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Moon Space Science

New Evidence That the Moon Was Created In a Massive Collision 155

Posted by Soulskill
from the let-there-be-moon dept.
derekmead writes "New evidence that the giant impact hypothesis is correct: A paper published today in Nature shares findings of a chemical analysis of Moon rocks that shows fractional differences between the makeup of the Earth and Moon that most likely were caused by the collision between Earth and a Mars-sized planet around 4.5 billion years ago. Although the two are quite similar, it's been previously shown that Moon rocks lack volatile elements, which suggests they may have evaporated during the incredibly intense heat and pressure created during an impact event. But if the hypothesis that light elements actually evaporated from Moon rocks during their formation is correct, you'd expect to find evidence of elements being layered by mass — heavier elements would condense first, and so on. That process is known as isotopic fractionation — a concept central to carbon dating — and the Washington University team's results suggest they found exactly that (abstract). They compared the blend of zinc isotopes in Moon rocks and Earth samples, and found that the Moon rocks held slightly higher proportions of heavier zinc isotopes. If the Moon was indeed once part of Earth — which has been shown by extensive modeling (PDF) — the difference in the balance of zinc profiles would most likely be explained by lighter zinc isotopes evaporating away following a collision."
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New Evidence That the Moon Was Created In a Massive Collision

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  • by bennomatic (691188) on Wednesday October 17, 2012 @04:24PM (#41686447) Homepage
    ...that Pangea (the conglomeration of land which drifted apart to become our current continents) might have been the Earth's "exit wound", where the Moon's material separated. For me, this is a hunch, with no basis in scientific fact, so I'm not going to declare its truth or defend it, but I would not be surprised if, in 10 or 20 years, some evidence were to surface supporting this idea.

    I remember being a kid and thinking that South America and Africa would fit together like a puzzle, and this was long before I'd ever heard of Pangea. Since that time, it's my understanding that irrefutable evidence--basically, the matching of fault lines and mineral components--has been found to support this. Later, I remember having the idea that the Moon may have been spit out of the Earth as the result of a large collision. My hunch was specious as it was based only on the idea that its orbit is perfectly matched with its rotation speed (aka tidally locked), and I understand that it's possible for that to happen in other ways, but this seemed to me the best bet.

    That last idea led to the Pangea idea. Maybe I'll read the freakin' article to see if other people feel the same way.
  • Re:Old news? (Score:5, Interesting)

    by Kittenman (971447) on Wednesday October 17, 2012 @05:08PM (#41686969)

    Who DOESNT think the moon was caused by a collision, outside of a few Creationists?

    Tut. Look back at the past. I used to be a lot more into astronomy than I am now, and back in the 70s/80s, the thought that the moon was caused by a collision was not laughable, but looked at askance. One thought was that if there was a helluva collision, why wasn't the rest of the planet shattered into fragments (much like the poor chaps in the gap between Mars and Jupiter...). I took the "both formed together, dual planet" thesis as the latest there was 'til I read Bill Bryson (god help me...) in his book "A short history of nearly everything", or some such title.

    Every theory is blindingly obvious and unquestionable, 'til someone proves it isn't. T. H. Huxley read Darwin's "Origin of Species" and thought it stupid of him (Huxley) not to have thought of it. Same here ..

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