Scientists have uncovered new details about the Moon’s early history, pinpointing the time it solidified into its current state. By analyzing Apollo mission rock samples, researchers at the University of Chicago have determined that the Moon’s crust formed approximately 4.43 billion years ago—coinciding with Earth’s transformation into a habitable planet.
A Molten Beginning
The Moon originated as a molten body after a colossal impact between Earth and a Mars-sized object known as Theia. Over time, it cooled, forming distinct layers. The final remnants of its vast magma ocean created a unique chemical mixture called KREEP—an acronym for potassium (K), rare earth elements (REE), and phosphorus (P). Scientists believe studying these elements can help refine the Moon’s timeline and offer insights into its early evolution.
The Role of Lutetium and Hafnium
To determine the Moon’s solidification period, scientists measured the ratios of lutetium, a rare earth element, and hafnium, its decay product. By comparing Moon rock samples with meteorites formed around the same time, they confirmed that KREEP layers formed about 140 million years after the birth of the Solar System. This crucial finding supports the theory that the Moon’s surface fully crystallized around 4.43 billion years ago.
Linking the Moon and Earth
The timing of the Moon’s cooling aligns with a significant period in Earth’s development. Scientists believe the Moon-forming impact was likely the last major collision Earth experienced. This stabilization may have set the stage for Earth’s transformation into a life-supporting planet.
Future Exploration
Researchers hope to further validate their findings through samples collected from the Moon’s South Pole-Aitken Basin by the upcoming Artemis and Chang’e missions. These new samples could help refine lunar history, shedding light on how the Moon and Earth evolved together.
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“This discovery not only solves a long-standing mystery but also opens new doors for understanding the early Solar System,” said lead researcher Nicolas Dauphas. “With upcoming missions, we anticipate even more exciting revelations.”
