The Black Knight Satellite is the name given to an object captured on camera by NASA astronauts during a 1998 space shuttle mission.
Conspiracy theorists claim the satellite is of extraterrestrial origin and possibly up to 13,000 years old and orbiting Earth in near-polar orbit.
The legend has been circulating since the Sixties and now footage uploaded to YouTube channel Section 51 claims to be evidence of the alleged craft.
A caption beneath the video reads: “Leaked pictures from ISS show the 13,000 year old Black Knight Satellite UFO very close to Soyuz Spacecraft during approach to the Station.”