A Case of the Plutoids
Do you remember the momentous events of summer 2006? You mean you've forgotten already? It was at the International Astronomical Union's General Assembly in Prague. How could you have forgotten that? Despite all the hugely interesting astronomy and astrophysics that was being presented at the General Assembly, the main topic of interest for some surrounded the definition of the term 'planet'. This was discussed at great length on my blog at the time and I'm now totally apathetic.
One outstanding matter from that General Assembly was the need for a decision on the name for the class of dwarf planets beyond the orbit of Neptune. The term Pluton was initially suggested but rejected once the geologists pointed out that the term was already used for a type of rock. The wording of the final resolution had settled on "plutonian object" but that was also rejected in the final vote and the IAU told to go off and think of a better name. Now, two years later, they have settled on Plutoids. Don't panic, I'm sure there will be a cream for it.
A plutoid is an object orbiting the Sun at a distance (semi-major axis) greater than that of Neptune, whose self-gravity is strong enough for it to be in hydrostatic equilibrium, and has cleared the neighbourhood around it's orbit. For practical purposes, an object's absolute magnitude will be used to work out if it is to be classed as a plutoid. I worry that that will cause problems for the future.
If you are the type of person who really likes to have well defined boxes for your solar system objects, you may like to know that the two currently known plutoids are Pluto and Eris.
Comments: A Case of the Plutoids
The new rules - which are elaborated some more here - are pretty clever: If your object has an absolute mag. < +1 (i.e. is brighter), it is considered a plutoid for naming purposes (i.e. special rules apply, in contrast to smaller Kuiperoids).
At some (much) later time it may also be established whether it meets all the dwarf planet criteria (esp. sufficient roundness) - and even if not (and it thus loses the plutoid status as well) the name will stick.
Of course, there was no real need to invent a third class of planetary objects in the first place, but at least here's a set of rules now how to deal with the issue.
Posted by Daniel Fischer on Wednesday 11th Jun 2008 (17:18 UTC)
Don't worry; I most certainly have not forgotten the events of the summer of 2006. In fact, I'm attending a conference in Laurel, Maryland this summer, sponsored by NASA and JPL, on this very topic. This new term is just plain ridiculous. You're right; it sounds like some kind of disease. All this does is further confuse the situation. Why not classify "ice dwarfs" as a subclass of planets, used to describe small icy bodies in hydrostatic equilibrium that do not dominate their orbits? Do we really need so many confusing definitions like "plutoids," "ceroids," etc? How many IAU members voted on this one? Very likely less than the four percent or 424 that voted for the initial demotion. Dr. Alan Stern is right in describing this as just another backroom deal by the IAU. I hope he follows through in his idea of founding a rival organization.
Posted by Laurel Kornfeld on Wednesday 11th Jun 2008 (23:52 UTC)
Hi Laurel,
from your website I see that you are a hardcore plutophile - but I was there in Prague when this Kuiperoid met its fate. Have a look at my first-hand report. And please stop promoting conspiracy stories about "backroom deals" when the IAU press release (linked from the original posting) clearly outlines who decided what ...
P.S.: I knew Clyde personally and am a great admirer of his achievement - discovering the second dwarf planet and first plutoid! With a little better technology he may actually have found a 2nd Kuiperoid, 2005 FY9, which was pretty bright in the 1930's - had he done so, Pluto would never even have gotten the erroneous full-planet label ...
Posted by Daniel Fischer on Thursday 12th Jun 2008 (02:20 UTC)
Daniel,
I printed out and reviewed your report, which turned out to be 13 pages! Obviously, I cannot address all the points here, but I do plan to do so on my blog.
You have experienced a great honor in knowing Clyde Tombaugh, one which I unfortunately never will. However, I will point out that Tombaugh was aware of the controversy over Pluto's planet status and to the end of his life opposed any efforts at demoting it. Astronomer David Levy promised Tombaugh he would always fight for Pluto's planetary status. Tombaugh's widow and children as well as colleagues at New Mexico State University and at the Lowell Observatory took part in protests objecting to the demotion. One can only speculate, but it's more likely that had Tombaugh found 2005FY9, that too would have been considered a planet (as it still should be).
I'm sorry, but I "call them as I see them," and regardless of the IAU's insistence otherwise, both the initial vote and this latest one were backroom deals. I watched the planet debate on video, and the scene is laughable. Jocelyn Burnell's main concern was moving things along in spite of clear protests and misunderstandings. One astronomer spoke up and talked about how much he learned about the solar system from this discussion. Shouldn't he have learned that in astronomy 101? Another, after voting for 5A, asked that Pluto be included as a classical planet only to be told it was too late because the vote was already taken. Resolution footnotes first didn't count; then they did. Participants were asked on the last day to cross out terms and add other ones to the point that the entire process looked like a joke. What I saw was not, as you stated, "a striking exercise in sound and deep scientific debate."
Ninety-six percent of IAU members could not vote because of the lack of electronic voting. How can anyone assume the views of four percent are representative of the whole?
Your repeated statements that opposition to the new definition came mostly from Americans also raises the political issue. The fact is, more European astronomers are dynamicists, and more American astronomers are planetary scientists. Naturally, planetary scientists are concerned not just with where an object is but with what it is. Objects that have achieved hydrostatic equilibrium have geophysical processes that differentiate them from asteroids, a fact not taken into account in this decision.
The IAU does not have the right to make up its own grammar. There is no such thing as a "compound noun" in English. In astronomy, dwarf stars are still a subclass of stars, and dwarf galaxies are still a subclass of galaxies. What is wrong with making dwarf planets a subcategory of planets?
Informally, most people have come to view dwarf planets as small planets, whether or not that is what the IAU meant.
You claim that the more people understand about the arguments behind the decision, the more they accept it. This is anecdotal and proves nothing. I can relate multiple examples of people reacting in exactly the opposite way, in that the more they undertand about the arguments, the more they reject demoting Pluto from planethood. These examples are also anecdotal. Anyone can cherry pick stories and examples to support his or her point of view.
Your statement that Pluto never deserved planet status is an opinion, not a fact. So too is the claim that with the failure of resolution 5B, Pluto "ceased to be a planet." No, the reality is that four percent of the IAU decreed at that time that Pluto is not a planet. Their decree does not make it so, and if Pluto's lack of common features with the other eight planets were as blatant as you say they are, we would not have so many professional astronomers rejecting the IAU definition.
Finally, the conference in Maryland will not be an anti-IAU event. Both sides of the debate will be presented and recognized. What it will be is an independent meeting where both scientists and lay people who feel this issue needs further discussion (and may remain unresolved until the New Horizons flyby in 2015) will come together and voice their opinions. I have registered to attend, and I plan to blog from the conference.
The petition rejecting the IAU decision was not signed exclusively by Americans, as you suggest. Even if that were true, it in no way discredits the signatories and the valid objections they have repeatedly raised.
Posted by Laurel Kornfeld on Thursday 12th Jun 2008 (17:02 UTC)
Rather than be frustrated by your comments (English is a very adaptable language and compound nouns are fine), and on a mischievous impulse, I have decided to implement your worst fears.
By the absolute power vested in me by a vote amongst myself (100% turnout!), I have decided that the object under discussion is to be officially named Goofy and classified as a 'misunderstood blob of ice'. This is now the official definition. All mentions within the comment section of this blog, of the misunderstood blob of ice in question, will be replaced with Goofy. Mwahahahaha.
No correspondence should be entered into. Judge's decision is final. May contain nuts. Your planet may be at risk if you do not keep up repayments on your mortgage.
Posted by Stuart on Friday 13th Jun 2008 (10:59 UTC)
My planet may be at risk? So you're hiding a Death Star somewhere, I guess. And I never would have pegged you for a Sith Lord.
Begun, the Planet Wars have.
Posted by Laurel Kornfeld on Friday 13th Jun 2008 (17:39 UTC)
Posted by Stuart on Friday 13th Jun 2008 (18:27 UTC)
Some points often overlooked by Laurel and others in their struggle:
- Isn't it funny that "minor planets" have not been considered (real) planets for 150 years now. Yet the term "dwarf planets" should imply small (but real) planets!? It's not a good choice, everyone agrees (planetinos would have been my favorite), but it's well established now (200,000 Google hits), also in the technical literature ...
- The main mistake of the original (failed) planet definition committee was not to include even one astronomer who actually deals with the Kuiper Belt directly (such as discovering these things). I've been in touch with many of the Kuiper Belt key players: They all agree (and did so for many years prior to the vote) that Pluto never was a planet to them.
- The key problem with letting Pluto's planethood stay, however, would have been that it would have led to a self-destructive planet definition, inevitably. Absurd proposals aside (like defining the number of our planets as nine, period) it would always serve us dozens if not hundreds of planets. And this would devalue the whole cultural concept of a "planet" being something special - or why else are you trying to let Pluto be one? - in such a gross way that I still can't fathom why the planet definition committee's history experts didn't notice that.
- I say it one more time: The decision-making process in Prague was flawed in that there were no wide consultations before August 2006 (for which the then-executive had valid but IMHO wrong reasons). Once the proposal by the definition committee was out, the debate took place in all openness, esp. the key fight on 18 August which was not webcast (I have much of it on tape, though) but open to everyone. Outside opinions were then sought (including mine!) and frantic e-mail and phone consultations with colleagues in other countries took place. THERE WERE NO BACKROOM DEALS, period. And the result, while poorly worded, reflected the views of a large fraction of those who cared.
- The so-called petition (the one with the 300 signatures) is a joke: I actually contacted most of the well-known astronomers who signed and asked them for their reason. Intriguingly some actually agreed with the IAU decision and many had no opinion at all. But they had signed for purely political reasons - be it that they were involved in New Horizons, others were simply angry that they hadn't been consulted.
In closing I can only urge the fuming plutophiles (which do not include you!) to calm down - and to consider what one very famous member of the planet definition committee told me about my account of the Prague events when I met it (not to disclose the gender here) a year later at another conference: it was "a lone voice of reason" among all the shouting going on in the U.S. I wish two famous astronomers with names starting with an "S" would see it that way, too ...
Posted by Daniel Fischer on Saturday 14th Jun 2008 (01:10 UTC)
Dwarf planets are NOT the same as minor planets (the latter should really be called planetoids). You choose to ignore the issue of hydrostatic equilibrium as a defining characteristic. Just because you devalue this significant geophysical feature does not make it irrelevant.
What is wrong with there being hundreds of planets? Why does that "devalue" the term? There are billions of stars; that doesn't "devalue" that term. Concepts like "special" are completely subjective. Those of us who want to include Goofy--and Eris and Ceres and other objects in hydrostatic equilibrium orbiting stars--want to do so to note the unique geophysical features that distinguish them from asteroids, not to meet your particular qualification of being "special."
The petition by 300 professional astronomers is a "joke?" We're supposed to believe that the signatories put their names on it for political reasons--why? Because you say so? This is hearsay and proves nothing other than the fact that you seem to have a need to discredit these astronomers because they do not support your position.
"Lone voice of reason?" Again, a comment that is purely subjective.
When a decision is made on the last day of a two-week conference, after most participants had already left (only 424 out of 2,500 original attendees remained), and no absentee voting is permitted; when the definitions are changed and changed again to the point that even those voting are unclear as to what they are voting for, sorry that is not an open process, but a backroom deal.
I understand that you were working for an IAU publication, and therefore, your job involves representing the IAU viewpoint. There is nothing wrong with that; however, your ridicule of those who disagree with you and dismissal of very prominent astronomers make for an attitude I find condescending and quite troubling. It would be nice if we could agree to disagree while still respecting those on the other side and the integrity of their arguments.
Posted by Laurel Kornfeld on Saturday 14th Jun 2008 (06:31 UTC)
Laurel, it blatantly wasn't a "backroom deal". I watched the final vote live online as I think you did too. The term "backroom deal" is very evocative and implies lots of things that simply weren't the case here. The process was incredibly open even if you and I couldn't vote. Astronomy is far, far more open than most other fields and I don't think you are acknowledging that.
Once again, any member of the IAU could have been at that vote if they cared about it. I hardly think that 2000 out of 2500 attendees suddenly had to rush back to family emergencies. Ultimately the community in general didn't care enough to remain in Prague for the end of the conference. To be frank, I always find it quite rude when people turn up at a major conference just for their talk/session and then leave early. Of course people have their reasons - they are sooo busy and important that they can't spare two weeks every three years to tell people what they've been doing and listen to others - but it is still rude.
Ultimately any fixed definition of a planet is going to be unworkable as we find more Eris-sized objects but also as we discover very low mass stars, brown dwarfs and high mass planets. Getting all annoyed about what is currently deemed to be a solar system planet just feels like a huge waste of time. I really think that in a hundred years time people will look back on all this debate and roll their eyes.
Posted by Stuart on Saturday 14th Jun 2008 (10:50 UTC)
Laurel,
let's stop it here since facts don't seem to count much in your Universe. I actually went to great lenghts to contact many of the astronomers who signed the 'petition' and found out what drove them - and you just don't want their own words to be true and dismiss my research as "hearsay."
The same goes for your fantasizing about me working for the IAU and owing them anything - I'm as freelance a science writer as you can find. Volunteering for the (editorially independent) daily newspaper of the IAU GA was an enlightening experience, though, to which I owe a lot of valuable insights into the 'affair' that might have enlightened you, too.
I'm not actually opposed to the idea of 'promoting' some minor planets to an intermediate status, by the way. Whether hydrostatic equilibrium or rather some other key property like differentiation or presence of specific surface properties would be a good criterion for that can be debated though.
My point was that the term "minor planet" has been used for a century with everyone understanding that these are not small yet real planets but something different (closer to comet nuclei in their relative importance in the solar system). It is thus nonsensical as the IAU critics do to claim that the structurally identical term "dwarf planet" is a linguistical mistake because it 'automatically' implies an inferior but otherwise real planet.
If the latter quality is not special to you, as you claim, I all the more can't understand why you aren't happy with the status quo since 2006: the IAU actually handed you a new class of spherical bodies (and even promoted Ceres which had no lobby!). Just that these are not "planets" but called something else.
(And Stuart, please undo this Goofy nonsense - it looks like this page has been hacked and/or makes both Laurel and me look like loonies ...)
Posted by Daniel Fischer on Monday 16th Jun 2008 (00:18 UTC)
Daniel,
I'm sorry to disappoint you, but I find it odd to for you to think I would accept nothing more than your word regarding that the astronomers who signed the petition didn't really mean it as fact. Show me a public statement by each one of them repudiating the signature and stating that they now support the IAU decision, and I will reconsider. Otherwise, what reason do I have to believe your word that these professionals have risked their reputations by putting their names on a petition for something which they do not believe? If the situation were reversed, and I claimed to have personally spoken with IAU members and said they told me privately that they did not believe in the vote they took, would you accept my word as fact? I think not.
Maybe I should go to similar lengths to contact the signatories of the petition and ask why they signed it. I will see many of them at the August conference. And I will note that one, Dr. David Weintraub, wrote a book titled "Is Pluto A Planet" in which he states outright that he believes the answer is yes.
Thank you for enlightening me about your freelance status. I am curious though. Would the daily newspaper of the IAU GA print articles from viewpoints that dissent from IAU decisions?
We're actually not so far apart about the intermediate status of dwarf planets. The only area we differ on is that I believe dwarf planets should be a subclass of planets. The dwarf planet classification would still preserve the notion that these objects are different from classical planets such as terrestrial planets, gas giants, and ice giants.
I do still maintain that stating a dwarf planet is not a planet at all makes no linguistic sense. Minor planet has been used for a century informally; however, no one made any official pronouncements on whether or not these objects are subtypes of planets. Linguistically, stating that minor planets are not planets does not make sense either. That is why many people choose to use other terms such as asteroids or planetoids to describe these bodies.
As I said, I'm not happy with the IAU decision because I believe dwarf planets, including Ceres, should still be considered subtypes of planets. And I would like to see the IAU enter the 21st century and allow electronic voting.
To Stuart: If you want to continue to use the name Goofy to bring a more lightheared atmosphere, be my guest.
Posted by Laurel Kornfeld on Monday 16th Jun 2008 (05:33 UTC)
Daniel, I don't think it looks like this blog has been hacked but I appreciate that it can be an uncomfortable feeling to have any of your words changed. You'll be glad to know that behind-the-scenes your comments aren't stored as Goofy but with the P word; it only gets converted for display.
If we all look like "loonies" then it might help undermine some of the ever-so-slightly aggressive sounding tones. ;-)
Posted by Stuart on Monday 16th Jun 2008 (09:20 UTC)