[GeronL]

so.... if the moon formed from ejecta of a collision then does that mean what hit the baby Earth was bigger than the moon or maybe the same size?

[bigheadfred]

We picked up the moon from the planet that formed the asteroid belt when it was destroyed.

[America_Right]

so.... if the moon formed from ejecta of a collision then does that mean what hit the baby Earth was bigger than the moon or maybe the same size?

Bigger than the moon. Mars-sized. Mars is roughly twice the size of the moon. It stands to reason, seeing as that a good bit of the "stuff" from the impactor would have been left behind on Earth, while the ejecta turned into the moon.