Foo fighters were first spotted and named by Allied aircraft pilots during World War II. Foo fighters were basically unidentified flying objects (also described as "mysterious aerial phenomena") seen in the skies over the Pacific Ocean. First reported in November 1944, the foo fighters were initially thought to be a weapon of the enemy. However, the mysterious experiences were also reported by Axis forces and the cause remains unknown to this day.
The foo fighters were reported to be fast-moving, round, glowing objects that would follow aircraft. Sometimes they were said to resemble Christmas lights and pilots claimed that they seemed to toy with them before vanishing. Pilots reported that these objects would fly in formation with their aircraft and seemed to be under intelligent control. Foo fighters have never been reported to display hostile behavior. No aircraft could outmaneuver them and they could not be shot down. However, on one occasion, the pilot of a B-29 aircraft did manage to hit one, at which time the foo fighter burst into several pieces and fell to the earth below, setting several buildings afire.
Foo fighters have also been reported by ships at sea and appear to be invisible to radar. One theory is that these events could have been caused by ball lighting. Another is extraterrestrials. No one knows for sure.