Zaria GorvettSenior journalist, BBC Future
Media caption,US military shares UFO videos filmed by Navy officers
Over the past few months, Nasa has been sifting through hundreds of UAP reports for its first ever serious investigation of them.
But what distinguishes intriguing incidents from tall stories, or simple cases of mistaken identity?
According to David Spergel, the chair of Nasa's UAP study, there is one easy explanation for the vast majority of UAP sightings: tricks of perspective.
There’s the time British astronaut Tim Peake accidentally mistook droplets of Russian urine for the lights of approaching alien spaceships, or the moment a veteran pilot flew past a suspicious object above Virginia Beach, only to discover that it was a Bart Simpson balloon.
However, for those incidents that do remain unexplained, it has never been more important to understand what’s really going on.
From intriguing new weather phenomena to atmospheric junk, if there is something strange going on in our skies, it may pose a threat to aviation.
And of course, on the outside chance that we did receive a visit from an advanced extra-terrestrial species – well, it would be a shame if we didn't even notice that they had turned up.
Read more from BBC Future about the UAP reports piquing Nasa's interest.