The Minot control tower diverted a B-52 to investigate. The navigator on the B-52, Capt. Patrick McCaslin, remembers what he saw on the radar screen: "This thing was climbing out with us and maintaining the same heading we were. That was unusual. But what really watered my eyes [was] when this thing backed away and allowed us to turn inside of it."
Capt. Brad Runyon, the B-52's co-pilot, says he remembers the "overall object was a minimum of 200 feet in diameter and it was hundreds of feet long."
"It had a metallic cylinder attached to another section that was shaped like a crescent moon. I felt that this crescent moon part was probably the command center. I tried to look inside the thing, but all I could see was a yellow glow."
He says at that point he was fairly sure it was an alien spaceship, and when the crew members returned to base, they reported their sighting.
According to Blue Book's investigation, the crew of the B-52 and 16 witnesses on the ground said they saw a UFO that night. In its final report, Blue Book concluded that they were all probably just seeing stars.
The Air Force finally got out of the business of trying to explain UFOs in 1969 and closed down Project Blue Book after an independent commission concluded that UFOs were of no scientific interest.
But there was one loud, dissenting voice: Blue Book's once-skeptical chief scientist, Allen Hynek. After more than 20 years and more than 12,000 investigations, Hynek had become a believer.
In an interview at the time, he recalled how embarrassing it had been to take UFO accounts from military pilots during Blue Book because the Air Force had trained those men.
"They could say civilian pilots might've been untrustworthy, but they could hardly say that of their own military pilots. And we got case after case after case from military pilots, which never hit the press," he said.
Hynek spent the rest of his life investigating sightings and calling for a serious scientific inquiry into the UFO phenomenon. Most of his fellow scientists rejected his opinions.
In 1973, he founded the Center for UFO Studies in Chicago in an effort to conduct more research into alleged sightings. He died in 1986.