Let's assume the moon was formed because Earth collided into Theia. (There are numerous other theories, but this one is the most widely accepted.)

In that case, are there theories that address what the Earth surface looked like? E.g. would the Earth have had bodies of water at the time?

I've read some websites and a book!, and some say it did, some say it did not.

  • $\begingroup$ I would suggest, but I'm not an expert in such things, that Earth was so young when the impact happened that it still had considerable surface heat due to formation and frequent impacts. Some estimates put Earth at as young as 30 million years when the giant impact happened. I imagine it had water and an atmosphere, but I'd only be making guesses as to how much. $\endgroup$
    – userLTK
    Feb 12, 2019 at 12:40
  • $\begingroup$ I've modified the wording so that the question asks for theoretical research on the topic. This still matches the existing answer. No need to close as "primarily opinion based." $\endgroup$
    – uhoh
    Feb 25, 2019 at 6:44

1 Answer 1


Greenwood et al suggest that Earth had a lot of its water (maybe upto 70%) before Theia, but I can't find anything definite saying that it was liquid, although several sites reporting on the Greenwood paper assume that Earth was cool enough to have an ocean. It almost certainly had a crust, though. And immediately after the impact it had a magma ocean for quite a while. ;)


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