What if an Alien planet was hiding at the center of the Earth?

This groundbreaking scientific discovery could revolutionise our understanding of the Earth and the Moon as we know them today. Pieces of an ancient planet might be deeply embedded within ours.

The story of two earths begins in the mid 1980s when geophysicists made an incredible find after they measured seismic waves passing through the Earth. Near the planet's core, there are two masses of iron-rich materials. Each is roughly twice the size of the Moon and consists of elements that are different from those in the Earth's mantle that surrounds them. These two bodies, referred to as continents, clearly come from elsewhere, but for the time being, their origins remain unknown. 

In 2019, Qian Yuan, a geophysicist by training, was attending a conference by Professor Mikhail Zolotov. There was a discussion about the Moon's formation and the most commonly accepted theory was presented: it resulted from a collision between the Earth and a Mars-sized planet named Theia. However, no trace of Theia has ever been found, concludes the scientist. Qian Yuan had asked the question: What if the mysterious unknown masses near the Earth's core were in fact the remnants of Theia? 

To find out, the geophysicist and his team conduct extensive simulations, varying Theia's chemical composition and the impact of the planet with ours. All experiments confirm that the collision could explain both the Moon's formation and the presence of material masses within the Earth. But how could such a massive explosion leave tangible traces? But shouldn't Theia's remnants have merged with Earth's in the forming process? Not quite.

Simulations show that most of the energy generated by Theia's impact dispersed into the upper half of the Earth's mantle, leaving the lower mantle colder than previously thought. As the lower mantle didn't completely melt after the impact, the iron-rich masses remained largely intact as they descended to the base of the mantle. Imagine coloured wax blobs sinking to the bottom of a lava lamp once it has been turned off. This could be the explanation that scientists have been looking for.

The next step will be to verify the hypothesis, and scientists have high hopes for the Artemis mission, for which NASA is developing new spacesuits, among other things. Once on the Moon, the goal is to retrieve pieces of the lunar mantle and compare their geochemical signature with that of the material buried in the Earth. If they match, it will prove that these are indeed Theia's remains, confirming the Moon's formation theory. Two mysteries solved for the price of one.