Explain why pluto has been demoted (no longer a planet)?
806256
The International Astronomical Union decided that Pluto was no longer a planet. The reason is that while Pluto is round, orbits the sun, and has three moons, it has not cleared (via gravity) its own orbit of debris.  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.
642503
Its a planet!!  On a serious note try this link\n\nhttp://en.wikipedia.org/wiki/Pluto\n\n:) Hope this helps........
2903
I quote : "Two small moons have been discovered orbiting Pluto, bringing the planet's retinue of known satellites to three and leaving scientist to wonder how it could be. ...The moons are catalogued as S/2005 P1 and S/2005 P2 for now. Once they are confirmed, the discoverers will suggest names, to be approved by the International Astronomical Union."\n\nFrom: http://www.space.com/scienceastronomy/051031_pluto_moons.html
1170805
Well that is a very good question, and one that is being debated as we speak. We now know that Pluto is much smaller than we previously thought (it is a very small planet and a moon) And we have now discovered a very large asteroid that some people want to call planet 10. In fact some people want to reclassify Pluto as they think it is too small to be called a planet.\n\nThe problem is that there is really no "exact" definition of what a planet is. I mean obviously a large body that orbits a star, is part of the definition. but when you get to smaller objects in irregular orbits, are they planets? planetoids? asteroids? something else?\nSo as for how large does an object have to be?\nwe will have to wait for the IAU (International Astronomical Union)\nto come up with a rigidly defined definition.\n\npersonally, I say an object that has enough mass to cause gravity to shape it into a sphere and has its own atmosphere should be called a planet. But hey that is just my personal opinion.\ncheck out these articles.\n\nhttp://news.bbc.co.uk/2/hi/science/nature/259767.stm\n\nhttp://www.space.com/scienceastronomy/planet_denitions_030227.html
894910
Good question \nPluto is out there somwhere after neptune . May be it is removed from the planet status but not from the solar system , It is in the status of a dwarf planet and it isn't lost and It isn't fair but this isn't the first  planet to be removed from the planet status but ceres was once aplanet in the ancient times it was in the planetery status for 5 decades and was removed by the same scientist/astronaut who found it , he stated he was wrong on his prediction and declared it was an asteroids which was floating the space which looked to him as a planet . It was said be in the middle of mars and jupiter .
487505
It's actually just a large asteroid, and they haven't decided whether to call it a planet yet. Problem is, they also discovered that Pluto is just a large asteroid, and if they disacknowledge the new planet, they would have to also disacknowledge Pluto.
570974
Are you talking about a real planet or Nibiru (aka Planet X)?  Note how I differentiate between the two.\n\nIf you're talking about a real planet (which I hope you are) it will probably depend on whether we end up changing how we define "planet" to accommodate new bodies that are being found beyond the orbit of Pluto.  If Pluto loses its planet status or new bodies are found, it would of course change which body is designated the "tenth planet."\n\nRegarding the 12th of December 2012, you'd probably be better off if you stopped paying so much attention to the Mayan calendar.  I doubt very much that anything of particular consequence is going to happen on that day, despite what New Agers are spouting nowadays.
716811
Its both ways actually-an asteroid and a planet.pluto circles the sun.this is the reason why its called a planet.but it also cuts across the eliptical orbit (if you know what i mean)while the others dont.There was a big debate on what pluto really was.anyway right now i think pluto is considered an asteroid and not a planet.
36045
You've been to Pluto? \nWhat's it like?\n\nThis is a nonproven theory:\nBecause when the Sun was forming, and condensing to it's present size, it spun faster and faster as it grew smaller. The first things to be spun off were rings of light gases that formed the outer gas planets. As it got hotter and smaller and faster, rings of heavier materials were flung off, creating the inner rocky and metallic planets. Pluto is technically a captured comet or other stray chunk, and probably came from further out in the system, perhaps a remnant of stars which previously exploded. We won't know until we get there.
567731
That's right because Pluto, in fact, may actually be an asteroid and not a planet at all.  It was thought for years that Pluto is a planet, and likely not formally *changed* persay, but it's the largest mass found in an asteroid belt, and, being spherical, it was assumed to be a planet.\n\nScience and the invention of things like the Hubble telescope have shown us more detail on such things as galaxies, planets, asteroid belts, etc.
984760
You'd have to contact an observatory to find out where it was in the sky in 11/98 but with an orbital period of 165 years, it hasn't moved far relative to us. Pluto, of course, is no longer considered a planet.
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.
735628
to pluto: meaning to relegate or to degrade or to jettison.\nMr. harris has been plutoed to overseas department.
761604
all i can say is that NOTHING HAS CHANGED. pluto is still a PLANET. a full blown, fully acceptable PLANET. it has its own moon (Charon) and therefore its own gravitational pull stong enough to attract and HOLD ON TO an object over half its own size and mass. show me any other "asteroid","stationary comet" or even another "planet" capable of such a feat. however, just because ASTRONOMERS deem pluto lesser than it is, has no effect what so ever on ASTROLOGERS exept to piss us off.
1043732
First of all, it is not galaxy you are talking about, it is solar system. Secondly, a lot of people here are saying why ask such a stupid question. What most of them probably don't know is that while pluto is the smallest of our "officially classified" planets it has come to light in recent months that we may have more planets. \n\nThe debate has been raging on in the space exploration community that recently discovered bodies past pluto may actually be planets in our system as well. They are also saying they may take pluto off the official planet list because it is looking more and more like a captured asteroid compared to these new planets.\n\nFor those who want to read more about these new planets, do a search for the planet Xena (which is the temporary code name for the new planet). \n\nIn short, Pluto is "currently" the right answer but if it is removed from the list, then mercury will be the smallest planet.\n\nHope this helps!
47426
No. There have been a number of objects discovered recently in the outer solar system, including one which appears to be larger than Pluto. But unless something about the size of Neptune is found (which is possible) none of these are likely to gain official planet status.\n\nIn fact, in many respects Pluto should be "demoted," although that is not going to happen.\n\nThere isn't a real scientific definition of where the boundry is between a planet and, say, a moon, or a Kuiper object. For most objects it's clear what to call them, but for others the classification is ambigious. The reason being, of course, that our classifications are (somewhat) arbitrary and the solar system is composed of a continuum of objects of different sizes, in different orbits, etc.\n\nPluto was called a planet when it was discovered because a 9th planet was expected. Percival Lowell spent a long time looking for such a planet which he predicted from orbital irregularities he calculated with Neptune and Uranus. But he never found what he was looking for. Clyde Tombaugh, a couple of years later, resumed the search and eventually discovered Pluto. However, Pluto is much too small and in the wrong place to be Lowell's suspected planet. Lowell was probably just wrong in his calculations.\n\nBecause a 9th planet was expected and because in 1930 little could be told of Pluto's physical characteristics, I don't think anyone seriously doubted whether or not it should be classified as a planet. It seemed obvious, at the time, that it was.\n\nIn the 1950s and 1960s astronmers began to postulate that comets orginated from a vast pool of objects in the extreme distant regions of the solar system. This lead to the hypothesis of the Oort cloud, and the "closer" Kuiper belt (that being 50 - 100 AU from the Sun).\n\nIt wasn't until the 1990s that a lot of Kuiper-esque objects were actually discovered. (I hedge on the classification, because some objects similar in diamter, etc., have been found inside the orbit of Pluto.)\n\nIf in 1930 Clyde Tombaugh had an inkling of something like a Kuiper belt he probably would not have assumed that Pluto was a planet. If Pluto was discovered today it also would (probably) not be considered a planet.\n\nSo basically, if we could re-do history Pluto would be "demoted." On the other hand, there have been generations of kids who learned the whole 9 planets bit. Because of the the International Astronomical Union - the international organization in charge of naming things - has *officially* declared Pluto a planet. A link to their announcement is below.\n\nI suspect - and I am taking an educated guess - that the new objects in the outer solar system, even though slighly larger than Pluto - won't get "official" planet status.\n\nOf course the reality is more complex, and nature doesn't always fit neatly into human classification schemes.
112225
The tenth planet is like really great, thanks for asking.  He spins around and around and makes one revolution around the sun about once every several thousand thousand years.  Therefore you might call this tenth planet (he doesn't mind) a chunk of ice, and not really planet-like at all.  But wait, you're saying, Pluto is a chunk of ice and also a planet!  Well, Pluto actually (he's telling me now) doesn't even consider himself a planet, as he's really just a large ice-chunk in the Kuiper Belt.  The tenth planet (we'll call him "Frank", that's what he prefers) is a little peeved that Pluto gets a thousand-brother belt to wear and all he's got is the occasional through-comet.  We can't help you, Frank, I'm sorry.  We're like, a billion miles away.