What's happening?

Space: 1999: 1x17

The Last Sunset

Anonymous alien benfactors provide the wandering Moon with a breathable atmosphere. The Alphans rejoice as they realise they have a wonderful new home in their own backyard. Preparations are made to settle and begin building a new civilisation on the Moon’s surface. Koenig is suspicious of the aliens’ motives, wondering how long this generous gift will last.

Space: 1999: Season 1 Episode 17
Jan. 01, 1976