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Quick formation of our moon?

  1. Jan 12, 2016 #1
    From what I've seen on shows like how the universe works and the Wikipedia article on Theia, they are saying that the moon was formed in less than a year after the impact.
    My question is, how did that happen so quickly?

    I am simply a fan of watching shows like that or reading articles about space. I have no degree or schooling related to this field, but I do find it quite fascinating!

    Thank you in advance.
  2. jcsd
  3. Jan 12, 2016 #2
    There are other plausible explanations for the existence of our Moon, but this idea of collision of protoplanets does fit well with what evidence exists, (Moon rocks largely)
    I took a look at the wiki article and nothing is stated there about how long the Moon took to form following such a collision.
    My intuition agrees with yours though, that less than a year for the debris to assemble into what now is our Moon seems unlikely.
  4. Jan 12, 2016 #3
    Ok. I was reading this article:


    This one actually says it could have formed in less than a month!

    However, I first heard this in an episode of how the universe works. In that episode, they state that it could have formed in less than a year.
  5. Jan 12, 2016 #4


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  6. Jan 12, 2016 #5
    Unfortunately that page won't load on my phone, so I will have to check it out when I have a chance to dust off and boot up the old laptop. Thank you though!

    I have another question regarding accretion and gravity now that I'm thinking about it. Not sure if I should start a new thread though.

    What prevents items from either the Kuiper Belt or the Oort cloud from forming larger bodies? The shows make it sound like these structures are leftovers from the formation of our planetary bodies and are doomed to be alone.
  7. Jan 12, 2016 #6


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    The same paper also discusses the energetic aftermath hypothesis where the proto-lunar disc would have endured for about a century. It is, however, true that accretion can progress fairly rapidly. We know, for example, the planets of the solar system are approximately the same age as the sun. It is safe to assume the accretion rate had to be pretty high to assemble some of the larger planets in such a short time frame. KB and Oort cloud objects are very widely dispersed so gravitational accretion would be strongly inhibited. The abundance of matter within the planetary orbits was obviously much greater facilitating more efficient gravitational accretion.
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