A groundbreaking study published in Nature suggests the Moon may be over 100 million years older than previously thought, dating its formation to approximately 4.51 billion years ago. This challenges the long-standing estimate of 4.35 billion years and offers fresh insights into the Moon’s tumultuous early history.
For decades, scientists have theorized that the Moon formed after a Mars-sized object collided with early Earth. However, the new study, led by Francis Nimmo of the University of California, Santa Cruz, suggests that the Moon formed earlier, with a later event known as “re-melting” reshaping its surface.
This re-melting occurred as the Moon gradually drifted away from Earth. Earth’s gravitational pull generated intense tidal heating, resetting the “clocks” of lunar minerals and obscuring its true age.
“The Moon rocks reveal not when the Moon was formed but when this later heating event occurred,” explained Nimmo.
The findings align with arguments from researchers who believed the Moon formed earlier. Apollo mission samples had pointed to a younger Moon, but questions arose about the feasibility of a massive collision occurring 4.35 billion years ago, given the solar system’s state at the time.
This study also sheds light on the age of zircon minerals found in Apollo samples, which date back roughly 4.5 billion years. Nimmo’s team attributes their formation to tidal heating, a process similar to what occurs between Jupiter and its moon Io, where gravitational forces generate extreme heat.
Upcoming missions, including China’s Chang’e 6 and NASA’s Artemis program, are expected to further explore the Moon’s origins. Carsten Munker, a University of Cologne scientist not involved in the study, praised the research for reconciling differing theories on the Moon’s age.
“This study bridges the gap between opposing viewpoints,” Munker said, emphasizing that understanding the Moon’s timeline is crucial for piecing together the early solar system’s history.
Why the Revised Age Matters
Though the difference between 4.35 billion and 4.51 billion years may seem minor, it has significant implications for understanding the rapid evolution of the solar system.
“The solar system evolved swiftly,” Munker explained. “Pinpointing early events helps us better understand the formation of the Earth-Moon system and the broader cosmic neighborhood.”
This discovery not only redefines our knowledge of lunar history but also deepens our understanding of the chaotic and dynamic processes that shaped the solar system during its infancy.