Patrick I read the link you provided in your news letter, http://planetary.org/news/2004/planet_vote.html Personally, I dont feel I should vote because my decision would be based on emotion or something non-scientific and therefore I dont feel justified in voting. I believe I read where you expressed your opinion that Pluto is not a planet. You must have set in your own mind some criteria where the cut off is between a planet and the next level down; planetoids or asteroids. What criteria do you think should be considered in making such a judgment? Anyone else can answer for that matter. JG --------------------------------- Do you Yahoo!? Win a $20,000 Career Makeover at Yahoo! HotJobs
Jim, IMO, this is a tempest in a teapot. No matter what the criteria are, someone will disagree. Too, there is no "Encyclopaedia Galactica" that spells it out as an Absolute Truth, so even criteria applied by the world's leading authorities is still thus, 'arbitrary'. If it looks like a duck, quacks like a duck, it's a duck. Pluto's a planet, Sedna's a planet. Big deal. --- Jim Gibson <jimgibson00@yahoo.com> wrote:
What criteria do you think should be considered in making such a judgment? Anyone else can answer for that matter.
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Here are my criteria for planethood: 1: Size large enough to form a fairly solid spheroid. (This size will differ according to material density) 2: Orbits a star directly, not indirectly such as a natural satellite of a larger non-stellar body. 3: Was never on the H-R diagram during it's "lifetime". (this to exclude neutron stars, white-dwarf cores, black holes and such, that may in fact be some form of "solid". --- Chuck Hards <chuckhards@yahoo.com> wrote:
Jim, IMO, this is a tempest in a teapot. No matter what the criteria are, someone will disagree. Too, there is no "Encyclopaedia Galactica" that spells it out as an Absolute Truth, so even criteria applied by the world's leading authorities is still thus, 'arbitrary'.
If it looks like a duck, quacks like a duck, it's a duck.
Pluto's a planet, Sedna's a planet. Big deal.
--- Jim Gibson <jimgibson00@yahoo.com> wrote:
What criteria do you think should be considered in making such a judgment? Anyone else can answer for that matter.
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To Chuck's definitions of planet I would add, for our solar system, "not a member of the Oort Cloud or the Kuiper Belt." After Ben Bromley's talk at the SLAS meeting, we know that at least in the view of many astrophysicists, planets form through collisions of planetesimals. So it's important to distinguish a full-blown planet from these objects. Necessarily that involves somewhat arbitrary size distinctions. But we may be able to define the Oort Cloud and Kuiper Belt. If the discoverers of Sedna are right, Sedna is part of the Oort Cloud. I don't think Pluto is -- at least, it isn't anymore. An important factor in deciding what's in the planet club and what's not is public perception. The fact that generations of school kids have learned "Mercury, Venus, Earth, Mars, Jupiter, Saturn, Neptune and Pluto" should play a big role in the debate. We come off appearing arrogant if we insist, "No, everybody got it wrong! We have to take Pluto off the list!" -- especially if we do it without a compelling argument. After all, Pluto has been considered a planet for a long time, we celebrate Clyde Tombaugh's discovery, and it is not now part of a cloud of similar objects. As Carl Sagan said, "Extraordinary claims require extraordinary evidence." In the is/isn't a planet debate, it's an extraordinary claim to say Pluto should be removed from the pantheon. It's also an extraordinary claim to add a planet. Sedna really isn't big enough to meet the definition of planet in the public mind, I suspect. Undoubtedly, sister planetesimals will be discovered in the far reaches of the solar system. By requiring that a planet not be part of the Oort Cloud, we eliminate the extraordinary claim that Sedna should be counted as the tenth planet. And this allows Pluto to remain listed. Just some thoughts. -- Joe
Joe: --- Joe Bauman <bau@desnews.com> wrote:
To Chuck's definitions of planet I would add, for our solar system, "not a member of the Oort Cloud or the Kuiper Belt."
Why? That criteria seems completely arbitrary. As does the collisional formation criteria, and the historical "planet club" members. All those additional criteria are semantics and serve only to muddle the issue in the minds of the public. Again, if it looks like a duck, quacks like a duck, its a duck, no matter if it was cloned in the lab or hatched naturally. In the zoo or in the wild. In the Oort cloud, Kuiper belt, or the West Bank. The Solar System is a tiny, statistically insignificant sample and no conclusions can really be drawn from it. Joe, remember that a scientist's goal is to take a question and earn a living from it. Of course planetary scientists are going to bury us in irrelevant details that only they get excited about. I know enough professional scientists to say that most take their own work with a grain of salt, only the public gets their shorts in a knot over stuff like this, for the most part.
After Ben Bromley's talk at the SLAS meeting, we know that at least in the view of many astrophysicists, planets form through collisions of planetesimals. So it's important to distinguish a full-blown planet from these objects. Necessarily that involves somewhat arbitrary size distinctions. But we may be able to define the Oort Cloud and Kuiper Belt. If the discoverers of Sedna are right, Sedna is part of the Oort Cloud. I don't think Pluto is -- at least, it isn't anymore.
An important factor in deciding what's in the planet club and what's not is public perception. The fact that generations of school kids have learned "Mercury, Venus, Earth, Mars, Jupiter, Saturn, Neptune and Pluto" should play a big role in the debate. We come off appearing arrogant if we insist, "No, everybody got it wrong! We have to take Pluto off the list!" -- especially if we do it without a compelling argument. After all, Pluto has been considered a planet for a long time, we celebrate Clyde Tombaugh's discovery, and it is not now part of a cloud of similar objects.
As Carl Sagan said, "Extraordinary claims require extraordinary evidence." In the is/isn't a planet debate, it's an extraordinary claim to say Pluto should be removed from the pantheon. It's also an extraordinary claim to add a planet.
Sedna really isn't big enough to meet the definition of planet in the public mind, I suspect. Undoubtedly, sister planetesimals will be discovered in the far reaches of the solar system. By requiring that a planet not be part of the Oort Cloud, we eliminate the extraordinary claim that Sedna should be counted as the tenth planet. And this allows Pluto to remain listed.
Just some thoughts. -- Joe
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Then, how about Object Kowal? (It may have a different name now, but that is what it was called when it was discovered.) Brent --- Joe Bauman <bau@desnews.com> wrote:
To Chuck's definitions of planet I would add, for our solar system, "not a member of the Oort Cloud or the Kuiper Belt."
After Ben Bromley's talk at the SLAS meeting, we know that at least in the view of many astrophysicists, planets form through collisions of planetesimals. So it's important to distinguish a full-blown planet from these objects. Necessarily that involves somewhat arbitrary size distinctions. But we may be able to define the Oort Cloud and Kuiper Belt. If the discoverers of Sedna are right, Sedna is part of the Oort Cloud. I don't think Pluto is -- at least, it isn't anymore.
An important factor in deciding what's in the planet club and what's not is public perception. The fact that generations of school kids have learned "Mercury, Venus, Earth, Mars, Jupiter, Saturn, Neptune and Pluto" should play a big role in the debate. We come off appearing arrogant if we insist, "No, everybody got it wrong! We have to take Pluto off the list!" -- especially if we do it without a compelling argument. After all, Pluto has been considered a planet for a long time, we celebrate Clyde Tombaugh's discovery, and it is not now part of a cloud of similar objects.
As Carl Sagan said, "Extraordinary claims require extraordinary evidence." In the is/isn't a planet debate, it's an extraordinary claim to say Pluto should be removed from the pantheon. It's also an extraordinary claim to add a planet.
Sedna really isn't big enough to meet the definition of planet in the public mind, I suspect. Undoubtedly, sister planetesimals will be discovered in the far reaches of the solar system. By requiring that a planet not be part of the Oort Cloud, we eliminate the extraordinary claim that Sedna should be counted as the tenth planet. And this allows Pluto to remain listed.
Just some thoughts. -- Joe
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Brent, I've either never heard of it (Very possible) or forgotten what it was (highly likely). Named after Charles Kowal, I'm guessing? What I wanted to say is that apparently Dr. Bromley's criteria seem heavily skewed in favor of defending the "classical" planetary definition. Once you start tossing-in formation criteria then the whole thing is blown wide-open, unnecessarily. I'd be willing to bet that there are thousands of ways that planets are made; thus my reluctance to take a stand this early in the evolution of human understanding. Especially when you use only one detailed example to build your model from. --- Brent Watson <brentjwatson@yahoo.com> wrote:
Then, how about Object Kowal? (It may have a different name now, but that is what it was called when it was discovered.)
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Yes, Kowal refers to Charles Kowal. He took photographic plates of Quaoar in the early 80's while looking for planet-X. The plates were used by Brown & Trujillo of Caltech in 2002 to determine Quaoar's current location. Now as to what is a planet?; many Trans-Neptunian Astrologers are already using Sedna, Quaoar, Ixion, Varuna, etc in their charts & what have you...if it's good enough for them, it's good enough for me! Just kidding by the way. Dave On Tuesday, May 11, 2004, at 11:19 AM, Chuck Hards wrote:
Brent, I've either never heard of it (Very possible) or forgotten what it was (highly likely). Named after Charles Kowal, I'm guessing?
What I wanted to say is that apparently Dr. Bromley's criteria seem heavily skewed in favor of defending the "classical" planetary definition.
Once you start tossing-in formation criteria then the whole thing is blown wide-open, unnecessarily. I'd be willing to bet that there are thousands of ways that planets are made; thus my reluctance to take a stand this early in the evolution of human understanding. Especially when you use only one detailed example to build your model from.
--- Brent Watson <brentjwatson@yahoo.com> wrote:
Then, how about Object Kowal? (It may have a different name now, but that is what it was called when it was discovered.)
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People living "now" tend to think that the way things are is the ultimate evolution. Of course they are wrong, in every aspect, unless the world ends immediately... My daughter was watching "A Wrinkle in Time" last night, and I thought 'wouldn't it be funny if it turned out that the "paranormal" advocates were right all along, and science was just a curiosity peculiar to humans current state of evolution?' Remember Isaac Asimov's definition of "magic"? ;) --- David L Bennett <dlbennett@mac.com> wrote:
Now as to what is a planet?; many Trans-Neptunian Astrologers are already using Sedna, Quaoar, Ixion, Varuna, etc in their charts & what have you...if it's good enough for them, it's good enough for me! Just kidding by the way.
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On May 11, 2004, at 9:54 AM, Joe Bauman wrote:
[...]
As Carl Sagan said, "Extraordinary claims require extraordinary evidence." In the is/isn't a planet debate, it's an extraordinary claim to say Pluto should be removed from the pantheon. It's also an extraordinary claim to add a planet.
Some historical perspective may be pertinent. Imagine how extraordinary it must have been to add Herschel's planet (aka Uranus) after the pantheon of planets had been established for thousands of years. Yet it was correct to add it, for calculation of its orbit indicated that it was indeed a planet. The first asteroids, discovered about twenty years later, were initially considered planets. The orbit of Ceres fit the Bode-Titius "law," and thus occasioned little surprise. But then the subsequent discoveries fit in the same place in that scheme. When so many asteroids were found, and mass calculations showed them to be small--Ceres has 1/5000 the mass of the earth--astronomers reconsidered and downgraded them. Yes Pluto has a long tenure as a "planet." But seventy years is vanishingly small compared to the tenure of the five known from antiquity. And for more than half of that tenure there has been discomfort with this classification. Pluto's biggest claim to planetary status did not pan out--it did not prove to be the source of Neptune's orbital perturbations. When Charon was discovered, and the size of Pluto could finally be inferred, astronomers were shocked how minor it was compared to the other planets. The mass of the earth is 6.0 x 10^24 kg. Mercury, the smallest planet other than Pluto, has mass .33 x 10^24 kg. Then a long step down is Pluto, with a mass of 0.015 x 10^24 kg. This is 1/400 the mass of the earth, and about 12.5 times the mass of Ceres. Pluto is closer to Ceres in mass than to the earth. Another way to look at this is Mercury has 22 times the mass of Pluto, and Pluto has 12.5 the mass of Ceres. Again, Pluto is closer to the minor planets than it is to the majors. Instead of having gimmick votes, astronomers should use a system that proves most convenient for the study of the subject, and hopefully will be helpful as they catalog exoplanets. I don't know what that system would be. The study of astronomy will continue to surprise us, and classifications will need to be updated. Half a century ago galaxies were called "spiral nebulae" because the Milky Way was thought to be the universe. Freezing a classification scheme regardless of new discoveries is what produced astrology, not astronomy. Regards, Jim ---- Jim Cobb james@cobb.name
An excellent posting, Jim, well thought-out and to the point. Again, however, the bulk of the statement revolves around the solar-system (and human history-I can't quite work that into the equation) as a basis for continuing debate. And again I have to call attention to the fact that one planetary system (that is known in detail, we must discount those around other stars, detected by indirect means) is a poor statistical sample, when held against the remainder of the universe. It's just way too early to say for sure what is, and what isn't a planet, and it only really matters to those who need labels, for whatever reason. --- Jim Cobb <james@cobb.name> wrote:
On May 11, 2004, at 9:54 AM, Joe Bauman wrote:
[...]
As Carl Sagan said, "Extraordinary claims require extraordinary evidence." In the is/isn't a planet debate, it's an extraordinary claim to say Pluto should be removed from the pantheon. It's also an extraordinary claim to add a planet.
Some historical perspective may be pertinent. Imagine how extraordinary it must have been to add Herschel's planet (aka Uranus) after the pantheon of planets had been established for thousands of years. Yet it was correct to add it, for calculation of its orbit indicated that it was indeed a planet.
The first asteroids, discovered about twenty years later, were initially considered planets. The orbit of Ceres fit the Bode-Titius "law," and thus occasioned little surprise. But then the subsequent discoveries fit in the same place in that scheme. When so many asteroids were found, and mass calculations showed them to be small--Ceres has 1/5000 the mass of the earth--astronomers reconsidered and downgraded them.
Yes Pluto has a long tenure as a "planet." But seventy years is vanishingly small compared to the tenure of the five known from antiquity. And for more than half of that tenure there has been discomfort with this classification. Pluto's biggest claim to planetary status did not pan out--it did not prove to be the source of Neptune's orbital perturbations. When Charon was discovered, and the size of Pluto could finally be inferred, astronomers were shocked how minor it was compared to the other planets. The mass of the earth is 6.0 x 10^24 kg. Mercury, the smallest planet other than Pluto, has mass .33 x 10^24 kg. Then a long step down is Pluto, with a mass of 0.015 x 10^24 kg. This is 1/400 the mass of the earth, and about 12.5 times the mass of Ceres. Pluto is closer to Ceres in mass than to the earth. Another way to look at this is Mercury has 22 times the mass of Pluto, and Pluto has 12.5 the mass of Ceres. Again, Pluto is closer to the minor planets than it is to the majors.
Instead of having gimmick votes, astronomers should use a system that proves most convenient for the study of the subject, and hopefully will be helpful as they catalog exoplanets. I don't know what that system would be.
The study of astronomy will continue to surprise us, and classifications will need to be updated. Half a century ago galaxies were called "spiral nebulae" because the Milky Way was thought to be the universe. Freezing a classification scheme regardless of new discoveries is what produced astrology, not astronomy.
Regards, Jim ---- Jim Cobb james@cobb.name
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The problem with allowing just anything in the Oort cloud into the planet club is that probably hundreds of objects in the Cloud eventually will be discovered that will meet Chuck's definition. Then it becomes rediculous to name the planets -- you'd be receiting all day. As far as Neptune is concerned, extraordinary evidence was involved in its discovery. It was the first planet to be found by something like our modern system of detecting extrasolar planets by the wobbling they cause in their stars. John Couch Adams, an English mathematician, predicted Neptune's existence because of the pull of its gravity on Uranus' orbit. He even calculated the probable position but the royal astronomer did not follow up quickly enough to discover Neptune. Meanwhile, a French mathematician, Urbain Leverrier, published a prediction of his own and got German astronomers to look for the planet -- and they quickly found it. Iinformation about it is available at this web site: http://www.u-net.com/ph/naw96/discover.htm. Interesting discussion -- Joe
--- Joe Bauman <bau@desnews.com> wrote:
The problem with allowing just anything in the Oort cloud into the planet club is that probably hundreds of objects in the Cloud eventually will be discovered that will meet Chuck's definition. Then it becomes rediculous to name the planets -- you'd be receiting all day.
Joe, who said you need to name them all? (Thousands of asteroids DO have proper names, BTW) Who said they need to be reciteable in one day? Why is it a problem to have hundreds of planets? Why do you personally need, apparently, to have a small planetary total? I don't fathom your logic on this. __________________________________ Do you Yahoo!? Win a $20,000 Career Makeover at Yahoo! HotJobs http://hotjobs.sweepstakes.yahoo.com/careermakeover
So, using this as argument, the method of discovery is important as to whether it's a planet or not? I still don't see where you are going. --- Joe Bauman <bau@desnews.com> wrote:
As far as Neptune is concerned, extraordinary evidence was involved in its discovery. It was the first planet to be found by something like our modern system of detecting extrasolar planets by the wobbling they cause in their stars. John Couch Adams, an English mathematician, predicted Neptune's existence because of the pull of its gravity on Uranus' orbit. He even calculated the probable position but the royal astronomer did not follow up quickly enough to discover Neptune. Meanwhile, a French mathematician, Urbain Leverrier, published a prediction of his own and got German astronomers to look for the planet -- and they quickly found it. Iinformation about it is available at this web site:
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I agree with Chuck's three planet criteria. But I also feel there really has to be a lower size limit. I just don't know where to put it. Patrick
participants (7)
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Brent Watson -
Chuck Hards -
David L Bennett -
Jim Cobb -
Jim Gibson -
Joe Bauman -
Patrick Wiggins