For the past fifty years, astronomers have embraced a theory of the Moon’s formation that predicts the entrance of Theia. It would have been an ancient Mars-sized protoplanet that crashed into Earth. From the debris formed by the collision, our satellite would have formed after millions of years.
Now, however, a new hypothesis is gaining ground, a theory that, thanks to a simulation, has reconstructed the formation of the satellite as an event that lasted only a few hours. The impact would have torn off a piece of the Earth, which when entering orbit would have become the Moon.
“Missions and studies like these and many others are constantly helping us to rule out more possibilities and narrow down the real history of both the Moon and Earth, and to learn more about how planets form throughout our solar system,” says Jacob Kegerreis, a computational cosmologist at the University of Durham (England).
The question that drove the research was: if the Moon is made mostly of Theia, why do many of its rocks have striking similarities to those found here on Earth?
To investigate different possible scenarios for the formation of the Moon after the collision, the authors of the new study turned to a computer program called SPH With Inter-dependent Fine-grained Tasking (SWIFT), designed to closely simulate the complex and ever-changing network gravitational and hydrodynamic forces acting on large amounts of matter.
According to Kegerreis, in the case of giant impacts, the standard resolution of the simulation is usually between a hundred thousand and a million particles, but in the new study, he and his fellow researchers were able to model up to a hundred million particles.
“The more we learn about how the Moon came to be, the more we learn about the evolution of our Earth,” Vincent Eke, a co-author of the study and an associate professor of physics at Durham University, said in a statement. “Their histories are intertwined and could be echoed in the histories of other planets changed by similar or very different collisions.”
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