Sci-Fi Planet: Altair IV from Forbidden Planet

Altair IV (from Forbidden Planet)

During the early 23rd century, the United Planets Cruiser C-57D has been sent to the planet Altair IV, 16 light-years from Earth, to investigate the fate of a colony expedition sent 20 years earlier.

Dr. Edward Morbius explains that he has been studying the Krell, the natives of Altair IV who, despite being far more advanced than humanity, had all mysteriously died in a single night 200,000 years before, just as they had achieved their greatest triumph.