Collision of Earth With Another Planet-sized Body Led to the Formation of Moon

Collision of Earth with another massive planet-sized celestial body led to the formation of moon, new evidence claims.

A team of German researchers analyzed fresh samples of Moon gathered by Apollo 11, 12 and 16 missions, which confirmed the long-held theory that 4.5 billion years ago a collision between Earth and a planet sized-body Theia, formed the Moon. 

Using refined techniques, the researchers compared the ratio of oxygen in lunar samples with those collected from Earth. Compared to Earth the lunar samples had heavier oxygen atoms.

"The differences are small and difficult to detect, but they are there. This means two things; firstly we can now be reasonably sure that the Giant collision took place. Secondly, it gives us an idea of the geochemistry of Theia," Dr Daniel Herwartz of the University of Goettingen
said. "Theia seems to have been similar to what we call E-type chondrites. If this is true, we can now predict the geochemical and isotopic composition of the Moon, because the present Moon is a mixture of Theia and the early Earth. The next goal is to find out how much material of Theia is in the Moon".

Models of the Great Collision state that Moon has 70 to 90 percent material from Theia and the rest 10-30 percent is from early Earth. The new analysis reveals that there is a possibility of 50/50 mix with Earth material but this is yet to be confirmed.

"We have now discovered small differences between the Earth and the Moon. This confirms the giant impact hypothesis," Herwartz told BBC News.

The finding will be presented at the Goldschmidt geochemistry conference in California on 11th June and is published in the journal Science.