New chemical measurement supports giant impact hypothesis for lunar beginnings
The messy details of the moon’s birth just got a bit neater.
Earth and its little lunar sister aren’t actually twins, a new chemical analysis of Earth and moon rocks reveals.
The findings help iron out a big wrinkle in the giant impact hypothesis, the only idea about the moon’s origin that hasn’t been shot down yet, says Harvard University planetary scientist Sarah Stewart, who was not involved with the study.
“When everyone saw this work, we all breathed a huge sigh of relief,” she says. “In my mind, the giant impact hypothesis is still standing.”
According to this hypothesis, about 4.5 billion years ago a Mars-sized body called Theia bashed into the Earth, spitting out debris that mashed together to form the moon. Computer analyses of the collision suggested that the moon should be made mostly of Theia’s remains.
Because objects in the solar system have unique compositions, scientists assumed that