From Mike Wall at Space.com:
A new analysis of lunar rocks brought to Earth by Apollo astronauts suggests that the moon formed 4.51 billion years ago — just 60 million years after the solar system itself took shape.
Astronomers think the Moon took shape from a collision between Earth and a Mars-size body but just when is unclear, from the jumbled rock samples available to be gathered by astronauts:
“You don’t have pristine, old rock preserved on the moon,” Barboni said. “That’s one of the biggest problems — the whole-rock record on the moon is not there.”
But zircon samples collected by Apollo 14 appear to provide reasonably clear information.
The moon’s advanced age also makes sense from a dynamics point of view, especially if the giant-impact(s) theory is correct, Barboni said. That’s because more impactors were flying around in the solar system’s very early days than 100 million years or so later, she said. More.
What’s surprising, really, is how little we know about the moon in general. For example,
Another moon origin theory: Epic crash
How the Moon Formed: 5 Wild Lunar Theories (Mike Wall at Space.com, 2014)
Our moon formed in collision with embryo planet?
Origin of the moon still shrouded in mystery
We probably knew more when we knew less, actually, because it is easier and safer to be dogmatic when there are no new discoveries and new insights are suppressed.
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