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I Resemblances between moon surface and earth mantle

  1. Nov 13, 2017 #1
    The Theia hypothesis is the current leading hypothesis to explain how our moon was created. Both earth's mantle and the moon's surface have indistinguishable oxygen isotope ratios, which leaves the earth–moon system as more similar in O isotopes than any other two bodies in the solar system

    However, new research suggests that the earth's mantle (mostly olivine) doesn't resemble the moon's surface (also olivine, but mostly orthopyroxene) as much as we thought.

    Does this change our view on the Theia hypothesis?

    Sub question: were others moons (for instance the Galilean moons) also created partly with material of their host planet?
  2. jcsd
  3. Nov 13, 2017 #2


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    That's right.
    I have been recently reading about this in a book called "Calculating the Cosmos" by Ian Stewart and in a chapter he discussed the formation of the Moon.
    In my opinion this article and research by the team could potentially change the current view on the formation of the Moon, as you said, true.
    Colliding with the side of Earth and not full-on, Theia must have splashed a lot of the Earth core's material into space which then mixed with everything left from Theia to form the Moon.
    However what this interesting article states is that there is not much of Earth's core's material in the Moon, but more of orthopyroxene that lacks in the Earth's core, which contradicts the Theia theory.
    I think we must wait and see what will happen in the future with this research and the team to reason further.
    Don't you think?

    Most likely.
  4. Nov 13, 2017 #3
    My limited understanding tf this 'giant impact theory' is that the narrative ascribes the impactor to have a mass comparable to Mars which is about 12% MEarth. Stewart (in the excellent book you mention) describes the Earth being "ABOUT 10%" smaller.

    Obviously, the moon has only a fraction of this mass (another factor of 10), which suggests to me that the vast majority of "theia" or whatever must have been agglomerated or whatever the process is called along with the other composition pieces that formed the earth - only a tiny splinter remains as the moon.
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