Complex sentence: This impact at a glancing angle would have either destroyed Theia or buried it into the Earth, and throwing massive quantities of ejecta into orbit around Earth, from which the Moon coalesced in a matter of months or days.
Split into simpler sentences: This impact at a glancing angle would have either destroyed Theia or buried it into the Earth. Massive quantities of ejecta would have been thrown into orbit around Earth, from which the Moon could have coalesced in a matter of months or days.