Why Pluto Is/Is Not a Planet – IAU in Rio Update – 6 August 2009 (updated Aug 10)

The International Astronomical Union is now meeting in Rio de Janeiro, Brazil. This gala gathering commenced on August 3rd (with Ceres slipping into Libra and squaring Pluto) and runs through 14th. Astronomer Mike Brown, co-discoverer of Eris, is in attendance and tweeting on Twitter as PlutoKiller whenever Twitter is not under ahack. Before Brown departed for the event, he posted his current thoughts on Pluto’s planetary status and the likelihood of an IAU debate in a blog. While suggesting the IAU is not likely to resurrect the Pluto-planet controversy in a style astrologers would deem worthy of the underworld god, he did write: “But don’t give up hope! Perhaps something will unexpectedly spill into the open and Rio can turn into a place as fun as Prague. Stay tuned…”

This blip drew my sensors into higher alert. As of the first posting of this blog (August 6th) no such debate has yet appeared. The only new posting of bodies in Pluto’s neighborhood was today’s notation on the Scattered Disk Objects Centaurs page maintained by the Minor Planet Center of the awareness of the reasonably small, highly elliptical SDO, 2009 KN30, discovered on May 25th of this year. As well, four TNO’s of non notable natures posted, discovered on the same date. The data on “Snow White,” as Mike Brown likes to call the possible dwarf planet, 2007 OR10, remains the same.

Brown’s pre-IAU blog reiterated his view that Pluto simply is not a planet. When lecturing at the University of Arizona last fall, he contended those holding the planetary view of Pluto, are quite simply, delusional. Pluto, per astronomical notation, as are Ceres, Eris, Haumea and Makemake, are dwarf planets. Pluto is not a planet.

The tweets from down at the IAU indicate that the idea that Titan has cyrovolcanoes was met with skepticism. Early IAU talk that Earth’s water came from asteroids and “it’s a good thing Jupiter has the orbit it does” was replaced with no one knows the source of Earth’s waters. Evidently, no one knows where Sedna originated either and as Mike Brown suggested in his talk, “Almost every time we try to predict something about the outer solar system we get it wrong.” So per this tweet and the comment noted above from his blog, there still is hope, right?

Astrologers balk at the declaration that Pluto is not a planet. While adamantly contending Pluto is so a planet, they neglect Eris (largely because goddess of discord is hard to work smoothly into a reading by those who have not studied her). This makes astrologers look… well stupid…. or ignorant (per my previous blog). Astrologers, to avoid being categorized as planetary conspiracy theory proponents, must: accept Pluto’s dwarf planet status, recognize the reorganization of the solar system, study the other dwarf planet effects with equal regard to Pluto, and continue to use Pluto as the potent planetary entity we know it to be. Problem solved.

The best astrological quote about Pluto’s planetary status came from Gloria Star. Star quipped that, “a Chihuahua may be small, but it’s still a dog.” Now that Gidget, the Taco Bell spokes-chihuahua has gone to the taco stand in the sky, does that mean Pluto is no longer a planet? Yes. Pluto is a dwarf planet – by astronomical terms, at least today. Get used to it.

Let’s re-evaluate the solar system. There are three planetary groupings: terrestrials (Mercury, Venus, Earth, Mars), gaseous giants (Jupiter, Saturn, Uranus, Neptune) and dwarf planets (Ceres, Pluto, Charon, Eris, Makemake, Haumea and who knows about Sedna and Snow White?). While pondering if size matters in the solar system, I constructed a collection of plots of the physical data of the solar system. While on a late night tear, I decided to examine plots involving the logarithms of the bodies. Lo and behold, an affiliation between the dwarf planets, based upon density, came to light. The lack of proximity of Ceres to the other dwarf planets no longer matters. The relationship has been found. Consider the following two plots involving the diameter of the planets plotted aganst the log of the density (how tightly packed, symbolically representing focus, intention) of the primary “planetary” bodies.

diameter versus log of Density









The same effect as above can be witnessed with a plot of mass versus the log of Density.

As well, note the following graphic argument for the potency of dwarf planets based upon the ratio of density to gravity:









Similar effects are seen with plots for mass/Gravity

Ultimately, it does not matter what the bodies are called. A name is a name. Pluto is a dwarf planet. So what? Big deal. Call it what it is and while you’re at it, start using Eris. Otherwise, when astrologers ignore the snub-sensitive Eris and call Pluto a planet, they appear superstitious and conspiratorial. We wouldn’t want that. So let’s be the ever-evolving, open-minded collection of humanity we profess to be and let’s start with Pluto. Still, given the exploration of physical planetary characteristics, I think of Pluto and Eris and more as planets, deluded though I may be. In public, though, I make sure I make it known I am aware of the actual scientific status. I don’t want to be “plutoed” for my view of Pluto.

Update 8/6: Dr. Gonzalo Tancredi suggests 14 dwarf planets, 8 probable, 19 unclear. Suggested diameter > 450 km. Astrologers are really in trouble now!

Update 8/7: Today on the MPC TNO post a new body appeared. The same happened with SDO’s and centaurs. Mike Brown tweeted that the panel on Icy Bodies in the Solar System is complete with no discussion of what a planet makes.  The tally for talks dedicated to specific dwarf planets: Haumea 4, Pluto 2, Sedna 1 and nada for both Eris and Makemake. Damn, shouldn’t they know better than to snub Eris?

Update 8/10: Well, it appears that the IAU made it through the part of the gathering that might rile up any new debate on planets, Pluto, Eris or dwarf planets. I must admit I am disappointed. If you search Mike Brown’s planets you can read his summary of the IAU and see his promise to go on in the future about the way the IAU has handled the planet debate. So, I’m guessing we now need to wait for more data on “Snow White,” which to me seems unlikely to stir more debate, or for something new and odd and way beyond known models to appear. I suspect we may not have long to wait – at least in the scheme of eternity or the length of orbit of a plutoid-class dwarf planet. More on Pluto from my corner soon.

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9 Responses to Why Pluto Is/Is Not a Planet – IAU in Rio Update – 6 August 2009 (updated Aug 10)

  1. It’s Brown who is delusional. He continues to deny that there is an ongoing debate in spite of the fact that hundreds of professional astronomers signed a formal petition rejecting the IAU definition and continue to refuse to use it. You are right in viewing dwarf planets as a subclass of planets, but Brown and the “official” IAU definition specifically state that dwarf planets are NOT planets at all. This is a significant part of the problem.

    Pluto is a planet because it is spherical, meaning it is large enough to be pulled into a round shape by its own gravity–a state known as hydrostatic equilibrium and characteristic of planets, not of shapeless asteroids held together by chemical bonds. These reasons are why many astronomers, lay people, and educators are either ignoring the demotion entirely or working to get it overturned. Using this broader definition gives our solar system 13 planets and counting: Mercury, Venus, Earth, Mars, Ceres, Jupiter, Saturn, Uranus, Neptune, Pluto, Haumea, Makemake, and Eris.

    There is no “official” scientific status of Pluto or any of these other bodies. Four percent or 424 IAU members, most of whom are not planetary scientists, voted for the dwarf planets are not planets definition in 2006 and an equal number of scientists continue to dispute their definition. The IAU definition becomes legitimate only if enough people consent to it, and this has not happened.

    I am a writer and amateur astronomer and proud to be one of these people. You can read more about why Pluto is a planet and worldwide efforts to overturn the demotion by Googling my site, “Laurel’s Pluto Blog.”

    • matrixpsedgwick says:

      Hey Laurel,

      Well those like Sykes here at U of A and Alan Stern and of course those at Lowell certainly want Pluto to stay a planet. Any astrologer who has had a Pluto transit knows for a fact it’s no small burrito.

      For those who have not read Laurel’s blogs, I strongly recommend them.

      Finally, I still contend something(s) is out there that will change the present planet definition.

    • Raymond Andrews says:

      Pluto is a kuiper belt object and transneptunian (it orbits beyond Neptune,and so it is a transneptunian). It’s one of thousands of kuiper belt objects, transneptunians just like Ceres is one of thousands of asteroids and Chiron is one of dozens of centaurs.

      the explanation of why Pluto doesn’t meet the criteria makes a lot of sense.

      Pluto got the same treatment Ceres got. Ceres was classed as planet for half a century and then it got demoted after they realized that it was not a planet but a new type of object.

      Now Pluto and Ceres are equals as dwarf planets thanks to the discovery of Eris which forced astronomers to come up with a definition of a planet which led to the destruction of the old system and creation of a new system. redefining,challenge the status quo seems like good keywords for Eris.

      we just have more knowledge of the solar system and know that solar system doesn’t end with Pluto and that there are objects that orbit like Pluto and many others that orbit beyond Pluto. We know that Chiron is not from outside our solar system, and that it has its roots in the kuiper belt. We now know that Chiron is not alone as a centaur. There are over 40 centaurs discovered.

      We now know why Pluto’s orbit is far more eccentric and inclined than the other planets. After the discovery of the kuiper belt and the discoveries of plutinos, we now know that Pluto’s orbit is much different because it’s a kuiper belt object and plutino.

      the following is from Dr. Michael Brown, the co-discoverer of Eris and other large transneptunians

      “Here are some of the issues that have come up:
      What about Pluto crossing Neptune’s orbit?
      Partly this issue has come up from an incorrect statement in an AP wire story which says that Pluto is autmatically disqualified because it crosses the orbit of Neptune. Untrue. Pluto is disqualified because it is in the Kuiper belt but has not cleared out the Kuiper belt nor accumulated most of the mass in the asteroid belt, nor does it dominate the Kuiper belt. Pluto is part of a vast population and is rightly classified with that population where it belongs.
      But surely this means Neptune has not cleared out Pluto and thus is not a planet, right? No. The problem here is simply with the hasty way in which the final definition was drafted, not with the concept, which is quite solid. And the concept is more important than a lawyerly reading of the definition. Neptune has a mass more than 8000 times greater than that of Pluto, and, in fact, totally dominates Pluto’s region of the Kuiper belt. Much of the material in the Kuiper belt has indeed been tossed aside or accumulated by Neptune, but a very special region (“the Plutinos”) have actually been captured by Neptune instead. We now know that Neptune formed much closer to the sun than where it was today, and, as Neptune moved out, it pushed these Plutinos out with it while forcing them into a peculariar orbit where they orbit the sun precisely twice for every three orbits of Neptune. Pluto is the largest of the Plutinos, and it and the others only exist where they do because of the dominance of Neptune. While a lawyer could make a case that Pluto has not been cleared by Neptune, the concept and intent of the definition is sound, and Neptune’s total domination of Pluto’s dynamics is actually an excellent demonstration of precisely the concept the definition is meant to convey.”


      So just because Pluto is round doesn’t make it a planet. It doesn’t clear its neighborhood. It is no way near large enough to dominate the kuiper belt.

      if Pluto is put back on the map as a planet, then why not Ceres get its planethood back too. It was classed as a planet before Neptune was discovered.

      removing Pluto from planethood doesn’t take away Pluto’s astrological significance. It just opens the doors to consider that Pluto’s fellow transneptunians also have significant astrological influences. Size doesn’t really matter either. After all, astrologers think of Pluto as very powerful (the planet of power) even though it is so much smaller than our Moon….not even coming close to the size of our Earth. There can be objects smaller than Pluto that are even more powerful. Pluto doesn’t have the monopoly on power,transformation,intensity,rebirth,resurrection,elimination,and other things assigned to Pluto….not with thousands of transneptunians exist in the solar system….not with the existence of quite a few big ones….2 that comes close to Pluto’s size (Makemake and Haumea) and 1 that is even larger (Eris).

      I say that the door of 21st Century Astrology has been opened with the discovery of the kuiper belt in 1992 and the discoveries of large Kuiper belt objects starting in 2000.

  2. BogdanKr says:

    90% of astrologers I know personally using this new planet say “There is a comet Eris, and a planet called Proserpina/Persephone/Kora”. So I agree that astrologers do not use “Eris”. And, contrary to your opinion, this is very wise of them.

    • matrixpsedgwick says:

      There are asteroids named Persephone and Prosepina and more. Mike Brown who had the naming rights to Eris, said it should have been named Persephone by all rights but could not because the asteroids gobbled up those names. I’ve not seen any information indicating Eris has cometary characteristics. It could, but won’t get close enough to the Sun for those to appear. Chiron also falls into comet characteristic territory.

      As for snubbing Eris, unwise methinks. Not only does she offer invaluable astrological insight, according to her myth snubbing her tends to create a heap of havoc. And of course, no one has to use it or agree with the terminologies. What we know of Eris’ physical nature at this point is little, indeed.

      Along the same line, it came out yesterday that Haumea has spots.

  3. BogdanKr says:

    About the name, shortly after official annmocucement of her discovery, in summer of 2005, there were polls conducted by astronomy and science portals, and the greek Persephone and roman Proserpina was clear winner of all these polls, so we know what the name the public wants. I agree, we know not really much about her. But we do know astronomically that it is white in colour and coated in jewels. And her orbital parameters resemble greek myth on ‘abduction’ of Persphone. Most similar to venus.
    IAU is organisation created by astronomers to promote international cooperation among astronomers. They recommend the standards to astronomers, and if they are non controversial, astronomers follow it. But it has no legal authority on naming celestial objects, less the planets. They cannot enforce their recommendations even on their own members, forget non-assiociated astronomers (professional or amateur) or astrologers. As to the planets, if you call “right to name” as to “right to name by your liking”, there were only three earlier precedents in modern times. In all 3 of three (100%) of them astronomical community denied this right to the discoverer. The first, official and *legal*, was James, George, Peter, or what? Georgium sidonium… Have you heard it used in the last century? Even british astronomers (legal for them) gave it up quite a time ago. Nowadays everybody uses *Uranus*. The socond, Leverrier, have you heard it used latelty? No. All the time… Neptune. So actually the third of discoverers, Tombaugh, simple allowed the public make suggestions, and chosen the one that most of the interested people liked to be right. So now we have Pluto, you hear it used all the time. And all three discoveres, even those that their propositions were turned down, definitely are not forgotten. Quite a contrary. :) So astrologers that use this planet as often as other planets, call her like it works for them, but thjey also know who the discoverer is, and who gets the credit…

    • matrixpsedgwick says:

      There was quite the naming controversy around Uranus (and Neptune). A great book on the topic, The Neptune File by Tom Standage. The French wanted Uranus to be named Neptune. And of course, Minerva seemed to pop up every time. Pluto almost did not get the name Pluto because of a popular laxative – spring water from French Lick, Indiana, called Pluto Water and very popular in those days.

  4. BogdanKr says:

    I also had a feeling that we get Pluto named as Pluto by a lot of luck. The astronomers naming asteroids were “using up” the store of mithology names so fast and vast, that it was straw of the draw that it wasn’t already used up until the planet later named Pluto was discovered. With this new planet we haven’t been so lucky, as an Eris (for obvious reasons) was left unused with very little company indeed. At least majority of astrologers haven’t ever heard that “Persephone” “Proserpina” “Cora” were “used up”, so some of us don’t bother preserving astronomers’ “plays in the sand” at the cost of our “harm”. And, as astronomers haven’t allowed us to take part in this particular “play in the sound” codenamed “official naming of the planet”, why should we, anyway?

  5. matrixpsedgwick says:

    Actually, astrologers have played a part in the naming of several centaurs. Myself, I’ve had a hand in the naming of two. So if we petition some of the more name conscious astronomers, they do not entirely discard our input.

    I wrote Mike Brown asking about the name for Haumea. I used astrological notation and he replied that I was very close… sort of I was, but I was not aware of Haumea… I petitioned for Pele, but we got her sister… probably even better now that I’ve had time to wrap around it.

    So, maybe it’s the role of astrologers who care about the archetypes to petition the astronomers who appreciate the social value (at least) of the name of a celestial body.

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