A new study finds that the moon may have undergone volcanic transformation, making it more than 100 million years older than rocks collected from its surface suggest.
There are many reasons to be suspicious moon Older. For example, rare zircon minerals on the moon indicate that the moon was born about 4.5 billion years ago. Furthermore, many scientists who model planet formation believe that a collision large enough to form the moon is unlikely to have occurred 250 million years after Earth’s origin. solar system. Although giant cosmic impacts were common in the early solar system, orbital dynamics models suggest that most of the massive rocks behind such giant collisions were swept into larger bodies about 4.4 billion years ago.
Now, a new study suggests a possible explanation for this difference – that the moon’s surface “remelted” 4.35 billion years ago. This would reset the age of lunar rocks, masking the moon’s true age.
Much about the moon’s origins remains shrouded in mystery. Previous research suggests it was formed in a collision between the newborn Earth and a Mars-sized rock Theiathe last huge impact in Earth’s history. However, the exact timing of this conflict remains uncertain.
To estimate the moon’s age, geochemists previously examined lunar samples collected by lunar probes. Apollo missions and other means. The rocks likely crystallized in the magma ocean that covered the moon after the last giant impact. Analysis shows that the moon is about 4.35 billion years old, which is a relatively young age. In comparison, the solar system began to form about 4.6 billion years ago, or 250 million years ago.
“You can’t necessarily use the age recorded in rocks to tell when the moon formed,” study lead author Francis Nimmo, a planetary scientist at the University of California, Santa Cruz, told Space.com.
The cause of this remelting is the same tidal effect that causes Earth’s oceans to rise and fall. Just as the moon’s gravity pulls on the earth, the earth’s gravity pulls on the moon.
When the moon was first born, it orbited Earth Much closer than now, the Earth’s tidal influence on the Moon was much stronger than it is now. The new study shows that the force exerted by the Earth on the moon can cause widespread upheaval and dramatic warming. This remelting may help explain why early impacts created fewer lunar basins than expected—which would have been obliterated.
“We’re not really overturning conventional wisdom, but reconciling conflicting hypotheses,” Nimmo said. “Dynamicists want an ‘old’ moon, while geochemists want a ‘young’ moon. Ours Recommendations cater to both.”
Researchers point out that Jupiter’s moons Iothe most volcanically active body in the solar system, experiences tidal forces similar to those the moon may have had early in its history, constantly reshaping its surface. “It shows how interconnected planetary science is,” Nimmo said.
All in all, Nimmo said, the team’s computer model shows that the moon “formed about 80 million years after the formation of the solar system.”
The new study predicts that future research could use lunar rocks obtained from China’s upcoming Chang’e-6 mission to the far side of the moon for testing. “Further return of lunar samples would be very helpful,” Nimmo said.
Scientists now plan to conduct more complex and realistic simulations to pinpoint the impact of tidal heating on the moon’s geology. They introduced in detail their findings Published online on December 18 in Nature.