you look at https://en.wikipedia.org/wiki/... [wikipedia.org] there are already 45 "likely" candidates for planetary status by your definition.
      • So what? I guess nuclear scientists should have stopped at protons and neutrons because more particles would be too hard to remember.
      • The problem with that definition is that it'd include a lot of random TNOs. We'd be up to like 15 planets by now, with an additional maybe 100 yet to be found in highly eccentric orbits

        So? That's bad how?

        Also, if that definition gets chosen you can look forward to decades of drama after every new TNO discovery about whether that object is in hydro-static equilibrium or not.

        For almost all bodies, this is pretty obvious. For objects directly on the border, you can call them "borderline" or "indeterminate". It

    • Then your solar system goes from this
      http://vignette3.wikia.nocooki... [nocookie.net]

      to this

      https://i.redd.it/q6kn9ox71tmx... [i.redd.it]
    • Is the moon orbiting the earth? Or are the two orbiting each other as they orbit the sun?
      In the case of the earth, the barycenter is within the earth. But the barycenter for Pluto and Charon is outside of Pluto...

      • Is the moon orbiting the earth? Or are the two orbiting each other as they orbit the sun?
        In the case of the earth, the barycenter is within the earth

        You just answered your own question.

  • That's a relief, Mickey's been searching for him for ages.

  • This is a much more sensible definition of planets. Not perfect, since many moons would become planets, which is confusing. But it's miles better than the current IAU definition, because a planet's planetary status wouldn't depend on where it is, and potentially where other planets are.

    Imagine a planet orbiting a star, that due to gravitational influence of other planets (or another passing star) was kicked out of the system. Under the current definition, it's suddenly no longer a planet. Likewise, if tw
    • > many moons would become planets

      They could be satellite planets. Just as we now have dwarf planets, rogue planets, terrestrial planets, and gas giant planets.

      For objects like Pluto vs. those like Earth, we could use a terms like 'major' and 'minor' (eliminating the term 'dwarf') to denote those bodies that 'dominate their orbit' or whatever measure the current definition of planet uses. Yes, this would involve also messing with the current definition of 'minor planet'.

      I really do like the idea of a mo

  • Question... (Score:5, Interesting)

    by Freischutz ( 4776131 ) on Thursday February 23, 2017 @04:25AM (#53915985)
    Personally I think the whole Pluto being a planet vs it being a dwarf planet makes about as much sense as arguing about whether American football deserves being called a football because players spend most of their time holding the ball and running around with it. Having said that, Pluto is a fascinating place regardless of it's label and, and since I'm not an astronomer, I am left wondering: Is the fight to make Pluto a planet again (or for that matter the original decision to demote it) based on sound scientific reasoning or is it just an ego driven pissing contest born injured national pride because Pluto is the only planet in the Sol system found by an American?
    • by Nidi62 ( 1525137 )

      Personally I think the whole Pluto being a planet vs it being a dwarf planet makes about as much sense as arguing about whether American football deserves being called a football because players spend most of their time holding the ball and running around with it.

      Off topic, but it's because the game evolved from a game where the primary mode of advancing the ball was either kicking it or batting it with your arms or hands.

    • The American Football is called football because it is played with an oblong leather ball that is 1 foot long from tip to tip.
      • Correction, WAS, not is. When the game started back in the days, they used a foot long ball. Now the official spec is 11.25 inches, apparently. Measured along the curve the distance is almost 13 inches.
  • You want to have a single, one-ring-to-rule-them-all to handle planets? Why? Just deem Pluto (my precious) and whatever else a planet and be done with it -- an administrative decision. No problem, just ask your local PHB secretary about these.

    Oh, you actually want a real rule? Then how about any large body that directly orbits a sun? Now, define large: diameter, atmospheric pressure (Do we call it a planet if it doesn't have an atmosphere?) "weight", mass, temperature, internal composition, a definab
    • Oh, you actually want a real rule? Then how about any large body that directly orbits a sun? Now, define large: diameter, atmospheric pressure (Do we call it a planet if it doesn't have an atmosphere?) "weight", mass, temperature, internal composition, a definable surface or what-not AND remember to define exactly what a sun is and we're done.

      All (non-accelerating) reference frames are equally valid. The sun orbits Earth just as much as Earth orbits the sun. Barycenters and whatnot.

  • The ultimate stupidity of all of this is the misguided notion that language is simply rational, and that it can be defined beforehand in its rational character by a committee decision. The fact of the matter is that language is developed by use. It's stupid that we are told "a spider is not a bug because a bug is an insect and an insect has six legs." Who ever decided that a bug meant a thing with six legs? Certainly "insect" does, but "bug" has always in actual use meant just about anything small. We somet

  • That there's something sure big enough, and sure round enough, so your momma would have to be a planet too.

  • Here's the new proposal:

    "A planet is a sub-stellar mass body that has never undergone nuclear fusion and that has sufficient self-gravitation to assume a spheroidal shape adequately described by a triaxial ellipsoid regardless of its orbital parameters."

    If that's a little too jargony for you, their 'layman's version' is simply: "Round objects in space that are smaller than stars."

    I don't know about this. By this really simplistic definition, not only are most moons now "planets", but so are a lot of asteroids and comets (of all sizes). Untold thousands of objects in our solar system will now become "planets". There's also no real clear dividing line on shape. What's the objective definition of "a spheroidal shape"? Even the Earth is far from perfectly round, so where's the line on jagged asterorids?

    Under this definition, if I throw a marble out of the ISS, i

  • "To wit: a common question we receive is, “Why did you send New Horizons to Pluto if it’s not a planet anymore?"

    I call BS on this.

    So there's all these people out there who are aware that Pluto exists, and that it was demoted to non-planet, and that we're sending a probe there, yet these same people cannot figure out why we would send a probe there? And these same people are also *unaware* that we send probes to things like the Moon and various asteroids, let alone deep space?

    Suuuuuuureee.

  • This is a prime example of how money corrupts science. The scientist in question needs grant money, and he can't get it if Pluto isn't a planet.

    Likewise, the citizens of Pluto now can't exercise their planetary rights because Pluto isn't a planet anymore. As a non-planet they aren't eligible for grant money designated for planetary authorities; they now have to get their monies from the less-funded "heavenly bodies" fund, which already has a waiting list.

    The demotion has also caused issues with the accredit

  • To properly define what a planet is, I think you need to first define what a moon is.

    Moon: a body that orbits another non-stellar body where the center of mass is within the larger body's radius.

    Planet: a spherical body that is not a moon or star. Sub-groups include gas giants, terrestrials, minor planets, double planets, etc.

    I'm probably missing some nuance or details but you get the picture.

  • During the IAU meeting which categorized Pluto as a dwarf planet (or plutoid), there were two competing definitions. One of them was functionally identical to this definition. It was struck down.

  • That's from the same guys who call oxygen a metal I suppose

  • "Pluto is a planet! Equal rights for Pluto!" - alien from Pluto, award winner in the young fan division in the Masquerade at Worldcon 2008.

If computers take over (which seems to be their natural tendency), it will serve us right. -- Alistair Cooke

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