It has been a long-standing suspicion of researchers that the Moon came to be after planet Theia, a protoplanet the size of Mars, smashed into Earth roughly 4.5 billion years ago. While not all specialists agree with this theory, a new study claims that it has unveiled new evidence to show that huge pieces of Theia could be found deep within the Earth.
Chunks of Theia on Earth
Researchers from the Chinese Academy of Sciences looked into two massive matter blobs, called large low-velocity provinces (LLVPs), buried deep under the Pacific Ocean and continent of Africa. The researchers then conducted fluid dynamics simulations to know where these blobs could have come from.
The scientists then simulated the smashing of a huge Theia-like object into the surface of the Earth. Doing so enabled them to find out that the upper half of the mantle of the Earth would have ended up melting during this full process. Resultantly, this would have allowed around 10% of the object to enter deep-Earth, close to the planet's core.
Hongping Deng, who is from the Chinese Academy of Sciences' Shanghai Astronomical Observatory (SHAO), explains that the findings challenge the notion that the massive impact resulted in the early Earth's homogenization. Rather than this, the impact could have been the commencement of the heterogeneity of the early mantle. It could have also served as the starting point of the geological evolution of the Earth in the course of 4.5 billion years.
The blobs would have ended up churning and growing due to the currents of the convection. They would have, in turn, formed the two different LLVPs.
Based on earlier simulations, it was concluded that the only pieces of Theia had melted into the Earth long ago. However, the recent study posits that there were chunks of planet Theia, roughly 10%, that ended up trapped inside the Earth. These chunks potentially account for 2% to 3% of the total mass of the Earth.
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A Testable Hypothesis
The good thing is that there is a way for this to be examined and tested. Geophysicist Qian Yuan, the lead author of the study, explains that in most impact simulations pertaining to the formation of the Moon, the majority of lunar materials were from the impactor. Hence, it can be expected from future missions to obtain rocks from the mantle and have the samples compared with the blobs to see if similar chemical signatures can be found.
Should this be the case, this would offer new tools for examining the formation and history of the planet and even the solar system. It could also aid with the understanding of other cosmic worlds and even in the search for life beyond the Earth.
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