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Twelve Planets

  1. Aug 16, 2006 #1

    BobG

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    The International Astronomical Union is about to decide the Solar System has 12 planets. The new planets:

    Xena would become the most distant planet.

    Charon would become a planet. Since Pluto and Charon both orbit a point in space outside of both, Pluto and Charon become a double planet system.

    Ceres, the first and largest asteroid discovered, becomes the solar system's smallest planet. Actually, when Ceres was first discovered, it was classified as a planet and was later downgraded to asteroid status.

    http://news.yahoo.com/s/space/20060816/sc_space/nineplanetsbecome12withcontroversialnewdefinition [Broken]

    Don't expect the number to remain at 12 very long. The number of planets in the solar system will jump to anywhere from 24 to 53 fairly quickly, with the number eventually rising into the hundreds or thousands.

    The new definition is pretty simple: "A planet is a celestial body that (a) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (b) is in orbit around a star, and is neither a star nor a satellite of a planet." (Charon isn't a satellite of Pluto since the two orbit a point in space outside of both objects).
     
    Last edited by a moderator: May 2, 2017
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  3. Aug 16, 2006 #2

    Danger

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    I had enough trouble trying to remember the ones that we already have. :grumpy:
    It would have been a lot easier if they'd just downgraded Pluto.
     
  4. Aug 16, 2006 #3

    Astronuc

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    Last edited: Aug 16, 2006
  5. Aug 16, 2006 #4

    Gokul43201

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    Does it then lose the "1" prefix?

    I'm not sure whether Ceres will feel like she's being upgraded or downgraded.
     
  6. Aug 16, 2006 #5
    http://www.space.com/scienceastronomy/060816_planet_resolution.html
    "plutons". :rofl:
     
  7. Aug 16, 2006 #6
    Not Xena yet, right now it's 2003 UB313.
     
  8. Aug 16, 2006 #7

    JasonRox

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    Sounds like Astronomers are desparate for attention.
     
  9. Aug 16, 2006 #8

    Chi Meson

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    A good point. Seems to be a long season between comets.
     
  10. Aug 16, 2006 #9

    Astronuc

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    I seem to remember a term "planetoids", which was probably 35+ years ago. I was wondering what happened to the usage.

    I found this on Wikipedia - http://en.wikipedia.org/wiki/Minor_planet

    Of course, the singificance of recent events means that Ceres and some other objects may have their designations changed.
     
  11. Aug 16, 2006 #10
  12. Aug 16, 2006 #11
    I kind of like calling just 2003 UB 313. Kind sounds cool and it's differn't then naming after a roman god.
     
    Last edited: Aug 17, 2006
  13. Aug 16, 2006 #12

    SpaceTiger

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    I don't really care how they classify them, I'm just happy to see them finally putting together a self-consistent scheme. It should have been done long ago, IMO.
     
  14. Aug 16, 2006 #13

    DaveC426913

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    Cuz you gotta hate those roman goods. :biggrin:
     
  15. Aug 16, 2006 #14

    DaveC426913

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    Oh MAN this is going to mess up all those Astrologers...
     
  16. Aug 16, 2006 #15
    They seemed to adapt quite nicely to Pluto's addition...and that was less than 80 years ago...
     
  17. Aug 16, 2006 #16
    Xena, is that the Keiper object that's out in The Ort Cloud? I don't think Ceres should be a planet. Is it round?
     
  18. Aug 17, 2006 #17

    Gokul43201

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    Very well rounded - an excellent candidate! :approve:
     
  19. Aug 17, 2006 #18

    Phobos

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    "plutons"...now is that pronounced "plu-tons" (as it looks) or "plu-tones" (to better match "Pluto")?

    "Downgrading" Pluto may be easier (I'll never memorize the eventual dozens/hundreds/whatever of planets), but adding planets may be more exciting/positive for the general public ("this just in...new planet discovered!") and may better promote science education. Heck, even astronomers may find it more fun even if they know its just semantics. But like SpaceTiger said, it's good to have some tighter definitions (even considering http://www.badastronomy.com/bablog/2006/08/15/congratulations-its-a-planet/")
     
    Last edited by a moderator: Apr 22, 2017
  20. Aug 17, 2006 #19
    I've done the math for when the Earth-moon barycenter will be outside of the planet, and I get substantially different results...

    Distance to barycenter: M_Moon / (M_Earth + M_moon) * new_distance

    Set this equal to the Earth's radius, we have:
    .0122 * new_distance = 6378km =>
    new_distance = 524000km

    distance_traveled = new_distance - current_distance = 524000km - 385000km = 139000km.

    Time to travel distance = (139000km) / (4 cm/yr) = 3.48 BILLION years.

    This guy simply divided the distance of the barycenter from the surface by the rate of travel, which is NOT correct.
     
    Last edited by a moderator: Apr 22, 2017
  21. Aug 22, 2006 #20

    Phobos

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  22. Aug 23, 2006 #21

    Astronuc

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    To be or not to be . . . a planet? That is the question.

    Pluto's Planetary Status Teeters -- Again
    http://www.npr.org/templates/story/story.php?storyId=5691890
     
  23. Aug 23, 2006 #22
    From what I've been reading, I wouldn't be surprised that we come out of this meeting with no planet definition at all:

    "The vote is a "yes" or "no" proposition, so it is possible that the meeting will end with no planet definition." [http://www.space.com/scienceastronomy/060823_planet_vote.html" [Broken]]

    It's a shame, too...I liked the proposal first proposal quite a bit (the one that would have added Charon/Ceres/Xena).
     
    Last edited by a moderator: May 2, 2017
  24. Aug 23, 2006 #23
    I say we downgrade pluto, this adding of Xena Ceres and Charon are rediculous, and aparently there are 20+ other candidates. So we're going to have 30 planets now? I especially think Charon and Ceres were mistakes in adding because uptil now Charon was classified as a moon but because of it's unusual orbit around pluto it is now a planet. And Ceres is a freakin' asteroid.
     
  25. Aug 23, 2006 #24
    I never understood the aversion to more than ~10 planets in the solar system. So what?

    Ceres might be a little TOO small...I think they should wait until they can get a better look and truly determine if its in hydrostatic equilibrium. If it is, I have no problem with it becoming a planet.

    The barycenter definition seems to be the only concrete way to distinguish a double planet from a planet-moon system. I think all the other methods are very arbitrary.

    I think the problem is that people have it in their heads that all planets must be larger than all moons, and I really don't believe that this should be the case.
     
  26. Aug 23, 2006 #25
    I think they would just like to see it based on some meaningful definition of what a planet is – not just how many can we add to the count.
    Maybe two general categories;
    1)Large rocky inner planets found in near circular orbits around their sun and
    2)Much Larger Gas giants also in near circular orbits but usually expected much outside the area of the rocky planets.
    Now a solar system should be expected to have rocky asteroids and dirty snowball chunk of ice comets, but should we call large ones of those planets just to satisfy adding a few more names to be honored as discoverers.

    Frankly if an American had found one of the first 8 instead of the ninth, I suspect Pluto would have been down graded some time ago.
    It shouldn’t stay on (or come off) the list because of politics.
    And if it does come off – it is just as easy to say “SO WHAT” if the categorization makes better sense why not.
     
    Last edited: Aug 24, 2006
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