The study of zircon crystals, these minerals brought back by the Apollo missions, now allows us to date the age of the Moon with greater precision. Thanks to modern analyses, we now know that this would be older than traditional estimates. Its chronology is more complex than that previously considered, where the lunar formation, resulting from the collision between the primitive Earth and a celestial body of Martian dimensions, seemed solidly anchored at 4.35 billion years.
When the crystals speak
Lunar zircons are very effective time markers; their molecular architecture, resistant to the most intense geological transformations, preserves the imprint of the physico-chemical conditions of their formation. Examining these left us with a little surprise: while the lunar surface bears the mark of a global remelting dated 4.35 billion years ago, certain zircons have retained their primitive structure intact. These zircons are therefore older than the fusion and bear witness to this fact from an earlier period of lunar history.
Isotopic analyzes now place the birth of our satellite in a precise time interval: after the formation of its core at 4.53 billion years, but 180 million years before the thermal upheaval which reshaped its surface. The new age of the Moon is therefore between 4.42 and 4.53 billion years ago.
Thermal phenomena at the origins of the lunar transformation
According to our contemporary geophysical models, the thermal remodeling of the lunar surface would be the result of a set of complex gravitational interactions. Calculations demonstrate that the mechanical constraints exerted by the Earth-Sun system generated sufficiently powerful tidal forces to cause partial melting of the lunar crust.
This hypothesis, supported by advanced numerical simulations, excludes the scenario previously considered of an intensive meteorite bombardment. The work published in April of this year in the review Nature Geoscience also document a phenomenon of reversal of the lunar internal structure during its first millions of years. The lunar mantle, the layer between the core and the crust, would have turned over and this phenomenon would have taken place very early in the history of the Moon, probably in the first millions of years after its formation.
NASA’s Artemis program, by allowing the in situ analysis of new geological samples, will provide us with essential data to validate these theoretical models and clarify our understanding of primitive thermodynamic processes. Unknown geological phenomena could even be identified (presence of certain minerals or particular structures) and thanks to these new samples, researchers will retrace the evolution of geological processes with more precision. which affected our satellite. Roll on 2026! This will be the year when the mission Artemis III should take place, which will be the first to land astronauts.
- Lunar zircon crystals indicate that the Moon is older than traditional estimates, between 4.42 and 4.53 billion years old.
- A remodeling of its surface would have been caused by gravitational forces, invalidating the hypothesis of an intense meteorite bombardment.
- The Artemis program will soon offer the opportunity to analyze new samples, in order to better understand the geological evolution of our satellite.
