Humans may have been curious about unexplained objects in the sky for millennia PBS documentary "What Are UFOs?" gets an airing in the U.K. to bring the uninitiated up to speed after interest was ignited by highly publicized sightings of unidentified objects by Navy pilots and leaks of a secret Pentagon UFO program.

Here's how to watch "What are UFOs?" online from anywhere with a VPN — and potentially for free.

"What are UFOs?" premieres in the U.K. on Wednesday, August 27 on BBC Four at 8 p.m. BST. It will be broadcast again on Thursday, August 28 at 1.35 a.m. BST and available to stream on BBC iPlayer. It has previously aired in the U.S, and is still available to watch on PBS in the U.S. and on PBS Passport in Canada and Australia. • WATCH FREE — BBC Four/ BBC iPlayer (U.K.)

• U.S. —

See Full Page