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No big planets close to the Sun?

  1. Feb 26, 2007 #1
    No big rocky planets?

    Why are there no big rocky planets - all the big planets are gaseous.
    Did big rocky planets get smashed up and end up in the Kuiper belt?
    Last edited: Feb 26, 2007
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  3. Feb 26, 2007 #2


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    There simply wasn't enough building material to make large rocky planets. Even if you put all the rocky bodies in the Solar System together, it wouldn't even come close to matching the mass of Jupiter.
  4. Feb 26, 2007 #3


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    Well, that plus if there weren't big gaseous planets, there'd be rocky ones in their places - all the giant gaseous planets are believed to have large rocky cores. So maybe a better question would be: why don't the rocky cores in the inner solar system have gaseous planets around them? The answer would be that it was blown away when the sun ignited.


    So, it is reasonable to assume that its fraction of heavier elements is also pretty close to the amount in the original primordial solar nebula.

    Here's what they think about the core:
    Last edited: Feb 26, 2007
  5. Feb 26, 2007 #4
    Jupiter and the gas planets started out at the size of earth originally, and when the sun blew out most of the nebula when it started nuclear fusion, the outer planets captured a lot of this gas, and thus, that is the reason why they are so big, and also, I believe that the nebula was mostly in the outer regions... I'll need to check up on that.

    The reason why some extrasolar planets are gas giants is because they are brown dwarfs, and never became stars, even though some are as much as 5 times bigger than Jupiter, and our instruments so far are not sensitive enough to find Earth sized planets.

    Btw, when is that telescope for finding Earth sized planets going to be launched?
  6. Feb 27, 2007 #5


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    Shouldn't the Sun have the largest and rockiest core of all?
  7. Feb 27, 2007 #6
    Umm, I'm not sure about that. "PSR B1257+12 A" is an exo-solar planet with a mass that is LESS than the earth's (it's only 2x lunar mass).

    But that's not all. A possible comet/asteroid may have also been discovered in the same pulsar system that has an UPPER mass limit of 0.0004 Earths!

    Exo-solar planets that are less than 8x Earth mass have also been discovered about main-sequence stars.

    There are several with similar mission statements. There was one launched in december, the French-led Corot mission.

    Then there are the James Webb Telescope, the Terrestrial Planet Finder (launch around 2015), or the Kepler mission (scheduled launch in October 2008).
    Last edited: Feb 27, 2007
  8. Feb 27, 2007 #7
    Why do you say that? I would think the intense temperature and pressure in the core would keep it in a gaseous state. Although the core does rotates as a solid body.
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