why isn't pluto a planet any more?
937727
http://en.wikipedia.org/wiki/Pluto\n\non 24 august 2006, the international astronomical union reclassified pluto.\n\npluto does orbit the sun, is ball-shaped and is not a satellite, but it does not have an isolated orbit (a bunch of other similar bodies have similar orbits.) so it is not a planet.\n\ni have been waiting for this since i was about ten when i learned that pluto didn't fit the pattern set by the major bodies in the solar system so it was an anomaly. it just felt "out of place". now that astronomers have found hundreds of other bodies with similar orbits, classifying "134340 pluto" as a planet is even more irrational. i feel somewhat satisfied, but i don't know how long this will drag on tho. many planetary astronomers are satisfied that the definition is rigorous enuf. i can accept that the definition is flawed, but i can not accept that "134340 pluto" is a planet.\n\nthis was the right thing to do, believe me. this does not change anything about pluto or the solar system. this just corrects the mistake of classifying pluto as a planet initially.\n\nthis same thing happened has happened before.  in 1800, an astronomer found a body orbiting between the orbits of mars and jupiter and thought it was a planet.  astronomers finally stopped classifying them as planets after they found several other bodies with similar orbits, and no one thinks ceres, pallas, juno, and vesta are planets today.\n\nmany astronomers consider pluto and charon to be a binary system, but two small bodies orbit that system. they are called nix and hydra.\n\nincidentally, "134340 pluto" was never a moon of neptune. neptune did capture triton. this is why triton has a retrograde orbit
785248
http://en.wikipedia.org/wiki/Pluto\nhttp://www.iau.org/fileadmin/content/pdfs/Resolution_GA26-5-6.pdf\n\non 24 august 2006, the international astronomical union reclassified pluto.\n\npluto does orbit the sun, is ball-shaped and is not a satellite, but it does not have an isolated orbit (a bunch of other similar bodies have similar orbits.) so it is not a planet.\n\ni have been waiting for this since i was about ten when i learned that pluto didn't fit the pattern set by the major bodies in the solar system so it was an anomaly. it just felt "out of place". now that astronomers have found hundreds of other bodies with similar orbits, classifying "134340 pluto" as a planet is even more irrational. i feel somewhat satisfied, but i don't know how long this will drag on tho. many planetary astronomers are satisfied that the definition is rigorous enuf. i can accept that the definition is flawed, but i can not accept that "134340 pluto" is a planet.\n\nthis was the right thing to do, believe me. this does not change anything about pluto or the solar system. this just corrects the mistake of classifying pluto as a planet initially.\n\nthis same thing happened has happened before.  in 1800, an astronomer found a body orbiting the sun between the orbits of mars and jupiter and thought it was a planet.  astronomers finally stopped classifying them as planets after they found several other bodies with similar orbits, and no one thinks ceres, pallas, juno, and vesta are planets today.\n\nmany astronomers consider pluto and charon to be a binary system, but two small bodies orbit that system. they are called nix and hydra.\n\nincidentally, "134340 pluto" was never a moon of neptune. neptune did capture triton. this is why triton has a retrograde orbit
425085
Pluto - 1930.\n\nPluto is still considered a planet and all the objects that Mike Brown et.al. have been finding (Sedna, 2003UB313, etc.) have not been granted planetary status, no matter how often Mike Brown says that 2003UB313 is a planet, quite simply it is not.\n\nThe IAU's Division of Planetary Science is currently working on the whole planet issue, and we are supposed to have some sort of resolution to this issue by august of this year.  Right now it seems that we are leaning to either strip Pluto of its planetary status, through making an actually definition of the word "planet," or to make Pluto the arbitrary cut-off line.  This would mean that 2003UB313 would become the 10th planet, but Sedna (being smaller than Pluto) would not.\n\nAs of right now there is no official motion in place to remove planetary status from pluto, although it may loose it through the adoption of a new definition of what a planet is.\n\nAlso, no matter how catchy the name sounds, or how often the BBC calls it that, the official name of 2003UB313 will not be "Xena," that was simply Brown's code name for that object.
45656
Designated 2003 UB313 (it hasn’t been officially named yet), this “planet” is slightly larger than Pluto, has a small moon and takes more than 500 Earth years to orbit the Sun.\nA planet is a body large enough that, when it formed, it condensed under its own gravity to be shaped like a sphere. It orbits a star directly and is not a moon of another planet.\n To simplify things, some scientists propose that the size of Pluto be designated the smallest size for a planet. If that argument carries the day, we now have 10 planets, since 2003 UB313 meets all the criteria.
352109
Actually, the people who found it honestly want to have it called Xena.\n\nOn July 29, 2005, a Trans-Neptunian object called 2003 UB313 was announced, which on the basis of its magnitude and simple albedo considerations is assumed to be larger than Pluto. This caused its discoverers to call it the "10th planet" of the solar system, although there is no consensus yet on whether to call it a planet, and others consider the new discovery to be the strongest argument yet for demoting Pluto to the status of a minor planet.\n\nBut until then, it's being refered to as Planet X.
161091
well, scientists are redefining the word "planet", so pluto might get excluded as a planet, and we might have only 8, or if pluto is a planet, 8 other bodies will be planets. so there could be 17 planets
15622
In the last few years, there have been three bodies each reported as being a new tenth planet. Their provisional names are: 50000 Quaoar, 90377 Sedna and 2003 UB313.\n\nEach time a new planetoid discovery is named, it reignites discussion on whether Pluto itself, currently considered the solar system's ninth planet, is truly a planet at all.\n\nIn fiction, tenth planets are quite common: one of the most famous was created for the British television science fiction series, Doctor Who, in 1966. In that story, the tenth planet was Mondas, originally a sister planet to Earth, which somehow left our solar system for a while. To survive, the humans on the planet started replacing their body parts with cybernetics -- over time turning the whole planet's population into Cybermen.
406851
In our Solar System?  Unlikely.  There are a bunch of things orbiting beyond Pluto that are bigger than it that could be considered planets if size were everything... although Pluto is just a large Comet that orbits on the inside of the Oort cloud.  \n\nIf there was anything beyond Neptune of any consequential size, chances are we would have detected it by now.
767889
The International Astronomical Union decided that Pluto was no longer a planet.  Instead, they decided to classify it as a "dwarf planet".\n\nSee the details below.\n\nRESOLUTION 5A\nThe IAU therefore resolves that "planets" and other bodies in our Solar System, except satellites, be defined into three distinct categories in the following way:\n\n(1) A "planet" [footnote 1] is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.\n\n(2) A "dwarf planet" is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape [footnote 2] , (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.\n\n(3) All other objects [footnote 3] except satellites orbiting the Sun shall be referred to collectively as "Small Solar-System Bodies".\n\n\nFootnote 1: The eight "planets" are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.\n\nFootnote 2: An IAU process will be established to assign borderline objects into either dwarf planet and other categories.\n\nFootnote 3: These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies.\n\nRESOLUTION 6A\nThe IAU further resolves:\n\nPluto is a "dwarf planet" by the above definition and is recognized as the prototype of a new category of trans-Neptunian objects.
7411
You have to understand that as telescopic and computing power increase, we will be finding tons of new "planets" in the solar system.  Most people agree, that Neptune is the last "true"  planet in the solar system.  Pluto is likely just an object in the Kuiper Belt, an area on the outskirts of the Solar System, where the Sun's influence dwindles rapidly and there are tons of rocks floating around.  Pluto has a minor atmosphere and a moon, Charon.  There is a debate that starts up every time a new large object is found around where Pluto is, this happens every few years.  Bottom line: there probably won't be any more planets added to the roster, and Pluto won't lose its planetary status...there is just too much involved in changing things.  So, to answer your question, Poseidon probably exists, but its probably not going to be a planet.
373101
There is debate over whether Pluto should even be classified as a planet.  It seems out of place with the gas giants of the outer solar system beyond the rock belt.  Also, other similar bodies are being found beyond Pluto that are not being made "planets".  Finally, Pluto has a satellite, or "moon", Charon, which is actually almost as big as Pluto istelf, and orbits very, very close to Pluto.  From Earth, they barely resolve (depending on the quality of the instrument) and appear joined at the hip as it were.  Pluto takes 248 years to orbit the sun.  Since it was discovered in 1930, man has not even observed one of its completed orbits around the sun.  Pluto follows an extremely exaggerated elliptical orbit, which actually crosses paths with the orbit of Neptune.  Thus, sometimes Neptune is the furthest planet from the sun, other times it is Pluto.\n\nUranus rotates about its own axis which is "sideways" (a relative term), at 98 degrees tilt.\n\nNeptune has a Great Dark Spot, which is a storm similar to the Great Red Spot of Jupiter.
825827
read http://en.wikipedia.org/wiki/Pluto\n\npluto is neither a planet nor a comet.\n\npluto does orbit the sun, is ball-shaped, does not have an isolated orbit (a bunch of other similar bodies have similar orbits.), and is not a satellite so it is not a planet.\n\ni have been waiting for this since i was about ten.  i knew that pluto didn't fit the pattern set by the major bodies in the solar system so it was an anomaly.  it just felt "out of place".  now that astronomers have found hundreds of other bodies with similar orbits, classifying "134340 pluto" as a planet is even more irrational.  i feel somewhat satisfied, but i don't know how long this will drag on tho.  this was the right thing to do, believe me.  this does not change anything about pluto or the solar system.  this just corrects the mistake of classifying pluto as a planet initially.\n\nmany astronomers consider pluto and charon to be a binary system, but two small bodies orbit that system.  they are called nix and hydra.\n\nincidentally, "134340 pluto" was never a moon of neptune.  neptune did capture triton. this is why triton has a retrograde orbit.
57853
Actually there is no tenth planet. Although Pluto is an official planet, others objects of about the same size, or even slightly larger won't be officially recognized as planets.\n\nAn object would need to be much larger, say the size of Neptune to become and official 10th planet. And some astronomers think that should an object may be out there.
1178690
Right now the international convention in astronomy is debating on how a planet is defined... Pluto appears to be just one of the thousands of objects in the Kuiper belt which is believed to contain objects more massive than Pluto, 2003 ub313 is one prime example and is classified as a Trans-Neptunian object... I have already debated this topic with all the other webdatedotcom friends I have and the arguments are pretty interesting..
945846
This issue is very similar to the asteroid belt issue some 150 years ago.  When the first asteroid, Ceres, was found, it was considered a planet.  Only after 15 other "planets" were found in the same orbit regime did astronomers downgrade these asteroids to "minor planets" some 50 years after Ceres' discovery.\n\nIt's unclear if Pluto could ever clear its orbit...it crrently has only 7% of the mass of its orbital neighborhood (as opposed to, say, Earth, which contains some 99.9999% the mass of its orbital neighborhood), so it's only cleared a tiny fraction of its orbit throughout the entire age of the Solar System, 4.5 billion years.\n\nMoreover, other objects in Pluto's orbit (and pluto itself, in fact) are trapped in a 3:2 orbital resonance with Neptune.  This means these "plutinos" are in a very stable orbit, unlikely to be scattered away unless something very big and unexpected comes along.
120883
The newest planet was catalogued as 2003UB313 by NASA.\n\nThe new planet, which is yet to be formally named, is at least as big as Pluto and about three times farther away from the Sun than Pluto. It is very cold and dark. The planet was discovered by the Samuel Oschin Telescope at the Palomar Observatory near San Diego, Calif., on Jan. 8, 2005.
23405
There are still 9 according to the latests NASA reports. Although it has been found that there are several other small objects orbiting past Neptune that are similar in make up and size to Pluto- that pluto's categorization of planet will not be changed. That instead a number system is being talked about to go into effect that will number the bundles of pluto-like objects. Though again, pluto would not be changed. (First Source)\n\nIf it weren't for the stubborn desire to keep tradition- Pluto WOULD NOT be considered a planet, it just does not have the characteristics to make it one. But because tradition is very important in this society- Pluto remains a planet for now.