Difference between revisions of "Origin of the Moon"
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| − | + | Various theories regarding the origin of the moon have been considered as follows:<ref>http://www.psi.edu/projects/moon/moon.html</ref> | |
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# One theory was that the Moon formed in an orbit around Earth, at the same time that Earth formed. But the lack of iron on the Moon, in contrast with the abundance of iron on Earth, disproved this. | # One theory was that the Moon formed in an orbit around Earth, at the same time that Earth formed. But the lack of iron on the Moon, in contrast with the abundance of iron on Earth, disproved this. | ||
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# Yet another theory was that the Earth spun off the Moon. This solves the isotopic similarity, but an analysis of the total angular momentum and energy involved shows that this is impossible in light of the current orbit. Also, spinning of the Moon would have given it iron also. | # Yet another theory was that the Earth spun off the Moon. This solves the isotopic similarity, but an analysis of the total angular momentum and energy involved shows that this is impossible in light of the current orbit. Also, spinning of the Moon would have given it iron also. | ||
| − | + | # The final theory, now generially accepted, is that that impact with a large planetesimal released a great quantity of debree into orbit, a portion of which collected under the influence of gravity. This explains the similar isotope ratios as well as the lack of iron, as by this point most iron on earth will have collected in the core of the forming planet. Other moons within the solar system may have formed by this process, or by those previously mentioned. | |
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== Reference == | == Reference == | ||
<references/> | <references/> | ||
Revision as of 23:23, March 17, 2007
Various theories regarding the origin of the moon have been considered as follows:[1]
- One theory was that the Moon formed in an orbit around Earth, at the same time that Earth formed. But the lack of iron on the Moon, in contrast with the abundance of iron on Earth, disproved this.
- Another theory was that the Moon formed elsewhere in the solar system where there was little iron, and was later captured by the Earth's orbit. This failed upon examination of lunar rocks, which exhibit the same isotope composition as the Earth.
- Yet another theory was that the Earth spun off the Moon. This solves the isotopic similarity, but an analysis of the total angular momentum and energy involved shows that this is impossible in light of the current orbit. Also, spinning of the Moon would have given it iron also.
- The final theory, now generially accepted, is that that impact with a large planetesimal released a great quantity of debree into orbit, a portion of which collected under the influence of gravity. This explains the similar isotope ratios as well as the lack of iron, as by this point most iron on earth will have collected in the core of the forming planet. Other moons within the solar system may have formed by this process, or by those previously mentioned.