Massive Structures Deep in Earth's Mantle Identified as Remnants of Ancient Planet Theia, Moon's Creator

Caltech-led study solves long-standing mysteries of the moon's origin and planet Theia's fate, suggesting that massive iron-rich structures beneath Earth's mantle are remnants of Theia, which had impacted Earth billions of years ago to create the moon.

Caltech-led research suggests two massive, iron-rich structures deep within Earth's mantle are remains of Theia, an ancient planet that collided with Earth billions of years ago, also aiding in the creation of the Moon. The structures are each twice the size of the Moon and likely composed of different elements than the surrounding mantle.
The structures, known as large low-velocity provinces (LLVPs), were first discovered in the 1980s. They sit near the center of the Earth, one beneath Africa and one beneath the Pacific Ocean, and may be relics of Theian mantle materials.
Researchers believe that most of Theia was absorbed into the young Earth during the cataclysmic collision, forming the LLVPs, while the remaining debris from the impact coalesced to form the Moon. This theory provides an answer to both the origin of the Moon and the fate of Theia which has long frustrated scientists.
The theoretical collision between Theia and Earth was reported to significantly change Earth's composition and may have been key in bringing water, the essential ingredient of life, to Earth, thus setting the 'initial condition' for the unique evolution of life-hosting Earth.
Next steps include investigating how the early presence of Theia’s mantel material deep within the earth might have influenced Earth's interior processes, such as plate tectonics, and its effect on Earth’s early geological evolution.

South China Morning Post