A half hour UFOTV documentary, "Journey To The Hollow Earth," provides good intro into theory our planet may be hollow. Astronomer Edmond Halley and Mathematician Leonhard Euler believed in a Hollow Earth. Program alerts viewer to International Society of Complete Earth, an organization striving to become a central authoritative source on Hollow Earth theory. Did you know Smithsonian Institute got its start with artifacts brought back from an expedition President John Quincy Adams supported in 1828 to search for Antarctic opening to the inner Earth? Prior posts are linked on Hollow Earth and secret diary of Admiral Richard Byrd flight to the North Pole.