Unknown World (a.k.a. Night Without Stars) is a 1951 independently made American black-and-white science fiction adventure film, directed by Terry O. Morse, and starring Bruce Kellogg, Marilyn Nash, Jim Bannon, and Otto Waldis. Distributed by Lippert Pictures, it was produced by Irving A. Block, Jack Rabin, and Robert L. Lippert.
The film's storyline concerns a scientific expedition seeking livable space deep beneath the Earth's surface in the event a nuclear war makes living above ground impossible.