The shock from another planet to Earth was the origin of the Moon – The Confidential

Most planetary geologists believe that the Moon was formed by a giant impact between Earth and a planet-sized object called Theia about 4,500 million years ago. To confirm this, scientists have focused in recent years in measuring different isotopes-atoms of the same element with different numbers of neutrons, such as titanium or silicon in lunar and terrestrial samples.

The isotopic ratios vary between objects in the solar system, but it turns out that in the case of the Earth and Moon are very similar, which conflicts with the theoretical models of the major collision. If this really happened, the moon would have formed from fragments of Theia, and therefore, one would expect that its composition was different from that of Earth.

Now we can be reasonably sure that the great collision took place, and we have an idea of ​​the geochemistry of Theia

Now a team of German researchers, coordinated by Dr. Daniel Herwartz University of Gottingen, has obtained measurements of oxygen isotopes expected to provide evidence that the moon originated by Theia collision with Earth. The work is published today in Science and is presented next week at the congress of geochemistry Goldschmidt (USA).
Team found that lunar samples analyzed with higher values ​​in the isotopic ratio of oxygen-17 and oxygen-16 relative to terrestrial rocks. Specifically, the difference is 12 parts per million (± 3 ppm)

“The differences are small and difficult to detect, but they are there,” says Herwartz, who plays this poses two developments.: “Now we can be reasonably sure that the great collision took place, and also gives us an idea of ​​the geochemistry of Theia, which looks like it was similar to the type chondrites E (a kind of meteorite enstatite).”

“If this is true, he adds, we can now predict the geochemical and isotopic composition of the moon, because the moon today is a mixture of early Earth and Theia. The next goal is to figure out how much material is missing planet in the Moon. “

How is Theia on the Moon

Most models estimate that the moon contains between 70% and 90% of material Theia, and the rest from ancient Earth. Nevertheless, some scientists believe that there is only about 8% of the Moon Theia. By Meanwhile, new study results suggest something in between: “A mixture of 50% seems possible, but needs to be confirmed,” said Herwartz

Section of a chondrite type E, whose geochemistry is assumed similar to Theia

For the study, the team used its first lunar samples that had come to Earth via meteorites, but as they were contaminated for the exchange of isotopes to ground water, they decided to look more pure.

These the NASA provided from rocks collected during the Apollo 11 mission 12 and 16, and were then analyzed by a technique of mass spectrometry. With this same material although such isotopes such as titanium, but were not detected differences observed with oxygen.