Everything we thought we knew about the moon’s origins is probably wrong, according to a new study written by two Harvard scientists. The leading theory since the 1970’s suggests a Mars-sized object scratched Earth in a “giant impact event,” leading to the moon. But new analysis of moon rocks reveals the collision that led to the moon was likely far more violent than we thought, which could offer insight into what the solar system was like long ago.
Kun Wang and Stein B. Jacobsen, who are both affiliated with the Department of Earth and Planetary Sciences at Harvard, scrutinized “old Apollo samples from the ’70’s” with better technology than was available 40 or more years ago. They found elements that couldn’t fully be explained by the old theory, including “heavy isotopes of potassium.” The process to separate out those potassium isotopes would have needed super hot temperatures. Those temperatures could have resulted after a very violent collision.
Wang told Gizmodo, “We need a much, much bigger impact to form a moon according to our study. The giant impact itself should be called extremely giant impact. The amount of energy required isn’t even close.”
Instead of the Mars-sized object scraping Earth, the collision would have been more akin to a “sledgehammer hitting a watermelon.” The collision was so hot and forceful that the scientists think some of Earth actually vaporized. When the vapor cooled, it condensed into our moon. Nature published their study online this week.
The new information about the moon’s origins led the scientists to think long ago, the solar system could have been a lot more violent and volatile. They think the moon rocks could hold more secrets about the “early solar system” and plan to keep probing the samples for more thrilling hints about the past.