A collision can present an extreme risk of violent impact to the brain in the skull, which can cause brain bleeds, bruising, or other traumatic brain injuries. (bhattlawgroup.com)
In one model, a low - energy impact leaves the proto - Earth and Moon shrouded in a silicate atmosphere; in the other, a much more violent impact vaporizes the impactor and most of the proto - Earth, expanding to form an enormous superfluid disk out of which the Moon eventually crystallizes. (sciencedaily.com)