Space: 1999 Season 1 Episode 16
After an encounter with a space-time anomaly, the Alphans find their Moon back in the Solar System on a course to re-enter Earth orbit. The celebration ends when it becomes apparent Earth is an inhospitable wasteland. The mystery deepens when they discover a duplicate Moon already in orbit and a duplicate Moonbase Alpha lying empty and deserted.
Serie: Space: 1999
Episode Title: Another Time, Another Place
Air Date: 1975-12-18