Ancient lunar melting event may explain 150 million year gap in estimated ages

Ancient lunar melting event may explain 150 million year gap in estimated ages

Written by Payal Dar Edited by Sarah Lewin Frazier

The Moon is Earth’s closest neighbor in the universe and the only extraterrestrial body visited by humans. But scientists still don’t know exactly when a Mars-sized meteorite hit the early Earth, and its debris formed our natural satellite. Moon rock samples suggest this event happened 4.35 billion years ago, but planet formation models and zircon debris from the moon’s surface suggest it was 4.51 billion years ago. It is estimated that

A new study was published on December 18th. nature It provides a way to explain that 150 million year gap. Computer modeling and analysis from previous studies suggest that the 4.35-billion-year-old rock samples are not from the time of the moon’s formation, but rather that later in its history, when the moon briefly heated, the surface melted and crystallized. It has been suggested that this may have been an evolving event.

Because the Moon is slowly moving away from Earth, its orbit is not circular. As it moves, it is compressed and stretched by Earth’s gravity, resulting in a phenomenon known as tidal heating. One of these heating events probably occurred 4.35 billion years ago. This early moon would have resembled Jupiter’s moon Io, says Francis Nimmo, lead author of the new study and a planetary scientist at the University of California, Santa Cruz. “There would have been volcanoes all over the Earth’s surface,” he says. This event may also have erased the moon’s impact basins caused by meteorite impacts, which researchers also use to estimate age.

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This 150 million-year difference is extremely important to scientists, especially for learning more about the early Earth, Nimmo said. “The moon is moving away from the Earth, but the rate of movement depends on what the Earth is like,” he says. “Was it solid? Was it liquid? Was there an ocean? Did it have an atmosphere?” For example, there’s a good chance that the very early Earth didn’t have an ocean, or else we’d have missed the moon too soon. I would have pushed it away. The moon’s formation time is crucial to these calculations, and more complex models of tidal heating and associated mineralogy may help refine our views in the future.

“No study to date has comprehensively synthesized all the available evidence,” says Yoshinori Miyazaki, a geophysicist at the California Institute of Technology who was not involved in the study. “This paper provides a better perspective on resolving the discrepancy between different age estimates.”

Current hypotheses for when the Earth and Moon formed range from 30 million to 150 million years after the birth of the Sun, suggesting very different scenarios for planet formation. “Resolving these uncertainties is essential to building a coherent picture of the solar system’s history,” Miyazaki says.