A new study of lunar rocks provided new evidence suggesting that the moon was formed from Earth's collision with another planet-sized body around 4.5 billion years ago.
The study confirmed the common belief among many scientists about how the moon came to be. Scientists formulated this theory after measuring the ratios between isotopes of oxygen, titanium, silicone and others.
A team of German researchers examined isotopes of Earth and Theia, the name given by the scientists to the colliding body. Their analysis revealed that the isotopes of the two bodies had close similarity, providing evidence that the moon, indeed, was a portion of the Earth that came out after its collision with Theia.
"The differences are small and difficult to detect, but they are there," said Daniel Herwartz, lead author of the study, in a press release.
The researchers used lunar rocks taken from meteorites hitting the Earth, but these samples exchanged their isotopes with water from Earth. Using the samples from the moon collected by the Apollo 11, 12, and 16 missions, the researchers produced more reliable samples to work with and found significantly higher levels of 170/160 on the lunar samples compared with their Earth counterpart.
The discovery established two things: first, that the collision did take place, and second, Theia seemed to be "E-type chondrites." The researchers also used the lunar rocks to predict the geochemical and isotopic composition of the moon.
"The next goal is to find out how much material of 'Theia is in the Moon," added Dr. Herwartz.
Scientists believed that Theia contributed around 70 percent to 90 percent to the composition of the Moon, with Earth accounting for the rest. Previous models suggested that the contribution was only eight percent, yet Dr. Herwartz estimated that it could be 50 percent.
The results of the study were published in the June 6 issue of Science and will be presented to the upcoming Goldschmidt geochemistry conference in California.
