U.S. intelligence agencies are expected to deliver a report on “unidentified aerial phenomena” to Congress next month, sparking renewed interest and speculation into how the government has handled sightings of mysterious flying objects — and if there's any worldly explanation for them.

The unclassified report, compiled by the director of national intelligence and the secretary of defense, aims to make public what the Pentagon knows about unidentified flying objects and data analyzed from such encounters.

While UFOs have been part of American mythology for decades, this report is different. Legitimate debates over UFO sightings have gained traction in recent years after several leaked photos and videos from the U.S. Navy appeared to show mysterious flying objects in American airspace.

Last year, the Pentagon declassified three such videos captured by Navy pilots, intensifying speculation over the incidents, which have been confirmed by pilots who have observed them and even presidents who have been briefed on them. 

Here’s how UFO sightings jumped from the realm of science fiction to the halls of Congress.