© Lloyd, Charles Chandler

 

FORMATION AND LOSS OF ATMOSPHERE
However, each giant impact also flung some near-surface material away from Earth into space, and blew off a small amount of the growing atmosphere.

Earth retained much of its growing atmosphere during accretion, but most of the atmosphere formed near the end of accretion, being "degassed" catastrophically from the mantle. As long as the Earth was very hot, water at the surface became a thick steam atmosphere.

OCEAN FORMATION
Once the Earth cooled sufficiently, the steam atmosphere collapsed to form an ocean of water on the surface.

MOON FORMATION
It is likely that the Earth had cooled to the point where it had a solid crust when it was struck by the planetesimal "Theia", resulting in the formation of the Moon.