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Experts meet to decide Pluto fate, Finally we'll know what a 'planet' is...
MizarKey
post Aug 14 2006, 06:06 AM
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One of many articles regarding the upcoming conference...

Experts meet to decide Pluto fate


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Eric P / MizarKey
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paxdan
post Aug 14 2006, 07:11 AM
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IMHO pluto is NOT a planet....

Just thought i'd kick off the inevitable debate
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akuo
post Aug 14 2006, 08:20 AM
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I'm going to start a campaign to remove the planetary status of Mercury, if they drop Pluto. It's a glorified Vulcanoid!


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David
post Aug 14 2006, 11:31 AM
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QUOTE (akuo @ Aug 14 2006, 08:20 AM) *
I'm going to start a campaign to remove the planetary status of Mercury, if they drop Pluto. It's a glorified Vulcanoid!

If we kick out Mercury, then we ought to do the same to Mars: it's closer in size/mass to Mercury than it is to Venus or the Earth, and its proximity to the main asteroid belt suggests that it should be considered merely a largish inner asteroid... laugh.gif
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Ames
post Aug 14 2006, 11:36 AM
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QUOTE (David @ Aug 14 2006, 12:31 PM) *
If we kick out Mercury, then we ought to do the same to Mars: it's closer in size/mass to Mercury than it is to Venus or the Earth, and its proximity to the main asteroid belt suggests that it should be considered merely a largish inner asteroid... laugh.gif



Ok, Jupiter is a failed sub brown dwarf...

Nick
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djellison
post Aug 14 2006, 11:45 AM
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You can think of all sorts of ways of branding when something is or isnt a 'planet'...but two things come to mind.

Does it actually matter? If we say Pluto is a planet or not, Pluto is still Pluto. Why waste the time, money and effort discusing this matter at all?

Whatever constraints you attempt to bring on the classification of a 'Planet' at some point you will have to make an arbritrary cut off point of size, shape and location and under various headings of planet, planetoid etc etc define ranges for each of these.


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ups
post Aug 14 2006, 12:12 PM
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"About 3,000 astronomers and scientists are meeting in Prague to determine the fate of Pluto and the relevance of millions of schoolbooks and encyclopaedias around the world."
_________

Much ado about nothing ~ I think they're just going to Prague for a big party.

wink.gif


IMHO Pluto should remain a planet for historical sake if nothing else.
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rogelio
post Aug 14 2006, 01:06 PM
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Concerning Pluto and the planet definition debate:

We have the same issues in biology. For example genus, species and every other taxonomic rank are, in the last analysis, arbitrary. And, yes, there are young hotshot biologists who want to scrap these categories entirely as being unscientific - and just go with cladograms (phylogenetic trees) when referring to and defining plants. But the result of such a proposal would be chaos in terms of how professionals would need to refer to plants (would a forester bother to describe an elm as the second distal branch on the third proximal Magnoliid clade, for example?). And I don’t even want to imagine how amateurs and schoolchildren would cope under such as system.

Same thing with “planets”. The concept is an arbitrary one, but ancient and culturally important and useful in maintaining interest and support for astronomy and space exploration. This is not a negligible consideration.

My solution (and the one I’m hoping comes out of the IAU meeting this week): Grandfather Pluto in as a planet. And any future discoveries (such as Xena) that are at least as large as Pluto (in diameter or mass, take your pick) become planets, too. Yes, we may ultimately have 2 or 20 more planets in the solar system, but won’t that be fun and create public interest and the impetus for more exploration?
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JRehling
post Aug 14 2006, 02:04 PM
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[...]
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remcook
post Aug 14 2006, 02:46 PM
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JRehling, that's one of the most sensible arguments I've heard in this eternal discussion :-)
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David
post Aug 14 2006, 05:22 PM
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I agree that the divisions are arbitrary, that the term planet is "cultural" (or historical) rather than scientific, and I would also suggest that -- as we learn more about extrasolar systems -- classificatory systems that make sense in terms of our own solar system may be useless when discussing other systems.

However, in practical terms, the IAU as a nomenclatorial body has dug itself into its own ditch by having one set of naming conventions for "major planets" and another set for "minor planets" and TNOs: without ever stating what the distinction was. The fatal result of this imprecision is that the IAU was forced to make a determination on where the boundary between major and minor planets was as soon as an object larger than Pluto was discovered.

It would be helpful if the IAU would stress the limits of the decision that they are going to make: not that they are going to define what a planet is for all time, but that they are clarifying, for their own purposes, what the word "planet" means in terms of their rules of nomenclature, and that they cannot rule on how the word "planet" might be used in other circumstances.
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volcanopele
post Aug 14 2006, 06:47 PM
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David brought up a good point that this is more procedural for the IAU than really anything else. Personally, I still feel that this argument over what is and what is not a planet is perhaps one of the most moronic arguments I have ever heard of. rolleyes.gif As others have mentioned, "planet" has no real scientific use.

I say let it be any natural object primarily (in other words not another planet, like Titan) orbiting a star. Yes, we have billions of planets. Do you have to memorize them all? Of course not. Since the voyagers flew past the giant planets, we have found moons that are just as interesting scientifically, if not more so. Can anyone here argue that Mercury is more scientifically important than Titan, Enceladus, Io, or Europa? But yet, because Mercury is given the gilded status of "planet" far more people are aware of Mercury and maybe a few of its properties, than they are aware of Titan or Io or any of the other interesting moons in our solar system.

And why are people having such a problem with Pluto being a planet or "Xena"? People can't contemplate a solar system with *shock* 10 planets? Did people in 1783 try to come up with definitions for planet to exclude Uranus? I mean 6 is a perfect number, there can't be more planets than the 6 known ones, obviously. So anything found outside the orbit of Saturn is a Trans-Saturnian object and not a planet, regardless of size. No, they accepted uranus as a planet, and its discovery spured on the hunt for another. Then Neptune's discovery spured the hunt for yet another.

If people want a size limiting definition, fine, go with the one rogelio suggested. Pluto is the lower limit for a planet. Anything found that is larger than it, is a planet. If there are 20 more planets, so be it. If there are thousands of potential planets, so be it. I'm not going to lose any sleep over it.


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rogelio
post Aug 14 2006, 07:08 PM
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Yes, as volcanopele and others have mentioned, "'planet' has no real scientific use"

Yet... pure "science" is not completely the point here... It's possible that NH would not now be on its way to Pluto if there hadn't been that famous "Pluto - Not Explored" stamp in the planet postage stamp series.

Money, money for space exploration could be at stake. To me its seems appropriate and worthwhile for the IAU to decide the planet question. It's ivorytoweritis to deny the significance of the power of names and categories in influencing events that occur in the real world (like funding for space missions or astronomy research). The Pluto question has gotten a lot of play all over the world, and it does seem as if laypeople want a reasonable answer.
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Guest_DonPMitchell_*
post Aug 14 2006, 09:04 PM
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An interesting point. Would NASA have been able to fund a probe to Pluto, if it had been downgraded in status?

I think if they are wise, the ITU will create a sensible definition for "planet" and then agree on a grandfather clause to keep Pluto. The debate is moronic, and it will probably turn ugly if they downgrade it.
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SigurRosFan
post Aug 15 2006, 11:18 AM
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In the news ...
QUOTE
Pluto the Ninth, Xena (2003 UB313) the
Tenth, and brighter than Pluto after that


Tom Gehrels, University of Arizona, USA

The regular asteroid observers, including amateur astronomers, are doing well with their CCDs in faint follow-up astrometry. However, large wide-angle telescopes and special equipment are needed to explore the outer solar system, including the rare objects that might qualify as planets. The searching is done with expensive telescopes by experts who are not always asteroid observers. The greatest encouragement for exploration of the outer solar system is the excitement that a new Planet might be found. Observatory directors and funding agencies are well aware of that.

This proposal is therefore to stay with the 75 years of popularly considering Pluto the Ninth, as the IAU agreed to in Manchester, and to adopt Xena as the Tenth Planet because it is intrinsically brighter than Pluto. The proposal is further that the same accurate and convenient criterion be used for naming an Eleventh Planet and so forth, namely that they be intrinsically brighter than Pluto, measured in “absolute V-magnitude.” Pluto's absolute visual magnitude is –0.76, Xena's –1.2. The present proposal is written on behalf of people who are doing the observing and discovering, who see the need for prompt recognition and the fastest return in naming. This has been explained before, in Nature 436, 1088, 2005 and Sky & Tel. 111, No. 1, 14, 2006, and this Letter has been circulated in draft form, but there has been no response from the two naming committees of the IAU. Considering roundness due to gravitational stability is complex, time consuming, subject to change, and impossible due to faintness at great distance.

A compromise for proper study and distinction of the various objects and populations is to attach to Pluto and to any new Planets also the usual comet or asteroid designation. Xena already has 2003 UB313, which eventually will be a 6-digit catalog number. The dual assignment, as Planet and comet or asteroid, will also stimulate discussion in schools and colleges of the rich variety of solar-system objects.


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