Ptolemy

Latest research analysing the moon and earth suggests the impact was head on and earth and the moon formed with theia being equally dispersed into both bodies. This is the only explanation for the formation of such a relatively large moon in such close proximity. Obviously any atmosphere would have had to form after this event. The question is how critical is the moon to making our planet habitable. Also this impact is credited with redistributing the heavy metals closer to the surface. The next question would be how rare are such collisions where the impact is sufficient to cause this effect but no so violent as to obliterate the two bodies, and take place in the Goldilocks zone. What is not yet known is if this significantly change earths orbit distance By equally, I meant uniformly

I agree but some thinking places thea at much greater perhaps as much as a similar mass to earth. The real question is if and by how much this was a factor in producing a habitable planet, especially the realatively large and close moon. Your thoughts?

Re the "core" energy I mean the energy ,mainly heat,with the core that keeps the magma molten thus providing the magnetic field essential for our atmosphere. Re the proto earth mass, if the collision with theia was head on, as now thought probable, the matter of both would be largely combined and the majority of ejected matter formed our moon, hence the proposal the earths mass must have increased.

This may indeed have been the case,however, the mass and makeup of the original earth may not have had the size and energy in its core to sustain an atmosphere resulting in a temperature and radiation exposure that would have boiled the water away leaving earth in a Mars like state.

The problem with "Drake" is that it does not take account of factors that appear to be crucial for life on Earth to evolve into complex forms. These are the strong magnetic field allowing our atmosphere to have lasted long enough and the interaction of our large moon which acts as a brake on the earth rotational spin rate. It is now probable that the earth and moon was formed by a head on collision of two smaller planets. This means the original mass of "earth" was significantly lower, ie earth and moon mass minus the mass of collision planet. The question is what effect this has had? Would the plant geology be different?,the collision is likely to have allowed heavier elements to have been redistributed nearer the surface, significantly increased mass and makeup of core and formed a relatively large and close moon. The moons relative gravity to earth is considered important in early life development. The question is how unique is this event in the universe when added to other factors in reducing likelihood of similar complex life coming into existence?