I included the word theory in there, and I also said that it was full of holes.
Anyway, these are the panels that started it all http://www.mangahere.com/manga/one_piece/v48/c470/http://www.mangahere.com/manga/one_piece/v49/c472/
While this theory sounds like something you'd see on an ancient aliens episode, I do wonder if Oda is going to do anything with what Enel discovered. The moon people coming to earth explains how the old guy got this tech, maybe he was one of them.
Anyway that mini arc tells me 2 things: Enel can survive without oxygen ( awesome ) and that there are some alien shenanigans in OP. Whether Oda will do something with it remains to be seen.