Apollo 8 is famous for being the first time humans travelled to the moon - but the astronauts might not have been alone in space, if this image is to be believed.
Found at the end of a reel of film taken during the mission in December 1968, it appears to show a large triangular object sitting on, or above, the lunar surface.
The shape is three-dimensional, and seems to be creating its own shadow, prompting speculation that it could be a UFO.
To read more and view the video, click here.