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How old is the moon?

The age of the moon is the subject of some debate within the scientific community. Some scientists think that the moon formed roughly 100 million years after our solar system formed, while others favor a date somewhere between 150 and 200 million years after the solar system’s birth. These dates would put the moon between 4.47 billion and 4.35 billion years old.

A new study published in Science Advances claims to put the controversy over the moon’s age to rest. A team of researchers think they have accurately dated the moon at 4.51 billion years old.

The researchers used moon rocks taken from the lunar surface during the Apollo 14 mission in 1971 for their study. Most moon rocks astronauts have brought back to Earth are composites of rocks fused together during meteor strikes, and that makes dating them tricky as the different pieces of the rocks will reflect different ages. To get around this, the researchers turned to zicorn, a very durable mineral found in both the Earth’s crust and in moon rocks.

“Zircons are nature’s best clocks,”said co-author Kevin McKeegan, a UCLA professor of geochemistry and cosmochemistry. “They are the best mineral in preserving geological history and revealing where they originated.”

McKeegan and lead author Mélanie Barboni focused on the tiny zicorn crystals that contained small amounts of radioactive elements, particularly uranium and lutetium. They isolated when these two elements has decayed to calculate how long the zicorn had formed and used that to provide what they contend is an accurate age for the moon.

This isn’t to say that the zicorn-dating approaching is without its own controversy. Speaking to The Verge about the findings, Richard Carlson, the director for the department of terrestrial magnetism at Carnegie Institution for Science, he praised the work but cited concerns about the zicorn approach. Namely, Carlson questions the assumption that the decayed ratios for the uranium and lutetium would be the same in the early days of the solar system as they would be today.

“It’s just a very complicated problem they are addressing here, which is why we still don’t have a clear answer to such an obvious question as the age of the Moon,” Carlson said.

Source:  mnn.com

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