This alien planet, Theia, was thought to have completely disappeared in the collision. AdvertisementAdvertisementAs well as shedding new light on the inner workings of our planet, scientists hope they will one day have access to these slabs of alien rock to reveal, once and for all, how our moon formed. The assumption has long been that Theia melded into moon, the Earth's mantle, and its core, in effect disappearing completely. Previous theories have suggested this core-mantle boundary could be made up of bits of ancient ocean floors. The problem is that the core-mantle boundary is very far from the surface — about 1,800 miles.

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Persons: Theia, Vincent Eke, Jacob A, haven't, Edward Garnero, Li, Hongping Deng, Everest, Deng, Christian Schroeder Organizations: Service, Arizona State University, Chinese Academy of Sciences, Durham University, University of Stirling Locations: Theia, Iceland, Samoa