I remember this from when I was a kid.
I thought this was long accepted.
When I was a kid, and even into my early adulthood, science never really got behind the idea that most craters were impact features and not volcanic in nature. Us ordinary mortals all laughed at what seemed to be “The Sky Is Falling” hysteria. What a bunch of Chicken Littles!
Then Eugene Shoemaker came along and finally clinched it for the impact crowd, first for many craters on Earth, then again for the Moon’s craters when he worked on the Apollo program. That was 1969. So impact theory is very, very recent. It just wasn’t accepted before Shoemaker.
I can’t for the life of me recall a theory from back then that claimed a huge magma ocean which covered the Earth splashed out into outer space after a giant impact, ultimately coalescing and cooling to become our Moon. Impact theory just wasn’t accepted before ‘69. And after that I was too interested to have missed it. Or so it seems. More details please, so I can check it out. Very interesting, thanks.