Today's Earth, with atmosphere, liquid surface water and other life-friendly conditions, only started to develop after the impact or impacts that formed the moon, so if that occurred late then life could only have developed late as well, she added.
"Our age places the impact(s) really early, which allow an hospitable Earth to develop much earlier as well," Barboni said.
The finding dovetails with related research showing early Earth was habitable earlier than previously thought, with the potential for life as far back as 4.1 billion years ago.
Having a moon-forming impact or impacts 4.3 billion years ago would leave relatively little time for life to evolve.
"At 4.51 billion years, you have much more time to transform the Earth from hellish to nice," Barboni said. "The age of the moon is indeed critical."
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To determine the moon's age, Barboni and colleagues used a new technique to examine eight zircon fragments left over from a previous study. Their uranium-lead dating method, used for the first time on lunar samples, corrects for cosmic ray exposure. The researchers also analyzed isotopes of the element hafnium, a silvery grey metal.