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IAU Rules Pluto Still a Planet
Posted by
CmdrTaco
on Thu Aug 10, 2006 02:35 PM
from the we-can-all-rest-easy-now dept.
from the we-can-all-rest-easy-now dept.
scottyscout writes "NPR reports that Pluto has dodged a bullet.
An international panel has unanimously recommended that Pluto retain its title as a planet,
and it may be joined by other undersized objects that revolve around the sun.
Some astronomers had lobbied for reclassifying Pluto as its so tiny. And at least one major
museum has excluded Pluto from its planetary display. But sources tell NPR that under the
proposal, to be presented at a big meeting of astronomers in Prague next week for a vote,
Pluto would become part of a new class of small planets and several more objects could be
granted membership."
Related Stories
[+]
IAU Demotes Pluto to 'Dwarf Planet' Status 424 comments
davidwr writes "It's official. Pluto's been demoted. It's now one of several 'dwarf planets.' I guess we can drop the 'Period' from 'Mary's violet eyes make John stay up nights.'" (Of course, no one says you have to privately agree with the International Astronomical Union.) Several readers have contributed links to the BBC's coverage of the downgrade, as well as the usefully illustrated story at MSNBC.
[+]
Pluto Making a Comeback 439 comments
anthemaniac writes "Space.com reports that the American Astronomical Unions Division of Planetary Scientists recognizes the IAU's authority to make a new planet defintion but expects it to be altered. Separately, 300 astronomers have signed a petition saying they won't use the definition. All this stems from the discontent over how only 424 astronomers voted on the proposal that demoted Pluto. Looks like this little dog is on the comeback trail."
[+]
Why the Word 'Planet' Will Never Be Defined 141 comments
eldavojohn writes "What makes a planet a planet? Slashdot covered the great debate about whether or not Pluto qualified and Space.com now has up an article explaining why we'll never have the term 'planet' defined to a point that everyone can agree on. Divisions in the scientific community currently stand over whether or not it has to be in orbit around a star, the dynamics of the body in question and apparently the country you come from plays a part in it too. Some feel the United States is the dominant deciding factor on the definition but the IAU has not turned to democratizing the definition yet." From the article: "In the broadest terms, a planet could be thought of as anything from an 800-kilometer-wide (500-mile-wide) round rock orbiting a dead star to a colossal gas ball floating alone in space."
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I "relate to its inadequacy" (Score:5, Insightful)
-Earth's Diameter: 12,756.274 km
-Pluto's Diameter: 2306±20 km
-Jupiter's Diameter: 142,984 km
-Proportion of Earth to Pluter: 12756.274 / 2306 = 5.531
-Proportion of Jupiter to Earth: 142984 / 12756.274 = 11.209
Hmm... Jupiter has over twice the proportional difference with Earth as Earth has with Pluto. So I guess Jupiter wouldn't really consider Earth a real planet.
Personally, I think we should leave the little guy alone. Throw UB313 [wikipedia.org] in there as well. Just give it a cool name that fits in with that whole "my very educated mother..." thing.
Like the well learned and professional scientist said: "We'll call them dwarf planets or something".
--
"A man is asked if he is wise or not. He replies that he is otherwise" ~Mao Zedong
Re:I "relate to its inadequacy" (Score:5, Insightful)
But, shouldnt we also consider the fact that there is a high probability that pluto was not created from the accretion disk around the sun, from which other planets were formed ?
Especially the plane in which pluto revolves, which is very very different from other planetary planes, should also be taken into consideration, I guess.
A planet should not be just an object which revolves around a star. Rather it is something which should have formed when the star was formed. This we can very easily judge (provided we know) from the heavy metal content and the ratio, I guess.
But, I guess these should have been easily the first points in IAUs discussions. Otherwise, I am completely wrong in my assumptions
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Re:I "relate to its inadequacy" (Score:5, Insightful)
Couldn't it be argued that the accretion disk includes the Kuiper Belt?
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Re:I "relate to its inadequacy" (Score:5, Insightful)
The article also talked about how children would benefit from Pluto's planethood because it's a "misfit". Shouldn't we be classifying planets based on it's characteristics, not how it affects our culture or how people relate to it? If we classify things based on how people relate to them, we might as well call whales the "misfits of fish." It might be a totally incorrect classification, but at least obiese people have something to relate to now!
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Re:I "relate to its inadequacy" (Score:5, Funny)
Earth/5.5 = 2300km => Pluto is a planet
Pluto/5.5 = 420km => Vesta asteroid (450km) is a planet
Vesta/5.5 = 82km => 61 Danaë asteroid (82km) is a planet
61 Danaë/5.5 = 15km => 2685 Masursky asteroid is a planet
2685 Masursky/5.5 = 2.5km => 2002 JF56 asteroid is a planet
2002 JF56/5.5 = 455 meters => CN Tower (550m) is a planet
CN Tower/5.5 = 100m => Eyeglass orbital telescope would be a planet
Eyeglass/5.5 = 18m => The Titan Missle silo was a planet
Titan/5.5 = 10.7 feet => Your bathroom is a planet
Bathroom/5.5 = 2 feet => Your Mom is a planet! Oh, snap!
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Re:I "relate to its inadequacy" (Score:5, Funny)
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Future objects (Score:5, Funny)
In other news, Pixar announces corporate sponsorship of IAU.
Re:Future objects (Score:5, Funny)
That's what I love about Slashdot. Just when I think I can make out the murky bottom of the Marianas Trench with the thread's floodlights, someone shows up with a drill bit.
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Museum displays... (Score:5, Informative)
Hell, I can show you museums that show kind, gentle dinosaurs living in harmony with man [answersingenesis.org]. So what?
Pluto must be happy to hear this... (Score:5, Funny)
Don't we have this covered already (Score:5, Funny)
You know... (Score:5, Funny)
Inaccurate (Score:5, Informative)
The panel's recommendation is being reviewed by the International Astronomical Union's executive committee. In an interview last week, executive committee member Bob Williams said the definition proposed by the panel had some potential problems, and he was not at all sure if the astronomers voting in Prague this month would approve it.
"At this point, I don't feel confident enough to bet in favor of it," he said.
End of Science and the Modern Age (Score:5, Interesting)
As of now, the modern age is officially over and dystopic post-modern has begun.
Doesn't qualify. (Score:5, Funny)
KeS
Pluto, the definition of a planet, and the IAU (Score:5, Informative)
A number of years ago, the question of a definition of a planet was raised as a result of discoveries of "planets" outside of our solar system as well as a growing number of Kuiper Belt Object (KBO) discoveries in our solar system. The IAU Division of Planetary Systems Sciences technical committee wisely chose to delay a decision on a definition until a more significant body of data was obtained.
In the mean time, a well meaning but widely misunderstood suggestion from an esteemed Astronomer suggested that the planet Pluto also be given a nice round minor planet number (i.e., reserve the next multiple of 10000). His intent was to recognize the special nature of Pluto as a large member of the KBO (Kuiper Belt Object) family. He never intended to demote Pluto from planet status. However, the press took the phrase "making Pluto a minor planet" and blew the controversy way out of proportion.
An executive committee recommendation on Planet definition was formed to draft a proposal for a definition of a planet. Minutes from the IAU executive committee indicated that they favored definitions that were based on measurable physical properties over arbitrary values. For example, they signaled that they were NOT inclined to look favorably on proposals such as "limit the number of 9 planets", or proposals that set an arbitrary minimum size of a Planet.
Last January at the AAS conference, an IAU liaison announced that the IAU executive committee was scheduled to produce a report on its recommendations just prior to the IAU 26th IAU General Assembly in Prague (Aug 14 to 25, 2006). The liaison recommended that any final comments and recommendations be submitted to the exectuive committee at least a month prior to the IAU general assembly.
I was part of a group that submitted a recommendation that the definition of a Planet encompass a requirement that "it must orbit a primary fuser with sufficient mass to deform it into an spheroidal / oblate spheroidal shape". We realized that our proposal could result in redefining several bodies as planets including the large asteroid Ceres. We proposed that a new sub-class of Planets could be defined (again based on measurable physical properties) to acuminate these new dwarf planets.
We were told that a number of other groups had submitted similar of very similar proposals. I have not examined the executive committee report in detail, however it appears that IAU executive committee agrees, in principle, with such proposals.
On Tuesday 2006 August 22, 12:45-13:45 (local Prague time), in Forum Hall, executive committee recommendation on Planet definition will be presented. Based on the unanimous recommendation of the executive committee, I am hopeful of a favorable outcome form the IAU General assembly.
Held together by gravity=yes. Chemisty = no. (Score:5, Interesting)
It's been suggested that the best way to decide what is or is not a planet is to determine if the mass is held together the force of gravity or electrostatic forces (like metal bonds).
If by gravity then it should be considered a planet. If by chemisty then it's just a hunk of rock.
This makes the most sense to me.
Re:If they have such power,,, (Score:5, Informative)
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Re:If they have such power,,, (Score:5, Insightful)
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parent post overrated (Score:5, Funny)
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Re:I don't get it (Score:5, Interesting)
Because there's nothing the scientific community loves more than controversy, and this is beginning to rival the great Newton vs. Einstein debate, where some purists were not convinced that Einstein's theories were realistic. Clyde Tombaugh [wikipedia.org] discovered Pluto back in 1930 after a systematic search for planets beyond Neptune. He had to pore through photographic plates, trying to find the tiniest relative shift of an object in the starfield that would lead him to a body that was orbiting the Sun. That he found Pluto was remarkable for the time, and I think all this debate over Pluto's status is a disservice to him. Let sleeping dogs lie, let Pluto remain one of the original nine planets, and let's move on.
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Re:I don't get it (Score:5, Interesting)
No, actually, I (and most of the astronomers in my peer group) do NOT enjoy the ongoing saga. We would like the whole matter to go away.
The real answer is
Editors know that "telling people that stuff they learned in elementary school is wrong" can pull emotional strings and get a rise out of some people ... and
that leads to profit.
Sigh.
Parent
Re:I don't get it (Score:5, Insightful)
No, the overwhelming majority of astronomers were not. We don't care. Really. The issue "what is a planet?" has for most of us the same urgency and relevance that "what is a continent?" has for geologists.
There certainly _are_ topics on which there is vigorous debate in the astronomical community -- for example, the nature of gamma-ray bursts, or the accuracy and precision of the cosmological distance scale, or the physics of supernova explosions. But this isn't one of them. The issue exists solely because a very few people who (for some reason) are seeking publicity go to the media periodically with a "new twist" on this question.
Adding the question "is Pluto a planet" to the list of serious astronomical questions of the day does a disservice to those other questions.
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Re:I don't get it (Score:5, Interesting)
(If you're in astronomy for the money, you're crazy.)
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Re:More than just tiny (Score:5, Informative)
Pluto has a highly elliptical, out-of-plane orbit that crosses over Neptune's orbit, AND its orbit is 3/2 in phase with Neptune, suggesting that it was captured by Neptune's gravity.
Not quite, Pluto actually formed in the original Kuiper Belt [wikipedia.org], making it part of the original Solar System, not an object captured by Neptune. Its current orbit is the result of Neptune's gravity, yes, but Pluto was formed in orbit of the sun.
Is a "planet" something that was created with the solar system, or is a "planet" simply something that has a moon? Right now, we're using the latter definition.
Actually, neither Mercury nor Venus have moons, yet they're accepted as planets. The problem is not that an "incorrect" definition of planet is being used, it's that there is no clear definition of what constitutes a planet. This recommendation (the title is misleading, as no actual ruling was handed down) is merely part of a much larger debate on the definition of a planet [wikipedia.org].
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