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Why the Moon Is a Copy of Earth? The Fluidity Clue ⚡ экспресс

Original: "Giant impact between high-viscosity Theia and low-viscosity proto-Earth: Origin of lunar isotopic crisis"
· Wenshuai Liu
arXiv:2606.20398 · 2026-06-18 · CC BY · ⏱ 1 min · Exoplanets
The collision of solid Theia with a liquid Earth explains why the Moon is so similar to our planet.
Abstract

What if the Moon isn't made of what we thought? Scientists have offered an explanation for why the Moon is compositionally so similar to Earth, even though the old theory says it should resemble the impactor Theia. Imagine two balls of differently colored clay colliding and forming a ball mostly made from just one of them, because the other was too hard. Could this kind of 'hardness' solve the mystery of the Moon's birth?

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Young Earth was a boiling sphere of liquid rock, while Theia, which crashed into it, had had time to cool and solidify.

It’s like dropping a chunk of cold butter into a pot of soup: the soup splashes out, but the butter barely moves.

Similarly, Earth’s interior spewed into space, forming a cloud of cosmic dust and debris. From this, the Moon gradually coalesced. This hypothesis complements the standard model of the giant impact.

Analysis of lunar soil using light analysis (pioneered by Joseph von Fraunhofer) revealed that the atomic composition of the Moon and Earth is nearly identical. Decades of mystery were solved: due to the difference in fluidity, it was mostly Earth material that escaped into space. The most unexpected outcome: the Moon rocks brought back by the Apollo missions are frozen splashes of our planet. Holding them, you’re touching a shard of ancient Earth.

🎯 That same impact likely tilted Earth’s axis, giving us the seasons. So we have spring and autumn to thank that ancient catastrophe for.

Scientists
Christian DopplerD. B. McLaughlinDidier QuelozMichel MayorR. A. RossiterEmmy Noether
Tags
cosmic dust spectroscopy Standard Model
Laws
Doppler effectNoether's theoremMaxwell's equationsPlanck's lawPlanck–Einstein relationWien's displacement law
Original: arXiv:2606.20398 · CC BY · bridge42worlds