A recent study by astronomers using celestial mechanics has revealed that the Moon is older than previously believed, suggesting that it formed shortly after the Solar System came into existence.
Hardly anyone questions the details surrounding his birth: the Earth’s collision with another protoplanet, resulting in fragments that came together to create the Moon.
His age is a topic of discussion, typically determined by the rocks formed when the original magma of the lunar crust cooled, dating back 4.35 billion years.
The Moon likely formed around 200 million years after the start of the Solar System, according to Alessandro Morbidelli, a professor at Collège de France and one of the authors of the study published in Nature.
He questions the expert on planetary system formation and evolution, stating that it is excessive.
The delay is a concern for two main reasons: it does not align with planetary formation models, and it goes against the existence of zircon crystals that are over 4.5 billion years old.
A conversation about the topic from the previous year between two other researchers, Thorsten Kleine from the Max Planck Institute and Francis Nimmo from the University of California in Santa Cruz, led to a seemingly straightforward concept… Or so it seemed in theory.
Morbidelli explains that the Earth has caused a second merger of the Moon.
The Moon likely took shape around 55 million years after the Solar System’s formation, rather than 200 million years. It subsequently developed its initial crust within a few million years.
A phase of being slightly eccentric.
The Moon started moving away from Earth as a result of celestial mechanics. It shifted from being in an orbit parallel to Earth’s equator to being aligned with Earth’s orbit around the Sun.
During this change, he experienced a period that was “slightly chaotic and dynamic, a bit crazy,” as Morbidelli describes it. This orbital shift created tidal forces that impacted the Moon’s interior.
The gravitational forces on Earth caused the lunar mantle beneath the crust to partially melt approximately 200 million years after the Solar System’s formation, resulting in a less rigid lunar crust.
Volcanic activity on the Moon led to changes on its surface, with some areas sinking as a result of melting.
Tide forces are a common occurrence, as seen in Io, a moon of Jupiter that experiences continuous volcanic eruptions.
The Moon’s tidal forces were strong enough to partially meld the crust and restart the rocks’ radioactive clocks.
This clarifies why basaltic rocks at various depths in the “rejuvenated” crust appear to share the same age when analyzed using techniques relying on the decay of specific atomic elements.
One can determine the age of the most recent crystallization by measuring when the rocks are rediscovered and reformed, according to Morbidelli.
Impact on the history of the moon –
The authors of the study suggest that this phenomenon could also clarify certain physical attributes of the Moon, such as a lower number of meteorite impact basins than expected based on models. These basins may have been filled by magma during the second collision.
The researchers’ suggestion appears to be a clever solution, reminiscent of the well-known “Columbus’ Egg.” Morbidelli stresses that arriving at this finding involved some “dynamic and thermal modeling.”