>Or maybe I'm just not understanding that "theory" well enough From what you've written, I think you are misinterpreting the standard theory, which is much mor

>Or maybe I'm just not understanding that "theory" well enough From what you've written, I think you are misinterpreting the standard theory, which is much more like 'your idea' (the second paragraph) than your conceptualization of it in the first paragraph, i.e. there was no moon-sized solid chunk removed. I don't think any scientists working on this think that. Although there is some argument on the size of the impacting body (Theia), most/all the impact-origin theories hold that much of the planet was reduced to tiny liquid fragments and/or vaporized, including the material that became the Moon. Here is a video of a simulation of the the 'standard' theory: https://www.youtube.com/watch?v=wfImQOZp3hE https://www.youtube.com/watch?v=wfImQOZp3hE Something that is important to keep in mind, but is non-intuitive, is that all of the Earth with the exception of the upper crust (say, the upper 10-30 km of the Earth, radius 6378 km) is hot enough to melt if it was not under the confining pressure of the weight above it. Remove material from above the lower crust or mantle, and it undergoes decompression melting. So even if the material that coalesced to become the moon was removed through gentle caresses, without producing heat due to friction, that material would melt, and so would the rock surrounding the area that it was removed from. So you don't need to place the collision happening in a context where the Earth was much hotter (which it probably was to some degree regardless). Add in the enormous friction caused by collision, and you are in a situation where much of the Earth and possibly Theia are reduced to tiny particles of liquid (lava) or gas (vaporized basically), though these would cool to basically volcanic glass very rapidly in space. Then the Moon and the Earth's mantle were reassembled from these tiny particles. Caveat: I have a PhD in geology but my research is not in this area and I don't follow it closely.