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Theia and Earth were neighbors, new research suggests

https://phys.org/news/2025-11-theia-earth-neighbors.html

About 4.5 billion years ago, the most momentous event in the history of Earth occurred: a huge celestial body called Theia collided with the young Earth. How the collision unfolded and what exactly happened afterward has not been conclusively clarified. What is certain, however, is that the size, composition, and orbit of Earth changed as a result—and that the impact marked the birth of our constant companion in space, the moon.

What kind of body was it that so dramatically altered the course of our planet's development? How big was Theia? What was it made of? And from which part of the solar system did it hurtle toward Earth?

Rimu - 3w

Long before the devastating encounter with Theia, a kind of sorting process had taken place inside the early Earth. With the formation of the iron core, some elements such as iron and molybdenum accumulated there; they were afterward largely absent from the rocky mantle.

The iron found in Earth's mantle today can therefore only have arrived after the core was formed, for example on board of Theia.

If all of the iron that we have available to us is only there because of a freak collusion then most other life-friendly planets in the universe would not have iron. This would severely slow their technological development. No iron age, no steam engines. No horse shoes.

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swab148 - 3w

No iron armor, no iron pickaxe... This has profound implications for Minecraft lore

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SolacefromSilence - 3w

I'm thinking the implications are more basic.

Would there be enough iron so life would evolve with hemoglobin that needs iron?

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mnemonicmonkeys @sh.itjust.works - 3w

Copper can be used as an alternative. There's some fish species near Antarctica that do it

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