A team of researchers has made a significant discovery regarding the origins of the Moon and the presence of water on Earth. The commonly accepted theory posited that the Moon was created from a collision between the young Earth and the protoplanet Theia. However, new data suggests that the Moon actually formed from materials expelled from the Earth’s mantle, with minimal involvement from Theia. Additionally, this research supports the idea that water may have been delivered to Earth early in its history, rather than arriving solely from later impacts. The findings were published in the Proceedings of the National Academy of Sciences (PNAS).
A research team from the University of Göttingen and the Max Planck Institute for Solar System Research (MPS) has discovered another piece in the puzzle of the formation of the Moon and water on Earth. The prevailing theory was that the Moon was the result of a collision between the early Earth and the protoplanet Theia. New measurements indicate that the Moon formed from material ejected from the Earth’s mantle with little contribution from Theia. In addition, the findings support the idea that water could have reached the Earth early in its development and may not have been added by late impacts. The results were published in the Proceedings of the National Academy of Sciences (PNAS).
The researchers studied oxygen isotopes from 14 Moon samples and performed 191 measurements on minerals from Earth. Isotopes are different forms of the same element that vary only in atomic mass. They employed an enhanced technique called “laser fluorination,” which uses a laser to extract oxygen from rock samples. The results revealed a remarkable similarity in an isotope known as oxygen-17 (17O) between samples from both the Earth and the Moon. The isotopic similarity has been a longstanding issue in cosmochemistry, referred to as the “isotope crisis.”
“One explanation is that Theia lost its rocky mantle during prior collisions and then collided with the early Earth like a metallic cannonball,” explains Professor Andreas Pack, Managing Director of Göttingen University’s Geoscience Centre and Head of the Geochemistry and Isotope Geology Division. “If this were true, then Theia would now form a part of Earth’s core, while the Moon would consist of material ejected from Earth’s mantle. This scenario would clarify the similarities in their compositions.”
The data also sheds light on the history of water on Earth. According to a popular theory, water did not reach Earth until after the Moon’s formation, brought in by a series of later impacts known as the “Late Veneer Event.” Since Earth experienced these impacts far more frequently than the Moon, one would expect to see differences in the oxygen isotopes based on the origins of the impacting materials. “However, since our new data indicates otherwise, many meteorite types can be ruled out as the source of the ‘late veneer’,” explains Meike Fischer, the study’s lead author who was affiliated with the Max Planck Institute for Solar System Research in Göttingen during the study. “Our findings align particularly well with a group of meteorites known as ‘enstatite chondrites’, which share isotopic similarities with Earth and contain adequate water to account for Earth’s water supply.”
