A recent study published in Nature challenges established beliefs regarding the Moon's formation, suggesting it may be older than previously thought. Researchers propose that instead of forming 4.35 billion years ago due to a massive impact, the Moon could have undergone a process of 'remelting' or reheating, affecting the age of its lunar rocks.
Traditionally, it has been believed that the Earth and Moon originated from similar materials as a result of a colossal collision between two celestial bodies. NASA states that the Moon formed approximately 200 million years after the solar system's creation. However, some scientists question the validity of this theory, pointing out that it does not account for the age of certain minerals, such as zircon crystals found on the Moon's surface.
Francis Nimmo, a professor at the University of California, Santa Cruz, and the lead author of the study, suggests that the age of lunar rocks could have been 'reset' by a global heating event caused by Earth's tidal forces. This phenomenon, known as tidal heating, occurs when the gravity of two celestial bodies generates internal friction, resulting in heat. The models presented indicate that during the Moon's early years, its orbit was unstable, intensifying these tidal forces.
The global reheating of the Moon could explain the scarcity of lunar impact basins dating back to its formative years. This finding builds upon a 2023 study that suggested the Moon is approximately 40 million years older than previously believed, based on analyses of zircon crystals brought back by the Apollo 17 mission in 1972.
The next step in this research will be to understand how tidal heating may have reset the Moon's age. Scientists are hopeful that lunar samples collected by China's Chang'e 6 mission will provide valuable data. Additionally, more detailed models will be necessary as lunar missions continue, as further data will enhance the understanding of the Moon's past.
Nimmo concluded that this research aims to encourage further discussion and exploration regarding the Moon's history, striving for a clearer picture of its role in the history of our solar system.