A new detailed simulation of that ancient catastrophe has shown that this process could take no more than a few hours.
According to modern concepts , the Moon was formed about 4.5 billion years ago as a result of a collision of a young Earth with the protoplanet Theia, which reached the size of present-day Mars.
The impact raised and mixed the substance of both celestial bodies, part of it ended up in near-Earth orbit and gradually laid down the satellite.
However, new simulations have shown that this process could take place much faster – literally in a matter of hours.
The isotopic composition of lunar soil samples is close to that of the earth. This suggests that the crust of the satellite was formed mainly from the substance of the upper layers of the Earth.
From the deceased Theia, Luna got a smaller part, although her remains may be preserved deeper in the bowels.
In addition, the impact should have thrown matter far enough beyond the Roche limit , below which the Moon would have been destroyed by the tidal forces of the Earth’s gravitational field, even before it had time to form. Existing collision scenarios are difficult to explain both of these facts.
Therefore, Jacob Kegerreis and his colleagues used the new SWIFT model, which allows them to simulate complex gravitational and hydrodynamic processes that occur with large amounts of matter.
For calculations, scientists involved the COSMA supercomputer, which simulated hundreds of collision options: at different angles, with different speeds and rotation of both celestial bodies. Simulation resolution reached 100 million particles, orders of magnitude greater than usual.
The work showed that as a result of the collision of the Earth and Theia, two clumps of ejected matter appeared in orbit.
The gravity of the larger one could quickly push the smaller one into a more distant and stable orbit. He himself fell below the Roche limit and was destroyed.
The whole process took several hours and resulted in the appearance of the Moon with all its key features, including a wide orbit, a thin crust consisting mainly of Earth’s matter, and a partially molten interior.
To verify these conclusions will allow the analysis of samples of lunar matter obtained not from the surface, but from the depths of the satellite.
This is the challenge facing future missions that are being prepared under the NASA Artemis program. “The more we learn about the appearance of the Moon, the better we understand the evolution of our Earth,” says Professor Vincent Eke, one of the authors of the new work.
“Their histories are closely intertwined and may be mirrored in the histories of other planets profoundly altered by similar or entirely different collisions.”
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