"One of Our Planets Is Missing" is the third episode of the first season of the animated American science fiction television series Star Trek. It first aired in the NBC Saturday morning lineup on September 22, 1973, and was written by veteran Star Trek director Marc Daniels. It was directed by Hal Sutherland. In this episode, the Enterprise must contend with a massive space cloud that eats planets, now targeting a Federation colony of over 82 million inhabitants.