Parentage of moon confirmed: Earth and Theia, say scientists


An immense collision between Earth and a Mars-sized astronomical body called Theia may have formed the moon lighting up our night skies. New evidence presented in a study published in the journal Science supports the Giant Impact hypothesis.

Recall that previous reports also reveal that the moon may have come from the floating debris brought about by such collision. This came from the Giant Impact Hypothesis, a predominant and widely accepted explanation of the origin of the moon.

The new study, "Identification of the giant impactor Theia in lunar rocks," is said to confirm and support the immense collision.

The hypothesis suggested that Theia slammed into our planet about 4.5 billion years ago. The said collision tossed magma into orbit around our planet. The magma, both from Earth and Theia, condensed and then cooled into the rocky orb: the moon. This explanation is said to best illustrate why the moon swirls, has a small core and lacks water.

The new scientific study involves an analysis of the composition of moon rocks carried to Earth by Apollo astronauts, which shows fragments of Theia somehow supporting the hypothesis. The thin core of the moon, meanwhile, indicates that two other planets helped in creating it.

"The Giant Impact Hypothesis is very good in explaining most of the moon's features," lead study author Daniel Herwartz says. He is also an isotope geochemist at the University of Göttingen in Germany.

Meanwhile, various researches say some scientists still have doubts over the idea of a collision forming the moon because of its chemical composition. Collision models often show that the moon should be around 70 percent composed of Theia. Most of the planets in our solar system, however, have distinctive chemical compositions, as well as Earth and moon. What makes the moon and Earth look similar is in terms of versions of isotopes, as opposed to those models with Theia.

Herwartz admits to that it was indeed a "big puzzle" -- but not until now. Along with fellow researchers, he discovered differences in the isotopic composition of the moon and Earth. The differences support the Giant Impact Hypothesis.

The scientists initially studied the lunar rocks that landed as meteorites on Earth, following being thrown off the Moon by celestial impacts, but found that oxygen isotopes from Earth’s water tainted these rock samples. To replace this, NASA provided lunar rocks taken by astronauts who were in Apollo 11, 12 and 16 missions.

Findings from the new study indicate that the moon may be composed of Theia by around 40 percent. They suggest Theia was comparable to enstatite chondrites meteorites, which have a considerably parallel isotopic composition to Earth. Though the exact individual composition of Theia and Earth in the moon remains unknown, Herwartz now assures the giant collision actually happened.

Several reports gathered, however, show that not all scientists are impressed by the findings. One not impressed, for instance, is professor emeritus Robert Clayton of the University of Chicago, who says he doesn’t see anything new in the recent paper but simply a repackaging of error bars. On the other hand, Dr. Mahesh Anand of Open University also says the data were just based from three samples of lunar rocks, thus it requires further analysis of diverse lunar rocks to completely confirm the Giant Impact Hypothesis.

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