Authorities all over the world say UFOs are real, but what are they, and are they a threat? This series examines the best and latest evidence caught on camera.

Throughout history certain civilisations, events and objects have fascinated and inspired us, causing those involved to dig deeper and go further on a ceaseless quest to be the first to finally uncover the truth.

Humanity's drive to push the bounds of the known world sometimes results in tragedy - but science still remembers the breakthroughs.