In 1960, the US and the Russians picked up the radar signature of a massive spacecraft locking itself into Polar orbit above the earth- each country knew that itself and the other could not have possibly placed such a large satellite into orbit using the rockets then available. This unknown object was named 'Black Knight' and has never been explained.
The sci-fi writer Philip K. Dick became convinced that he was in telepathic contact with this entity, and wrote books about his subsequent 'revelations.' (P.D.K. is the author of 'Blade Runner').

The Black Knight remains above us in the sky.