The moon may have formed almost immediately after a devastating impact between Earth and a Mars-sized world in the ancient past, according to a new supercomputer study.
Earth’s moon is a silent witness to the history of our entire species. Its gravitational influence is responsible for the tides, and its simple presence in the night sky has profoundly influenced human cultural evolution.
But despite its ubiquitous nature, the scientific community has yet to agree on exactly how Earth’s largest natural satellite formed.
It is widely agreed that the Moon was formed when a roughly Mars-sized body in the Solar System – dubbed Theia – collided with Earth about 4.5 billion years ago. This impact devastated both our planet and the original Theia, sending vast amounts of material from both worlds into Earth’s orbit.
Many of the previous theories about the moon’s formation suggest that it slowly melted away from this soup of orbital debris until eventually the rest of the material not collected by the satellite fell back toward Earth.
In this scenario, most of the orbital debris would have consisted of the remains of Theia. However, rock samples recovered from the lunar surface by Apollo-era astronauts showed a surprising structural and isotopic similarity to those found on Earth.
While it’s possible, authors of a new study thought it unlikely that material from Theia would match Earth’s so closely.
In the new study, a team of researchers from Durham University in the UK used the powerful DiRAC supercomputing facility to run a series of simulations that could explain the formation of Earth’s moon.
The supercomputer used a significantly larger number of particles to simulate the ancient collision than previous studies. According to the team, lower-resolution simulations can omit important aspects of the collision process.
Over the course of the study, the scientists ran hundreds of these high-resolution simulations while varying a number of key parameters, including the masses, spins, angles and speeds of the two ill-fated worlds.
The simulations showed that a large body with a lunar-like mass and iron content could have coalesced in orbit almost immediately after the collision between Earth and Theia. The detailed simulation showed that the newborn hypothetical satellite would have been created beyond the Roche limit – that is the orbital distance at which a satellite can orbit a planet without being shredded by its gravity.
Furthermore, the outer layers of such a world would be rich in material ejected from Earth, explaining the similarities between Apollo-era rocks and those of our planet.
“This formation pathway could help explain the similarity in isotopic composition between the lunar rocks brought back by the Apollo astronauts and the Earth’s mantle,” explains study co-author Vincent Eke, associate professor in the Department of Physics at the University of Exeter. “There may also be observable consequences for the thickness of the moon’s crust that would allow us to further determine the nature of the collision that occurred.”
If the moon had formed rapidly after impact, its internal structure would likely be different than if it had grown gradually from a circumplanetary debris disk. Astronauts returning to the moon as part of NASA’s Artemis program in the coming decades will collect fresh samples from the lunar surface that can be used to test the theory of rapid formation.
The research could help update scientists’ understanding of how moons form in the orbits of distant worlds that spread across the universe.
Anthony Wood is a freelance science writer for IGN
Image source: Dr. Jacob Kegerreis
#Supercomputer #simulations #gave #explanation #moons #formation #IGN
Leave a Comment