Pluto defines a Planet as being a Planet!

[Saiph]

As I've pointed out elsewhere on the boards, there is an analytical method to quantify how influencial an object is in it's orbit/neighborhood. Check Wikipedia for a brief discussion of one such technique. <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>

 

[wonky]

I have no problem with the "dwarf planet" designation. I highly doubt Pluto will be ejected from all textbooks now.<br /><br />You can be assured that the definition of planet will be debated for years, decades, who knows, maybe even centuries to come.<br /><br />Jake, why are you so in love with Pluto, anyway?

 

[adman69]

I posted this at another thread but it fits here also...I respectfully enter the following statement for thought here also...<br /><br />For God's sake everyone...why can't everyone understand that Pluto has been a planet since it's discovery...who cares if it was an accident, or if it is like a hundred different objects in it's vicinity? It still marked an acheivement in science for it's time. We never thought it possible at the turn of the century to find something that far out...but Tombaugh did. It's historical significance alone should preserve it's identity as a planet. For once science doesn't have to be a kill joy. Why should Pluto suffer just because we've advanced technologically? I really believe science and sentimentallity can co-exist just this once. Uniqueness, mass, cleared zones, satellites or similarities don't have to mean squat. Just because man has advanced doesn't mean we can't still marvel at our past accomplishments. Demoting Pluto to me is like disavowing a great discovery and acheivement of our species.

 

[jaxtraw]

I wouldn't trust somebody to tell the difference between a planet and a dwarf planet if they can't tell the difference between Percival Lowell and Clyde Tombaugh <img src="/images/icons/wink.gif" />

 

[wonky]

The logic that "Pluto has always been a planet so it should remain so" makes no sense. Since antiquity to only a few hundred years ago, the sun and moon were considered to be planets. Should we re-instate them, too?

 

[jakethesnake]

Hey Wonky read what I wrote! I did not say "Pluto has always been a planet so it should remain so".<br /><br />This is what I wrote:<br /><br />I would suggest that with something such as Pluto holding its sentimental status for 76 years during which time we have been to the moon and back several times and have had a space telescope “Hubble” in orbit since 1989 that someone i.e. the IAU could have come up with something more definitive than a planet clearing its “neighbourhood”! We could scientifically surmise that we are now left with specific gravity to determine weather a planet is a planet by which it is able to become spherical by its own mass but, no that doesn’t work either because that is also what classifies a “dwarf planet” on the lower end of mass.<br /><br />Wonky what scientifically differentiates a “Dwarf Planet” from a “Planet”?<br /><br />The answer is “NOTHING AT ALL” except that a classification was come up with to limit the planet count in our solar system and nothing to do with science at all!<br /><br />According to the IAU when a celestial body has enough mass to clear its neighbourhood then it is a planet so I would like you to tell me what amount of mass that is?<br /><br />The answer is you can’t tell me and neither can the IAU and is that science?<br /><br />We don’t even know how many NEO’s there are in our own planet’s neighbourhood so, how can we possibly know if a planet has cleared any neighbourhood”?<br /><br />I reinterate:<br /><br />We don’t know what the upper mass limit is in which a planet becomes a “Brown dwarf” and, the only lower mass limit that can be used scientifically to limit weather a planet is a planet is the lower mass limit in which a celestial body becomes spherical but that’s what defines a “dwarf planet” What a bunch of CRAP!!!<br /><br />To turn this back on you Wonky I would say you can’t just declassify Pluto as a planet because there might be more planets that size in our solar system. I would say that makes no sense.<br /> <div class="Discussion_UserSignature"> <strong></strong> </div>

 

[kheider]

<blockquote><font class="small">In reply to:</font><hr /><p>you can’t just declassify Pluto as a planet because there might be more planets that size in our solar system.<p><hr /></p></p></blockquote><br /><br />But if there are close to 100 Pluto-sized KBOs, then yes, we need to seriously consider classifying them as separate (ie: not as a subcategory) from the Major 8 Planets. From the evidence already available we have a good 50 contenders for Dwarf Planets.<br /><br />As for what makes a planet, I assume that you have read Soter's artcile What makes a Planet.<br /><br />In the future we will decide if 'Dwarf Planets' should be known as a subcategory of Planets or if they should be a separate category such as Planetoids. For now, 'Dwarf Planets' are not Planets.<br /><br />-- Kevin Heider

 

[alokmohan]

Percival Lowell died before pluto was discovered.Did he mean Clyde Tombaugh?Is true Clyde Tombagh died few years back.

 

[alokmohan]

http://www.sciencenews.org/articles/20060902/fob6.asp

 

[alokmohan]

Percival Lowell died before dicovery of pluto.A wrong impression has been give that pluto renamed after death of Lowell.

 

[wonky]

Jakethesnake, I wasn't attributing that quote to you, I just meant the argument in general. Personally I don't agree with the definition of planet, especially since it hinges on clearing the neighborhood--that's what differentiates planets and dwarf planets--not even size or mass! I have no problem with the dwarf planet category but the definitions need to be tweaked. <br /><br />Like someone else said, it doesn't make sense for Pluto to be classed with the classical planets if we eventually discover 100 more similar sized KBO's out there.<br /><br />There was a similar situation with the asteroids, you know. The first four to be discovered (Ceres, Vesta, Pallas, Juno) were listed as planets for 50 years, even in elementary school text books! But once more and more asteroids were discovered, they were reclassified. I wonder if anyone was screaming about it back then? I think many astronomers of the day continued to count them as planets, and this continued till the next generation took over.<br /><br />Of course lately, since Ceres has been discovered to be nearly round, have a differentiated interior, the possibility of a thin atmopshere, Ceres's classification as an asteroid has come into question.

 

[jakethesnake]

Right now there is only one celestial body that is of greater size than Pluto and that is UB313 or informally known as Xena. We have had the Hubble Space telescope in orbit since 1989 and, a whole host of very large Earth based telescopes built so, the question I have is where are these hundreds of “similar sized objects”?<br /><br />When referring to the different classifications of stars we either refer to them as being in a certain stage of development such as a “Red giant” or quantify them as having a specific mass and refer to them as having so many solar masses due to what happens to them after they go nova. Comets and asteroids are different due to their composition.<br /><br />So tell me what differentiates a “Dwarf Planet” from a “Planet” other than a planet is “clearing its neighbourhood”?<br /> <div class="Discussion_UserSignature"> <strong></strong> </div>

 

[kheider]

>Right now there is only one celestial body that is of<br /> />greater size than Pluto and that is UB313<br /><br />Actually Triton is 2700km in diameter and <b>almost twice the mass of Pluto</b>. Since Triton orbits Neptune backwards, it is most likely a captured KBO.<br /><br /> />where are these hundreds of “similar sized objects”?<br /><br />They would mostly be in the Kuiper belt. Some would be scattered from the Kuiper Belt. Scientific progress is actually a rather slow process. Keep in mind that not that many people are actively searching for KBOs, and it can take months of observations to confirm an orbit. The albedo of some of these objects is going to be rather low. Xena stuck out more easily because it has a very high albedo.<br /><br />And I would say a 'similar sized object' would be from 500km (Dwarf Planet contender) to 3000km in diameter. It is interesting to note that there are currently no (non-captured KBOs) moons in the solar system between 2000-3000KM in diameter! Europa is 3138km in diameter and 3.7x more massive then Pluto.<br /><br />The fact we have two KBOs (Triton + Xena) already larger than Pluto is exciting. Do you want a preview of what Pluto will look like? Look at a picture of Triton. Pluto will very likely just be smaller. <img src="/images/icons/wink.gif" /><br /><br />-- Kevin Heider

 

[derekmcd]

<i> and to quote the NASA guy in Armageddon, "Pardon me, Mr. President, but it's a big --- sky!"</i><br /><br />That exchange was the best part of that movie. <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[mikeemmert]

<blockquote><font class="small">In reply to:</font><hr /><p>Actually Triton is 2700km in diameter and almost twice the mass of Pluto. Since Triton orbits Neptune backwards, it is most likely a captured KBO. <p><hr /></p></p></blockquote>Here's something interesting I have noticed about that. Where are Neptune's original moons? Proteus and the other small ones are most likely original moons of Neptune, but where are the four "Galilean" satellites?<br /><br />The Sun has four gas giants; Jupiter has four large moons; and Uranus also has four large moons. Saturn has four moons of similar size, Tethys, Dionne, Rhea, and Iapetus, but they're overshadowed by Titan. I think Titan is a captured body too with a similar origin to Triton.<br /><br />I did some GravitySimulations of the capture of Triton. To add realism, I created four faux moons for Neptune by copying Uranus' moons onto Neptune. Of course, I looked at the mass of Uranus' moons and copied that over, too.<br /><br />Here's an interesting offshoot of that project: if you add the mass of Uranus' moons to Pluto, the total is just about the same as the mass of Triton!<br /><br />It's significant that Pluto is bigger than the combined total of Uranus's moons. If it was the other way around, the whole mess would probably have dropped into Neptune, since their rotation (orbital motion) would have cancelled each other.<br /><br />The upshot of all this is that it seems likely that Pluto, Xena, and Triton all started out the same size. I think they all formed in the Sun/Neptune Lagrange points L4 and L5 as a pair of binaries.<br /><br />So that makes four objects. Where is the other one?<br /><br />I think it's 2003 EL61,nicknamed "Santa", one of the strangest objects in the Solar system. It is about 30% the mass of Pluto. But it is made almost entirely out of rock, with a thin glaze of ice. It has a very rapid spin, turning on it's axis once every 3.9 hours. Th

 

[cuddlyrocket]

Here's a (moderately lengthy) view of what went on at the IAU meeting from a participant, together with some comments on the 'Pluto petition', as reported on the Bad Astronomy board.

 

[jakethesnake]

Thanks to (CuddlyRocket) for providing this link. This is a very interesting inside look at how the IAU works and, shows exactly how Pluto was demoted. <br /><br />What was held in Prague was a General Assembly of the International Astronomical Union (IAU) and, the intent of these General Assemblies are to decide on specific arbitrary definitions that allow astronomers to talk to one another across language barriers enabling the world’s various science communities to interpret each others data.<br /><br />The IAU as described by the individual at this link “Guy J. Consolmagno” is a member of the American Astronomical Society, Division for Planetary Science. He explains how the IAU is broken into various committees. The committee responsible for Pluto’s demotion was referred to as the IAU’s Division III (the planetary scientist’s corner of the IAU).<br /><br />Here is how he describes what was going on in Prague:<br /><br />-----------------------------------------------------------------------<br /><br />General Assemblies are different from typical scientific congresses. Rather than being focused exclusively on presenting scientific results, the main point is to decide on all the arbitrary but necessary definitions that let us talk to each other and understand each other's data. For example, were worrying about tweaking the definition of latitude and longitude on the Moon to match the expected precision of the coming generation of lunar spacecraft from India, China, Japan, and the US.<br /><br />Likewise, defining what is a planet is both arbitrary and necessary. How do we name the newly discovered objects out beyond Pluto, that rival Pluto in size? (The rules, and the committees, for planets are different than those for comets and asteroids.) Which committee keeps track of their orbits, and assigns names to their surface features? What definition works for planets around other stars?<br /><br />-----------------------------------------------------------------------<br /><br />O <div class="Discussion_UserSignature"> <strong></strong> </div>

 

[jakethesnake]

What amount of mass does a celestial body need to clear its neighbourhood?<br /><br />What scientifically differentiates a “Dwarf Planet” from a “Planet” other than a celestial body must have to clear its neighbourhood?<br /><br />What is the upper mass limit is in which a planet becomes a “Brown dwarf”?<br /><br />You can’t just declassify Pluto as a planet because there might be more planets that size in our solar system.<br /> <div class="Discussion_UserSignature"> <strong></strong> </div>

 

[wonky]

That's the problem, Jake. The definition certainly needs to be modified. If the only difference is clearing the neighborhood, then if a body the size of Earth (or larger!) were discovered in the Kupier belt, it would be considered a dwarf planet according to that definition.<br /><br />The way I see it, the general public will always see Pluto as a planet, no matter what. Astronomy sites are alerady listing the dwarf planets alongside the "real" ones so Pluto will not be forgotten--nor will the arguement as to whether it's a "real" planet or not.

 

[wonky]

Here's a funny interview with Pluto.<br /><br />http://www.brunching.com/morepluto.html

 

[jakethesnake]

Hey Wonky, it’s actually pretty funny and I get your point. By the way Pluto sounds scarily like my Ex! <div class="Discussion_UserSignature"> <strong></strong> </div>

 

[MeteorWayne]

Great Wonky. Thanx <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[jakethesnake]

2003 UB313 is the only "Dwarf Planet" larger than Pluto so, that’s not hundreds or even dozens. It seems to me and many others that at this point as long as the IAU is using an arbitrary cutoff for what differentiates a “Dwarf Planet” from a “Planet” then Pluto would be as good a place to start that cutoff as any. <div class="Discussion_UserSignature"> <strong></strong> </div>

 

[alokmohan]

Cut off point is arbitrary.But we have to stick to something now.Will you say logically jupter and mercury are colleages?No .But traditon and precedence dictates.What I dont understand is why this debate about pluto?In science such type of political debate is unusual.Poor Lowell .What they have done?How Mrs Tombaugh comes into picture?

 

[adman69]

I can agree that the universe as we know it will from this point on change almost weekly. The upsetting part of this is that Pluto defines a technological milestone in history and for that reason alone it should be allowed to keep it's status. Surely science could coexist just this once with history and the very magic that astronomical milestones have given us for centuries. Pluto is a planet-dwarf or not-and to change that now just based on mass or orbit takes something away from the discovery of Tombaugh and all that preceded and followed in his footsteps.