In July 1947, a US military balloon crashed near Roswell, New Mexico.

The event sparked one of the most famous, exhaustively investigated, and thoroughly debunked UFO conspiracies of all time.

The idea that the government had covered up the discovery of alien life in a crashed spaceship caught hold in the 70s and inserted a long metal probe into popular consciousness. 

Seventy-five years after Roswell, another balloon, a white speck first spotted hovering high over Montana, has caused a similar stir.