A study in the journal Science confirms: the impact with the planet Theia generated the Moon. Earth and satellite are cosmic twins
The Moon shouldn’t exist. Or rather, not like that. Venus has no satellites. Mars has two “ridiculous” ones, 10-20 km long. The Earth, on the other hand, carries with it a colossus 3,470 km in diametermore than a quarter of our planet. An anomaly that has driven planetary scientists crazy for decades: how do you explain it? With a catastrophic, brutal and at the same time creative impact: the clash between the proto-Earth (called “Tiamat”) and Theiaa celestial body the size of Mars, hurtling towards us at ten times the speed of a bullet. An event that could have destroyed everything and instead gave rise to our most faithful companion: the Moon.
Today that remote episode comes back to light thanks to a study published in Science and conducted by an international team ofUniversity of Chicago e of Max Planck Institute. A research that confirms the most accredited theory on one of the most fascinating mysteries of cosmic history: how was our satellite born?
The Moon is unique in the Solar System
Scientists have always wondered about its origin. Why does Earth have such a large Moon when other rocky planets either have no satellites (like Venus) or have tiny ones (like Mars)? Our satellite, with a diameter of 3,470 km, is an exceptional case: its radius is more than a quarter of the Earth’s diameter. It shouldn’t exist, at least according to the “classical” rules of the Solar System.
For years the “fission” theory dominatedaccording to which the Moon would have been torn away from the Earth, perhaps from the Pacific Ocean basin. A seductive explanation, supported by the surprising chemical similarity between lunar and terrestrial rocks. But scientists have defined it several times “an elegant confusion”.
Scientific confirmation
Today the impact theory is no longer just the most plausiblebut receives a fundamental confirmation. By analyzing 15 terrestrial and 6 lunar samples from the Apollo missions, the researchers demonstrated that the Earth and the Moon are chemically indistinguishableespecially regarding iron. The explanation is surprising and definitive: at the moment of impact, the Earth and Theia became a single body, with Theia’s core collapsed into the Earth’s mantle and the debris launched into space to slowly form the Moon.
Not only that: the study also confirms that Theia belonged to the inner solar systemexcluding interstellar and imaginative hypotheses — no alien spacecraft, as someone joked about comet 3I/Atlas.
Moon and Earth: cosmic twins
Since then, the Moon has remained tied to the Earth in a unique gravitational relationshipso narrow that it always shows us the same face. It’s not laboratory science. The Moon it slows down the earth’s rotation, stabilizes the climate, makes life possible as we know it. Without that catastrophic impact, Earth would be a different planet. Perhaps inhospitable. Primordial chaos generated balance. Like a Nietzschean metaphor, from destruction a new harmony was born. A terrible, but vital beauty: the eternal dance that accompanies us in the darkest nights.
