The Moon is much older than previously thought and likely formed more than four billion years ago, scientists in the US have found.
Their discovery was a result of analysis of rocks and soil collected by the Apollo 14 moonwalkers in 1971.
The estimate, from a research team from the University of California in Los Angeles, found the moon formed within 60 million years of the birth of the solar system.
Previous estimates ranged from within 100 million to 200 million years after the solar system’s creation, less than half the latest estimate.
The scientists conducted uranium-lead dating on fragments of the mineral zircon extracted from Apollo 14 lunar samples.
The pieces of zircon were minuscule, no bigger than a grain of sand.
“Size doesn’t matter, they record amazing information nonetheless,” lead author Melanie Barboni said, noting the moon held “so much magic”.
Some of the eight zircon samples were used in a previous study, also conducted at UCLA.
Ms Barboni said she was studying more zircons from Apollo 14 samples, but did not expect them to change her estimate of the moon’s age, from 4.51 billion to 4.52 billion years, at most.
“It would be more a double-checking than anything else,” she said.
The work of Ms Barboni and her colleagues appeared in the journal Science Advances.
She said the team was eager to learn more about the moon’s history and, in turn, the evolution of early Earth and the entire solar system.
In February 1971, Apollo 11’s Alan Shepard and Edgar Mitchell collected 41 kilograms of rocks, and used tubes to dig up soil while exploring the moon’s Fra Mauro highlands.
They conducted two spacewalks, spending nine hours altogether out on the lunar surface.
Scientists still to discover how Moon formed
The UCLA report is the second major moon study this week.
Earlier, Israeli scientists suggested the Earth’s constant companion may actually be a melting pot of many mini-moons.
The researchers proposed that rather than one giant impact that shaved off a chunk of Earth and formed the moon, a series of smaller collisions may have created multiple moonlets that eventually merged into one.
Ms Barboni said regardless of how the moon came into being, “you still end up at the end solidifying the moon as we know it today”.
The giant impact theory holds that the resulting energy formed a lunar lava ocean that later became solid. It is the date of this solidification age that Ms Barboni and her team believe they have established.
“We finally pinned down a minimum age for the moon formation, regardless of how it formed,” she said.