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Space Science

Is Pluto A Planet? 39

Posted by timothy from the no-pluto-is-a-dog dept.
damiangerous writes: "This NY Times story reports the controversial decision by the American Museum of Natural History to no longer list Pluto among the planets. Although they don't actually declare Pluto's loss of planetary status outright, their newly opened planetarium classifies Pluto simply as a Kuiper Belt object. A staff member says only 1 in 10 people ask about the 'missing' planet."
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Is Pluto A Planet? More

Is Pluto A Planet?

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  • Re:Not a good precident to set (Score:1)

    by Anonymous Coward
    I don't think the phrenology analogy is apt, given that there is significant, though minority, support in the mainstream scientific community for downgrading Pluto from planet status. Taking the position that Pluto is not a planet is not astronomical quackery. The real issue is of curation and the role of a museum. I think a museum can in good faith do one of two things when presenting a topic on which there is a generally held view but not total consensus: 1: present the generally held view. (this is best when the opposing view has little, or no, well-respected backing) 2: present the generally held view, while acknowledging and exploring the opposing view. In either case, you would list Pluto as a planet. If you went with option 2 you would put a plaque nearby mentioning the other view, and then discussing the nature of scientific inquiry, the fact that scientists don't always agree, that consensus constantly shifts. By picking the minority view AND ignoring the majority view, the museum is being sneaky and does a disservice to all its visitors. Those who don't know that Pluto is a planet by the generally accepted view will come away with a false (not just distorted, but false) idea of what astronomers think about the solar system. Those who do know come away wondering where the museum's head is at, and wondering what other falsehoods, less easy for the layman to detect, the museum is pushing. I know my planets, but could I catch a contentious, minority view of the structure of quasars or black holes, or the age of the universe, if the museum tried to slip it by me? No, I couldn't. So how do I know they're not tricking me on those other subjects? By the way, this "Anonymous Coward" thing is a bit harsh, given that I've signed up but haven't received my password yet.

  • Not a valid measure of importance. (Score:1)

    by Anonymous Coward
    A staff member says only 1 in 10 people ask about the 'missing' planet.

    Quiz time!

    How many people do you think could actually list all nine (eight) planets from memory to begin with?

    My guess is somewhere around 1 in 10. (General public knowledge of science in the USA is rather poor.)

    It's kind of hard to ask about a "missing" planet if you don't know it should be there to begin with.

  • is the moon's orbit really convex wrt the sun?
    Yes, it is. I wish I had a link to point to that backs this up, but I don't. But I once attended a talk given by a NASA scientist and he spoke at some length about this fact. I was pretty surprised at the time. Now, I'd be surprised if Luna was the *only* moon in the solar system with this behavior.
  • No, he showed what the moon's orbit looks like from the point of view of a stationary observer (wrt the Sun) above the plane of the ecliptic. It looks like a circle except the radius of curvature is a bit less in some places (when it is between Earth & Sun) and a bit more in others (when it is outside of Earth's orbit). I don't know about convex vs. concave, but if you were standing on the surface of the Sun, the moon would never exhibit retrograde motion.

    I'll see if I can find something on the web that discusses this and if I do, I'll e-mail it to you.
  • It sounds like the prevalent view is that Pluto and Charon are Kuiper belt objects, but Pluto will keep it's status as a planet (per previous post, See http://www.iau.org/PlutoPR.html).

    Pluto has been called the King of the Kuiper belt, and with good reason. It's by far the largest KBO at 1140 miles. It seems that none of the twenty or so KBO's discovered so far have been larger. That's not to say that anything larger won't be found.

    http://www.astro.lsa.umich.edu/users/garyb/WWW/K BO / describes what could be the edge of the solar system proper just outside of the orbit of Pluto. It seems that Pluto survived the material sweep earlier in the solar system's history.

    I think it's desgination should stay planetary for historical reasons. Pluto is a place, a destination in many people's minds; mine included. I hope that the Pluto/Kuiper Express project will get underway again, and soon.
  • Jupiter is, IIRC, 10 times smaller than the smallest classifiable star. Pluto is just barely on the borderline of planet and planetoid (it is almost HALF the size of the moon and over HALF the size of Mercury). Jupiter is much farther from being a star than Pluto from being a planet. If Pluto is not considered a planet, there is NO WAY Jupiter will be considered a "failed star."

    Pluto also doesn't orbit like a normal planet. Most planets have near circular orbits; besides Pluto, the greatest eccentricity of the planets in our Solar system is 0.20563 (Mercury) and the rest are on the order of 0.04. Pluto has an eccentricity of 0.2444. That isn't much of an argument, but if you look at the fact that the inclination of its orbit is 17 degrees while the rest are around 1 or 2 degrees (Mercury is 7 degrees) it doesn't orbit like a planet but more like a captured object.

    In the past I have defended Pluto being a planet; but, after looking at what else is out there of around the size of Pluto and comparing them to other planets, I'm not so sure. In my opinion, though, it is almost a moot point. We know it is there, what it is made of and a lot more about it; I personally don't care how it is classified (that is only a point for astronomers and exogeologists to quibble over).

    To get back to Jupiter, though, I think it was also formed much differently than a star. I don't know if formation is part of the classification of astronomical objects, but if it is then Jupiter still wouldn't be a star even if it were larger. The planets we've found orbiting other stars have all been of around Jupiter's size, but some were over twice as large and they are still planets.

  • Reading this NYT article actually made me chuckle - I visited the Hayden on Jan 2nd, and in two hours of casual exploration, I found the place riddled with errors. Scary!

    For example, there's a quasar image, labelled as an image of the Cartwheel galaxy; sure enough, some distance away is the true Cartwheel galaxy, and no, its not labelled as a quasar, its labelled correctly. Huh? Labels are rampantly swapped in their example of objects at various wavelengths: as an astronomy grad student, I know what the Orion nebula looks like, and boy, it looks different from the Sun - its almost like someone dropped all the captions, then picked them up and stuck them back on at random. And finally, the labels for elliptical and spiral galaxies are swapped. I kid you not!

    And this was a cursory walkthrough, not a very detailed examination - things are just plain wrong! I was planning to write a note to the director, but I'm not so sure its a good idea... Apparently they spent all their money on the (extremely beautiful!) building, and had no money left to hire a couple of trained monkeys (grad students) to do some fact checking.

  • Pluto also doesn't orbit like a normal planet. Most planets have near circular orbits; besides Pluto, the greatest eccentricity of the planets in our Solar system is 0.20563 (Mercury) and the rest are on the order of 0.04. Pluto has an eccentricity of 0.2444. That isn't much of an argument, but if you look at the fact that the inclination of its orbit is 17 degrees while the rest are around 1 or 2 degrees (Mercury is 7 degrees) it doesn't orbit like a planet but more like a captured object.

    And what if Pluto is a captured planet that used to be in the inner solar system, but was flung outward early in its life?

    A few years ago i wrote a gravity simulation engine and found that occasionally inner objects that were gravitationally flung outward still orbited the central star, only at far greater distances, and with eccentric orbits. Actually, now that i think about it, i'm surprised i've never seen that theory put forward.

  • The planet Vulcan was "destroyed" when it was discovered that perturbations in Mercury's orbit were due to relativistic effects rather than due to the presense of another orbiting mass.

    For those who don't know what i'm talking about, at one point a "wobble" in Mercury's orbit caused scientists to theorize that there was another inner planet inside the orbit of Mercury. They named it "Vulcan". There's your science history lesson for the day.

  • I am not saying that one should not question scientific authority. I am saying that it is not the museum's place to re-interpret scientific authority. My position is probably best summed up in the AC reply (#11) [slashdot.org] to my comment that the museum has sided with the minority view on this issue that the museum does a disservice to the public by not presenting Pluto's place as defined by the IAU [iau.org]. There are many scientists that view Jupiter as a star that didn't have enough mass to initiate fusion; does this mean that the museum should remove Jupiter from the Planet classification and put it under a separate title such as Protostar? You can find people that advocate this, but I doubt many would change their view of Jupiter.

    Take another example: the face on Mars. There are people who are strong advocates of this, some who are technically-trained and have Ph.Ds. I don't think it is the place of the museum to make a whole extra exhibit on the Face within the context that the scientific community is undecided on this issue (on the other hand I think it would be in their place to present this in the context of mankind's romantic ideas of Mars, including such things as Percival Lowell's canal observations). It is the place of the scientists and citizens who advocate the Face to question the authority and make their case; it isn't the museum's place to do that for them.

    I also do not advocate censoring museums, but I do think that museums have a responsibility to present information accurately and within historical context, especially the American Museum of Natural History. I think that by selectively removing Pluto as being listed as a planet when the IAU classifies it as a planet is being inaccurate. Because this was a deliberated decision of omission, it does make one wonder what other museum exhibits are subject to their reinterpretation/selected-omissions.

  • Not a good precident to set (Score:3)

    by hubie ( 108345 ) on Monday January 22, 2001 @07:03AM (#490873)
    I think the museum is incorrect in their position by going against the stance of the international community [iau.org]. The museum seems to argue that the status of Pluto is a controversial open question and they are taking what they feel is the correct side of the "controversy" (they argure that they sidestep the controversy, but in doing so they are in fact taking the side opposite the predominant scientific opinion). However, as far as the international astronomical community is concerned, there is no controversy.

    If the museum wants to take this approach, they may as well include other significant sections to the museum, such as a phrenology [134.184.33.110] section when discussing current medical and psychological techniques. There are some people who still advocate phrenology, so therefore it must be a controversial subject and they should present all sides of this issue. This kind of handling of issues is just a reflection of what passes as journalism these days: no matter what issue is being presented, give equal time to an opposite opinion no matter how insignificant this opinion is considered because this is supposed to show "balanced" and "un-biased" reporting. What it does in many cases is promote very minor opinions and give them legimate status and create controversies that do not really exist.

    To present something within historical context is one thing, but an exhibit on the current state of things should reflect the current majority opinion. It might turn out that down the road the international community changes its mind about Pluto, but until then the museum should list it as one of the planets.

  • It's like the difference between hacker and cracker. You and I may know the difference, but if the world at large insists on calling computer vandals hackers, nothing we do will change their minds and we'll just be branded as eccentrics. :( Pluto may be a planet everywhere other than NY at the moment, but if you give it a bit of time, who knows?
    --
    Peace,
    Lord Omlette
    ICQ# 77863057
  • Not meaning to flame, but aren't you advocating groupthink? You are saying that to publicly question the current scientific majority is wrong. The scientific majority isn't always correct, and questioning it is what sparks further research that eventually proves one side or the other.

    You are correct that it's wrong to advocate mindless groupthink where adherence to the majority opinion is mandatory. But there's a big difference between rejecting groupthink and advocating the opinion of a small minority without letting the public even know that it is the view of only a tiny minority. Note that the original poster is not advocating silencing the minority in an appropriate venue for discussions of this type, such as scientific journals.

    I think that last point is crucial. The museum is intended to be primarily an educational institution, rather than a research one. It is right and proper for discussion of controversial issues, even ones which the majority views as largely settled, to take place in an appropriate professional venue. Museums, educational and news media, schools, and the like are not the places in which these issues should be hashed out. Those places have a responsability to present generally accepted scientific views, or at the very least present both the mainstream view and the minority view (and in that case probably with some idea of their relative popularity and which side is advancing its opinion). Presenting the minority view only, as thought the issue has been settled and the current minority view "won", is grossly dishonest and is precisely counter to the goal of education. The sad thing is that a controversy like this can actually serve as an excellent educational opportunity to demonstrate how scientific ideas develop and the museum missed it.

  • I'm not looking to flame, but I don't entirely understand where you're trying to go with this.

    How close to a sphere should the object have to be? Ignoring oblateness due to rotation or tidal effects will still leave some smaller objects with huge "mountains" resulting from collisions with realtively large bodies. We're talking about mountains which are a significant percentage of the size of the overall body. How big should such a mountain be before it means the body is no longer a planet?

    What in heck is a "concave" or "convex" orbit? Unperturbed orbits are conic sections - circles (eccentricity=0), ellipses (01). The Moon would never be considered a planet because it is clearly in orbit around the Earth (the center of gravity of the Earth-Moon system is inside the Earth), not the Sun.

    Incidentally, Pluto would ordinarily meet both a "nearly spherical body" and "orbits the sun" test.
  • I think that the fact that the center of mass of the earth-moon system is within the earth's surface disqualifies the moon from being a planet.
    Hence it is the earth's moon, not the Sun's planet.

    The moon is big enough and ugly enough to be a planet, but it needs to leave the coat tails of it mommy to count as a grownup around this solar system. Check out Space 1999 for tips on how to arrange for this. ;-)
  • ...but is instead a giant rogue hunk of green cheese that was believed to have been broken off from the moon when it was bombarded by cosmic debris some millions of years ago.

    An unmanned NASA satellite designed to bring tasty water crackers to Pluto is scheduled to launch sometime in 2002.

  • Groupthink as never questioning the "scientific establishment" is bad. Questioning is what leads to new ideas, new developments, etc. That's why we have scientists.

    Groupthink as agreeing on what we mean by the word "planet" is good. Having an established definition for a word really helps when you're trying to communicate meaning. That's why we have dictionaries.

    One museum saying "We feel like redefining "planet" in such a way that Pluto isn't covered" while the vast majority of the scientific community disagrees is just plain stupid. When most people talk about "the planets," they mean the 9 big chunks of rock, gas, and other junk that we're all familiar with. When the museum talks about "the planets," shouldn't they mean the same thing? Some small group of people propagating a conflicting definition only serves to create confusion and reduce credibility.

  • As I can see it the only things going against Pluto being a planet is the fact it is small, and the fact it is not in the same plane of orbit as the other so called planets. That's about it. Apparently there has been a group of folks who thinks if it did not form out of the original disks of material around our sun it is not a planet. Whatever. Pluto is orbiting around the sun not another planet. It itself has a moon. Pluto and its moon seem to be round and not just two big rocks. The fact is we have not sent anything to Pluto. All we know about it is that it is a fuzzy ball with another fuzzy ball around it very fare away from the sun. and that it has a non standard orbit for a planet. That is about it folks! In the end this has all been an act to force one narrow idea of what a planet is and it not. In the end that is what it comes to. I fear that it will make it harder to finally send a something to Pluto if it is not seen as a planet. This would be a shame.
  • i can,
    mercury, venus, earth, mars, jupiter, saturn, uranus, neptune, pluto, exept when neptune and pluto switch places, because their orbits cross paths, and pluto becomes closer... I happen to be an astronamy fan, but most people i know can probably name all the planets... if they can't they are gonna get a can of whoop-ass opened up on 'em... =)
  • come on people, this topic has been covered by the almight 2 skinnee Js. go on napster or whatever and search for the song "pluto" by them. with a chorus like "pluuuuuuuuuuuuuuto is a plaaaaaaanet" how can you go wrong?


    NEWS: cloning, genome, privacy, surveillance, and more! [silicongod.com]
  • Man this sucks, I remember being a little kind and they changed the pronunciation of Uranus from Ur-Anus' to UrA'nus. Now there is no planet Pluto, total suck.
  • Testing the ASCII art filter
  • ...why don't they just list Jupiter as a failed star?
  • Of course! If Mars were a planet, wouldn't it be travelling in those epicycles that (I think) Tycho Brahe was talking about? I mean, how else do you account for that darned retrograde motion!

    when they excommunicated Galileo, they did right!

    </sarcasm>
    "Titanic was 3hr and 17min long. They could have lost 3hr and 17min from that."
  • I have a friend who works at the Arizona State University geology department, Planetary Sciences, Space Photography Labratory, named Dr. David Williams (who by the way is an avid Star Trek Fan, but that's beside the point). A club that I'm in was given a tour by him of the lab, and I asked him about pluto, and he said something to the effect that Pluto's moon is NOT ROUND. Most of the tour was spent on Mars stuff, so I didn't think of getting into details, but I'm fairly confident that I am remembering properly that he said that Pluto's moon is not round...

    "Titanic was 3hr and 17min long. They could have lost 3hr and 17min from that."
  • In the past I have defended Pluto being a planet; but, after looking at what else is out there of around the size of Pluto and comparing them to other planets, I'm not so sure.

    I agree - we have traditionally considered Pluto to be a planet, but it behaves so strangely that it counts just as well as something else.

    That reminds me of the near-earth object [yorku.ca] (Asteroid 3753 Cruithne) that was considered for "moon of Earth" status...

  • Not meaning to flame, but aren't you advocating groupthink? You are saying that to publicly question the current scientific majority is wrong. The scientific majority isn't always correct, and questioning it is what sparks further research that eventually proves one side or the other. Maybe I misunderstood you, but it seems like you are advocating censoring museums, by mandating what a museum can and cannot say.
  • I really think that the basic problem is the lack of a simple definition of planet. I'd suggest that the definition have two components, and two alone:

    1) Sufficient mass/gravity to form itself into a sphere (centrifugal force and tidal effects excepted).

    2) An entirely concave orbit around a star.

    Now, this would add one new planet to the current nine -- Earth's Moon. Other than those ten objects and the Sun, all are either irregular in shape and/or in planetary orbits that cause their solar orbit to be convex.
  • 1) Yes, it's a bit fuzzy where spheres become non-spheres.

    2) Every object in the solar system does orbit the Sun, either on its own or as a consequence of its orbit around another body. Given that every one of those orbits are peturbed by other objects in the solar system, how do we distinguish which are in orbit around the Sun and which are in orbit around another body in the solar system?

    You seem to suggest looking at the center of gravity of two objects in roughly the same solar orbit. In that case, Pluto is certainly not a planet, since the barycenter (center of gravity) of Pluto-Charon is outside of Pluto. More importantly, it leaves the degree of difference between two solar orbits for such classification undefined -- without such a definition, one could argue that there are no planets, since the center of gravity of (say) Neptune and Jupiter is outside of both bodies.

    I suggest instead that we look at the nature of each object's orbit around the Sun. Of the spherical bodies in the solar system, ten have orbits that are always concave to the Sun (always convex in terms of geometric shape) -- the nine recognized planets and the Moon. Charon and many asteroids, comets, and other planetessimals also have such an orbit, but such objects are obviously irregularly-shaped.

    The point is that the Moon is not clearly in orbit around the Earth -- it has a mutually perturbing joint orbit with the Earth around the Sun, instead.
  • The nine recognized planets, the Moon, Charon, and a wide variety of planetessimals are in orbits that can be described as concave to the Sun or convex in shape, depending on perspective -- the point being that the angular velocity of the objects wrt the Sun never changes sign.

    And of that set of objects, ten are spherical due to their own gravity. So, IMVAO, the Moon should be counted as a tenth planet.
  • I've seen a few posts where people seem to be getting pretty worked up over whether or not Pluto is getting what amounts to Full Member or Associate Member status in the Solar System. The question nobody seems to be asking is: Who cares?

    Whether or not Pluto gets labeled with the "p" word is not, to my thinking, significant. It's still a major object in the Solar System, and should be mentioned during everyone's science education, just like more minor (but still significant) non-planetary objects such as Eros, Phobos and Deimos, or the better-known comets. The more interesting point to this story is not what someone chooses to call Pluto, but the proportion of ignoramuses who don't know it exists to begin with.

    For those who can't get over the question of whether or not Pluto is a planet, I suggest that we should leave its status open to question, like a certain letter of the alphabet:

    Vowels: A, E, I, O, U, and sometimes Y.
    Planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and maybe Pluto.

    OK,
    - B
    --

  • They could just realize that it's a dysfunctional deity, and calling him names will just piss him off...
  • I am reminded of a recent story I saw on Slashdot regarding new evidence that scientists had discovered two large bodies like planets orbiting a distant star in very peculiar orbital patterns that scientists thought could not exist. I say just leave Pluto's planet status alone until we can classify it better. It may not be a 'planet', but let's not classify it as otherwise until we have a more solid understanding of more of the wonderfully diverse universe in which we live. Of course, I think an open mind to this whole matter is the best approach, rather than just agreeing with everyone else that it undoubtedly is a planet, as has been mentioned above in not so simple terms.
  • I think you got convex and concave muddled up. Convex orbits always have an angular velocity which has the same sign, while concave orbits have an angular velocity that can change sign. All the planets are in convex orbits around the sun.

    Given that this is a simple case of muddling up two already confusing terms, is the moon's orbit really convex wrt the sun? Surely it has 13 cusps corresponding to the lunar months where its angular velocity wrt the sun switches sign?

  • It's Your Anus. The other pronunciation was invented by TV and schools so that kids wouldn't giggle whenever the planet's name was mentioned.
  • Well, my palm-reader says that the asteroid belt was formed when a previous civilization destroyed the planet Vulcan, and that we're all paying the Karmic cost today.

    So, maybe Ceres is like the middle of Vulcan or something.

  • Wow. So maybe it makes a kind-of "flower pattern" e.g. think of a circle and add circles around its edge. That is surprising.
  • Please post it; I'm not really zealot@linux.org, and I'm not putting my email address up while that law enforcement dude is lurking [see the Kiddie Porn threads].
  • While caffeinated_bunsen makes a good distinction about the value of groupthink in coming to common definitions of words, this isn't just a question of definitions. The definition of "planet" exists, though it may not be 100% settled. It is not a definitional truth that Pluto is a planet; rather it is a planet if and because its physical characteristics fit within the definition of "planet". In fact, none of this is relevant, as the real point is that the museum has overstepped its bounds by taking a contentious, minority position, and not even acknowledging what it is doing. This is simply deceitful. If the scientists who helped develop the displays and explanations were to try to publish an academic article that simply assumed, without argument and without even acknowledging that they were taking a minority view, that Pluto does not qualify for "planet" status, the editors and peer reviewers would laugh them out of town. But because they are dealing with the public, they feel it's ok to be, at best, sloppy and egregiously incomplete.

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