January 12, 2017
The Moon is actually much older than we thought
By analyzing samples of the moon’s surface brought back by the Apollo 14 mission, researchers have found the Earth’s only natural satellite is 40 million to 140 million years older than previously thought, according to a new study published in the journal Science Advances.
The new study is the latest published report to investigate the age of the moon, a hotly debated topic among astronomers.“We have finally pinned down a minimum age for the moon; it’s time we knew its age and now we do,” study author Mélanie Barboni, a geochemist at UCLA, said in a news release.
A study published last year had concluded the moon was created when a young Earth was smashed into by a planetary body called Theia. The latest study put the date of that collision at around 4.51 billion years ago. The origin of the moon is such a captivating topic for researchers because it can reveal clues about the origins of the Solar System and our own planet.
Studying Moon Samples
To reach their conclusion, the team behind the new study performed uranium-lead dating on bits of the mineral zircon that were gathered from the lunar surface by Apollo 14 astronauts.
“Zircons are nature’s best clocks,” said study author Kevin McKeegan, a UCLA professor of geochemistry and cosmochemistry. “They are the best mineral in preserving geological history and revealing where they originated.”
The Earth’s collision with Theia would have produced a molten moon, which then hardened. Researchers have said most of the moon’s exterior was enclosed in magma immediately following its formation.
Uranium-lead dating performed in the study indicated when the zircons first showed up in the moon’s early magma surface. The study team also performed lutetium-hafnium measurements that showed when its magma was formed, which occurred earlier than previously thought, the study said.
“Mélanie was very clever in figuring out the moon’s real age dates back to its pre-history before it solidified, not to its solidification,” said co-author Edward Young, a UCLA professor of geochemistry and cosmochemistry.
Prior reports have determined the moon’s age according to moon rocks that had been tainted by a number of collisions. McKeegan said those rocks suggested the date of some other activities, “but not the age of the moon.”
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