Magma-spewing volcanoes developed on the moon soon after its formation, according to a new study of a moon rock that fell to Earth.
The findings will help researchers understand how planets develop in their early stages, the study authors say.
An international team of researchers examined a 30-pound (13.5-kilogram) moon rock found in 1999 in the Kalahari Desert in the southern African country of Botswana.
"It seems like it came upon Earth relatively recently, unlike many lunar meteorites," said team member Mahesh Anand of Open University in Milton Keynes, England.
The meteorite landed on Earth about 200 to 300 years ago, Anand said. It was probably blasted free from the moon when an asteroid hit the lunar surface.
The age of the rock suggested that volcanoes had already begun erupting just 150 million years after the moon's creation.
The new study appears this week in the journal Nature.
Rocky History
Most researchers agree the moon formed around 4.5 billion years ago, when a Mars-size planet slammed into early Earth with a glancing blow.
The bulk of that other planet's matter stuck to Earth, but some of the matter shot out and then congealed to form the moon.
Earlier studies—based on rocks collected from the moon's surface during the Apollo missions between 1969 and 1972—suggested that the bulk of the moon's volcanic activity occurred after 3.9 billion years ago.
"Apollo-era research suggested that it took a long time for the moon's volcanoes to erupt," Anand said. (Read more about moon exploration.)
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