Black Knight satellite and other orbiting mysteries

Is the most infamous UFO for real? The Black Knight satellite and other orbital mysteries!

In 1998, while building the ISS, the Space Shuttle Endeavor crew spotted a bizarre object orbiting the Earth. Thus began the popularization of the Black Knight Satellite!

But is it for real? And if not, why does a team of astronomers believe that other extraterrestrial objects like it might be orbiting our planet at this very moment?