Of all the various kinds of UFO related phenomena, which have materialized, the so-called light spheres certainly hold a particularly important place. These objects have recently gained greater popularity thanks, in part, to the studies conducted by Dr. Eltjo Haselhoff. According to his theory the light spheres could be the cause behind crop circles with which they have often been associated, but the spheres began to appear many years ago.

During the Second World War airplane pilots on both sides of the war reported on several occasions that they were flanked by mysterious light spheres during their missions. These spheres could execute maneuvers that would have been impossible for the pilots' airplanes. Their many attempts to out strip the spheres and avoid pursuit were unsuccessful and, in fact, the spheres often seemed to anticipate the maneuvers of even the most experienced pilots.

They appeared in all areas involved in the war from Europe to the Far East and it was soon clear that they were not secret enemy weapons. They were given the name "foo-fighters" from a corruption of the French word “feu”. The objects appeared to be glowing bright spheres in colors ranging between red, orange, yellow, white, and green. The instruments aboard the planes experienced malfunctioning when these mysterious craft appeared and once radar technology became operative the pilots realized that the craft were not detected by their radar devices.

The phenomenon of flying spheres begins to manifest during the second World War during the air attacks among American, English, German, and, of course, Italian and Japanese air forces. They all reported a presence of these spheres. Each of them thought they were secret enemies' weapons and so they were frightened, as they moved with great freedom. They could come very close to or move away from airplanes, almost passing between them.

The committees established by both the Allies and the Germans to investigate the phenomenon did not officially reach any serious result. Initially the pilots and their superiors were bewildered and, understandably, afraid that the spheres were secret enemy weapons. They later became accustomed to this presence considering it innocuous. According to the pilots' statements, the objects were filmed on several occasions, but the films have since been kept in secret military archives.

Footage filmed by random witnesses began to appear in the 1950s. These films show the objects both alone and in groups and images confirm the statements made by the military pilots. Amongst the first to suggest that these craft may be extraterrestrial was the Polish-American, George Adamski, the first and most famous of the contactee - that is human beings who come into repeated contact with beings presumed to have come from other worlds.

Adamski declared that these flying objects were remote controlled surveying probes that extra planetary spaceships had launched into earth's orbit for study purposes. Their shape could be spherical or disc like and their size could vary from just a few centimeters to several meters in diameter. He filmed a number of them in flight. Over the course of the years further films added to the wealth of footage showing these mysterious craft, giving a sense of continuity to their mysterious presence and origins.