A team of researchers at the University of Maryland has generated a new isotopic fingerprint of the moon. The results of their study suggest that the impact of Theia into early Earth was so violent that the debris from the impact mixed completely before settling and forming the moon.
The research paper, "Tungsten isotopic evidence for disproportional late accretion to the earth and moon," by Mathieu Touboul, Igor Puchtel and Richard Walker, was published on April 8, in the advance online edition of the journal Nature.
"The problem is that Earth and the moon are very similar with respect to their isotopic fingerprints, suggesting that they are both ultimately formed from the same material that gathered early in the solar system's history," said Walker, a professor of geology at UMD and co-author of the study, according to the press release. "This is surprising, because the Mars-sized body that created the moon is expected to have been very different. So the conundrum is that Earth and the moon shouldn't be as similar as they are."
"The small, but significant, difference in the Tungsten isotopic composition between Earth and the moon perfectly corresponds to the different amounts of material gathered by Earth and the moon post-impact," Walker said, according to the press release. "This means that, right after the moon formed, it had exactly the same isotopic composition as Earth's mantle."
This finding supports the idea that the mass of material created by the impact, which later formed the moon, must have mixed together thoroughly before the debris combined and cooled. This would explain both the overall similarities in isotopic fingerprints and the slight differences in Tungsten-182.
"This result brings us one step closer to understanding the close familial relationship between Earth and the moon," Walker said, according to the press release. "We still need to work out the details, but it's clear that our early solar system was a very violent place."
This research was supported by NASA (Award No. NNX13AF83G).
