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More than 300 astronomers have signed a petition denounced the IAU’s new planet definition that demotes Pluto. The petition states simply:
“We, as planetary scientists and astronomers, do not agree with the IAU’s definition of a planet, nor will we use it. A better definition is needed”
The petition, which began circulating right after last week’s vote, is one more sign that this whole debate is far from over. In another move today, the world’s largest group of planetary scientists issued a statement suggesting the definition would get worked over between now and the next IAU meeting in 2009.
While it might have seemed to the public and the press that Pluto’s demotion was a done deal (and I’m on record as saying the defintion should not be altered beyond minor tweaks to clarify) I would not bet against Pluto’s possible resurgence. Just as science promises to march forward, so too will all this bickering and posturing. And why not? It’s great fun, some of the best scientific theater of our generation.
You can see the petition’s signers here.
August 31st, 2006 at 8:19 pm
[...] Posted: Thursday, August 31, 2006 3:20 PM by Alan Boyle Categories: Space In the wake of Pluto’s demotion from the roll of solar system planets, astronomers are pointing out that a lot of the nitty-gritty details still need to be worked out - and that the plucky erstwhile planet shouldn’t be counted out quite yet. Just wait until 2009! Here’s today’s statement from the American Astronomical Society’s Division of Planetary Sciences: “Some questions have arisen over the recent International Astronomical Union (IAU) resolutions that defined three categories of bodies in the solar system: planets, dwarf planets, and small solar system bodies. These concerns are not surprising, given the long and difficult history of efforts to reach agreement on just what a planet is, and the unwillingness of nature to be categorized into neat compartments. “The Division for Planetary Sciences (DPS) of the American Astronomical Society (AAS) recognizes the authority of the IAU to render a decision, and notes that it had considerable input by DPS members in the process. “However, it is also mindful of the fact that future refinements of this definition will almost certainly be desired. All definitions have a degree of fuzziness that requires intelligent application: what does ’round’ really mean? What does it mean to ‘control a zone’? These are technical issues to be addressed by Division III of the IAU, currently chaired by Ted Bowell, a fellow DPS member. There is still work to be done, too, in constructing a definition that is generally applicable to extrasolar planetary systems. These and other changes, radical or moderate, presumably will be addressed at the next IAU General Assembly in Rio de Janeiro in 2009, and the DPS community will continue to be involved in all stages of this process. “Ultimately, the definition of a planet will come through common usage and scientific utility. There is no need to throw away current school texts; Pluto has not gone away. We will continue to explore Pluto and the other objects orbiting beyond Neptune with telescopic observations and spacecraft missions to obtain a fundamental understanding of their place in our solar system. “The DPS is the largest international professional organization of planetary scientists with approximately 1,300 members of which about 30 percent are from non-US countries.” While you’re waiting for the final answer, take a walk on the lighter side of Pluto and check out Jason Kottke’s list of new planetary memory aids. Update for 10:10 p.m. ET: Hoo boy, the Pluto protest movement is growing. Space.com’s Robert Roy Britt rounds up the resistance in this article and this blog posting. Late today, a fresh wave of criticism came to light from the Center for Space Exploration Policy Research and the Planetary Science Institute. Here’s their news release: “On August 24, a session of the International Astronomical Union (IAU) General Assembly in Prague passed a resolution re-defining the planets of our solar system. Only 428 of the IAU’s nearly 10,000 members were involved in the vote. A proposal crafted over the previous year by the IAU Planet Definition Committee would have expanded the number of objects designated as planets in the solar system to 12, with the potential for additions in the future. At the assembly, however, the proposal was modified over the course of several days to define the term with the intent of excluding all but the eight largest planets. “Neither definition was subjected to critical review by the broader planetary science community prior to the assembly. “As part of its role to examine the nature of scientific authority, the Center for Space Exploration Policy Research (CSEPR) is considering the role of the IAU and its findings, as well as a petition to reevaluate the principles for planet definition. “Just after the August 24 vote, members of the space science community pointed out serious technical and pedagogical flaws in the IAU’s definition of planets. As a consequence, a grass-roots petition was posted, stating: “‘We, as planetary scientists and astronomers, do not agree with the IAU’s definition of a planet, nor will we use it. A better definition is needed.’ “The statement was placed on the Web at http://www.ipetitions.com/petition/planetprotest and circulated by e-mail to a small fraction of the world’s astronomical research community. “In less than five days, the petition was signed by 300 professional planetary scientists and astronomers. The list of signatories (posted at the Web site above) includes researchers who have studied every kind of planet in the solar system, as well as asteroids, comets, the Kuiper Belt and planetary interactions with the space environment. Many have been involved in the robotic exploration of the solar system from some of the earliest missions to Cassini-Huygens, missions to Mars, and ongoing missions to the innermost and outermost reaches of our solar system. “Others are leading missions that are preparing for launch. The petition list includes prominent experts in the field of planet formation and evolution, planetary atmospheres, planetary surfaces and interiors, as well as international prize-winning researchers. “‘This petition gives substantial weight to the argument that the IAU definition of planet does not meet fundamental scientific standards and should be set aside,’ states petition organizer Dr. Mark Sykes, director of the Planetary Science Institute in Tucson, Ariz. ‘A more open process, involving a broader cross section of the community engaged in planetary studies of our own solar system and others, should be undertaken.’ “‘I believe more planetary experts signed the petition than were involved in the vote on the IAU’s petition,’ adds co-sponsor Dr. Alan Stern, executive director of the Space Science and Engineering Division at Southwest Research Institute. ‘From the number of signatories that the petition received in a few days, it’s clear that there is significant unhappiness among scientists with the IAU’s planet definition, and that it will not be universally adopted by scientists and textbook writers.’ “‘A key public policy question is who has the social mandate to alter the definition of something as fundamental as a planet,’ says Dr. Mark Bullock, director of the CSEPR. ‘Scientists have in the past vested the IAU with authority to name asteroids and other planetary objects. However, the word “planet” has cultural, historical, and social meaning and as such requires much broader discussion and consensus than those required for the naming of astronomical bodies.’ “The CSEPR is currently examining the nature of scientific authority, and its use and misuse in issues of fundamental concern to the public. The scientific and cultural value of the definition of planets, both within and outside our solar system, is of utmost significance. Accordingly, continues Stern, ‘To achieve a good planet definition that achieves scientific consensus will require more work.’” It should be noted that Stern is the principal scientific investigator for NASA’s New Horizons mission, which was launched toward Pluto earlier this year. Sykes is a co-investigator for NASA’s occasionally endangered Dawn mission - which will target another “dwarf planet,” the asteroid Ceres. Bullock’s specialty is planetary atmospheres, particularly on Venus and Mars. So is this a time to “teach the controversy”? [...]
September 1st, 2006 at 9:24 am
where do I sign?
September 1st, 2006 at 10:47 am
This debate shouldn’t be about Pluto. It should be about finding a scientifically-based definition of the term “planet” that not only fits what we know of our own solar system and other planetary systems at the present time, but what we can reasonably anticipate discovering in the future. As I have said in an earlier comment (and Jeffery Bennett also points out in his piece “Bulldoze Pluto? I Don’t Think So”), it is possible that we might find an object larger than Mercury in the distant reaches of the solar system, in which case we will have a “dwarf planet” which is larger than the smallest “planet”. It is also possible that we may find a pair of objects in another planetary system with a mass ratio similar to that of Pluto and Charon, but many times larger, in which case we will have to revisit the question of defining a double planet (which the original draft definition at least attempted to address). A good definition would account for these possibilities, but the IAU definition does not do so.
I must also point out that there is nothing inherently more scientific in a more limited definition of a planet (such as the IAU’s) than in a broader one (such as the original draft proposal). To argue that a given definition will result in “too many planets” is not really a rational response. What matters is that the definition has some sort of scientific basis, and, as I said above, covers future possibilities (at least as far as can be anticipated) as well as current knowledge. Whether Pluto itself is called a planet, a dwarf planet, or the King of the Kuiper Belt doesn’t really matter (though it should be in the textbooks in any case, as it’s an interesting object). What matters is that there is a sensible definition of the various terms.
My own suggestion would be to say a planet is an object independently orbiting a star which is massive enough for its interior to differentiate into layers. Conveniently, from what I have read, Pluto seems to be at just about the minimum size for this to take place, so it would either be the smallest planet or the largest subplanetary object (or dwarf planet or whatever we want to call it).
September 1st, 2006 at 2:07 pm
IMHO, an exact definition of a planet is likely to be elusive, as is often the case when trying to differentiate races or species. I see it as more of a gradation.
Planets are like pornography: I’m not sure how to define it, but I know it when I see it.
-noconflicts
September 1st, 2006 at 4:41 pm
You know, I am so not surprised by all this backlash. It was clumsily managed by the IAU in my view, switching from one definition that would have increased the size of the solar system to one that reduced it in a flash and allowing just a handful of its membership to decide.
They also failed to take into account the non-scientific but very real affection people feel for a planet that is part of their culture, even though it has nothing to do with Disney. And dare I say there is some national pride playing a part here, since Pluto is/was the only planet to be discovered from the USA.
As a kind of ironic tribute to the IAU masters of the universe, I have devised my own new mnemonic for the new order of the planets: Many Very Eccentric Men Just Sacked Unwanted Nonentity. See my blog http://skymania.blogspot.com
BTW, Mike Brown, discoverer of the nearly-tenth/twelfth planet Xenan tells me he is a fan of: Mean Very Evil Men Just Shortened Up Nature.
September 1st, 2006 at 8:10 pm
While the scientists engage in a fightback, the common people are also fighting back the IAU’s decision. There are 450 plus signatures against the IAU’s decision at http://pleasesavepluto.org along with many tools to garner support from like-minded individuals.
September 2nd, 2006 at 4:12 am
I agree with most of what has been said. The whole problem is the historical place given to orbit characteristics of an object.
Thanks to space exploration, planetary science has become a geological science. There is no doubt that - geologically speaking - a planet is round…
A planet may be a gas planet, a rocky planet, an ice planet, a small planet, a big planet. However, we can’t confuse a planet with the irregular shape of an asteroid and neither can we confuse it with a star.
There are controversies in defining a lower limit or an upper limit for sure, yet the definition of a planet should be about its geology just like the definition of a star or the definition of an asteroid should be about geology.
September 3rd, 2006 at 5:14 pm
[...] Much fervour has been generated by the recent demotion of Pluto to merely ‘dwarf’ status among the other planets of the solar system. Large protests are forming against the draft resolution voted in by a fraction of the members of the International Astronomical Union (IAU), generally claiming the new definition to be ‘fundamentally flawed’. [...]
September 6th, 2006 at 6:46 pm
Below is how you can incorporate the IAU’s stand on Planets for our Solar System (as best as can be thanks to the IAU’s explaining what it defines as a Planet more)
(http://www.iau2006.org/mirror/www.iau.org/iau0603/iau0603_Q_A2.html)
to other Stellar Systems
(http://astro.berkeley.edu/~basri/defineplanet/IAU-WGExSP.htm).
1) Objects with true masses below the limiting mass for
thermonuclear fusion of deuterium (currently calculated to be 13 Jupiter masses for objects of solar metallicity) and sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, that orbit stars or stellar remnants, dominate their orbital area and do not orbit in zones that have many other objects in them are “planets” (no matter how they formed).
2) Substellar objects with true masses above the limiting mass for thermonuclear fusion of deuterium are “brown dwarfs”, no matter how they formed nor where they are located.
3) Free-floating objects in young star clusters with masses below the limiting mass for thermonuclear fusion of deuterium are not “planets”, but are “sub-brown dwarfs” (or whatever name is most appropriate).
My petition on Exomoons http://www.ipetitions.com/petition/Exomoon/ comes right after the petition we’re talking about and is meant to prevent the what is a moon issue from spilling beyond the confines of our Solar System. Where there is consensus there is no need for the IAU to make an official definition.
With Brown Dwarfs and Starless Planets being able to have what could be called Moons http://www.sciencedaily.com/releases/2006/06/060605190412.htm and a Brown Dwarf and its Planemo ( http://jumk.de/astronomie/about-stars/planemos.shtml ) companion orbiting each other http://www.sciencedaily.com/releases/2006/08/060804084105.htm you can see that the word Moon when not used synonymously with Satellite really could use more than ever some redefinition. It’s a bigger struggle for our Solar System I see where so many Moons have been officially recognized by the IAU but not for outside of it. The IAU doesn’t officially use the term Moon and it hasn’t used the concept of it beyond the Solar System. So I say:
1) Objects outside of our Solar System that orbit objects with sufficient mass for their self-gravity to overcome rigid body forces so that they assume a hydrostatic equilibrium (nearly round) shape are Exomoons of Objects if they would have been considered planets if what they orbit would have been a Star.
2) A System Planemo is an object that orbits a Brown Dwarf or Interstellar Planet and would have been considered a Planet if it orbited a Star.
3) Multiple System Objects, objects that travel around each other are recognized as a separate class of objects.
September 6th, 2006 at 6:54 pm
I think it is time to get away from the idea of simply looking at the objects in our solar system and attempting to fit them into traditional categories. Frankly I don’t care if Pluto or Ceres or any other object is or is not a “planet”. Earth is a planet and will always be considered a planet. However, once we get a better understanding of planets in other solar systems we may find our solar system is unique, or not. There are supposed to be some solar systems with gas planets cirling their star closer than our Mercury does. Plus, there is no reason to believe it is impossible that two earth sized objects or Jupiter sized objects could share the same orbit around another star. Unlikely perhaps but not impossible. Since it’s a tie, does that make them both planets or does one arbitrarily become a moon? The problem is tradition. Tradition says that a smaller object orbiting a larger object is a moon, making the other object a planet. There is no reason why an object cannot hold the status of both moon and planet. We need better classification, it’s what humans do when they do science. Jupiter has always been considered a planet yet it is large enough to theoretically have no core, to be all gas. The pressure and internal temperatures generated could well ensure that nothing in the planet is capable of a core any size. The general public can call it a traditional planet if they want, science needs a better description. The same goes for dwarf planets. Claiming Pluto is a planet simply because it has other objects circling it is to simply hold on to tradition in the face of science. I agree it will take time to hammer out just what the difference is between earth sized planets and dwarf planets should be considered. I just think it is time to get away from the idea of simply looking at the objects in our solar system and attempting to fit them into traditional categories.
September 8th, 2006 at 9:18 am
Instead of the “sweeping out” concept, perhaps a better alternative would be that the object has stopped accreting enough material to significantly increase it’s mass.
That would serve to eliminate any objects in the Asteroid belt, and may or may not eliminate KBO’s - more study would be required to determine if there is still enough material for active accretion.
September 12th, 2006 at 1:07 am
Fine! Pluto is not a planet. We only have eight planets in our solar system. No problem.
So, what is Pluto? I’ve heard the use of Dwarf planet. So, does that means Pluto is planet? Unfortunately, the answer is No.
Who came up with this Dwarf Planet? Was it Pluto or Goofy?
To the members of the astronomical community who are endorsing “Dwarf Planet”, please repeat the following statement aloud: “I endorse the use of the term Dwarf Planet to define a non-planet. I also wish to relinquish all of my status and belongings, as I in no way deserve them.”
Let me explain my insult, for those of you who are confused or insulted. It is fundamentally incorrect to use “planet” in a label for non-planets (unless of course you are preceding planet with “Non-”.) Pluto is a “Non-Planet”, not a “Dwarf Planet”. This usage violates basic rules of grammar and word-usage. The term Dwarf Planet is a disservice to the scientific community, and to the progress of our scientific understanding.
I have no problem demoting Pluto or any other planet. Just use proper terminology, which not only gives these smaller Non-Planets a classification label, but also sets then apart from Planets.
Come on people - this high school grammar.
November 22nd, 2006 at 1:31 pm
Without going into any relevant details, may I make 2 points why the attitudes & arguments are silly.
Firstly, Pluto is not a planet. This has been known for decades now, and should have been renamed straight away. Tradition and emotion cannot, should not, must not have a place in scientific definitions. And I hope we are talking about scientists here.
Secondly, whether one agrees or not with a rule (definition, standard), never justifies not adhering to it in your (scientific) work. I don’t agree with all rules and standards we have to adhere to as software engineers within the fire alarm industry, but I can’t say: “I do it my way anyway, so there!”
Come on people, GROW UP!!!!!
November 22nd, 2006 at 1:56 pm
[...] The controversial planet-definition resolution, passed Aug. 24 in a vote of just 424 IAU members, will not stand as worded. Some 300 astronomers have pledged not to use it, and many others say it must be redone to eliminate contradictions. It will be reworked, at the least, and possibly overturned at the 2009 IAU General Assembly in Rio de Janeiro, Brazil. [...]
November 22nd, 2006 at 2:07 pm
[...] The controversial planet-definition resolution, passed Aug. 24 in a vote of just 424 IAU members, will not stand as worded. Some 300 astronomers have pledged not to use it, and many others say it must be redone to eliminate contradictions. It will be reworked, at the least, and possibly overturned at the 2009 IAU General Assembly in Rio de Janeiro, Brazil. [...]