Oct. 14, 2021
A new study supports the theory the moon coalesced from material blasted into space after a Mars-size body slammed into the proto-Earth more than 4.4 billion years ago. "The standard model for the moon requires a very slow collision, relatively speaking, and it creates a moon that is composed mostly of the impacting planet, not the proto-Earth, which is a major problem since the moon has an isotopic chemistry almost identical to Earth," said lead author Erik Asphaug, professor at the University of Arizona's Lunar and Planetary Laboratory.