Firsoff has been superseded by evidence.
Formation from impact fits the evidence.
SunkinCiv, I would listen to this expert.
Thanks FF. From the first couple of posts:
"Although the nautiloid fossils have been used to prop up the impact origin for the Moon, the fact that more than 50 per cent of the Earth-Moon distance has accumulated in about ten per cent of the purported age of the Moon shows it isn't so."