Rather more dramatic, but completely natural, was the ball of fire that raced through the skies over the Komovi Forest in Yugoslavia on the evening of 26 November 1967. The object was seen by a group of forestry workers who were sheltering from a sudden downpour of heavy rain. The object streaked through the sky, then plunged into the forest and set the trees alight. The resulting forest fire was put out with some difficulty despite the wet weather. Almost certainly this was an example of ball-lightning - a rare electromagnetic phenomenon which occurs when electrically charged air forms a white hot ball during a thunderstorm.
Other apparently genuine UFOs turn out to be deliberate hoaxes. In 1962 a 14 year old British schoolboy, Alex Birch, photographed five saucer-shaped objects flying over his home in Sheffield. He sent the photo to the local press, who passed the story on to the Air Ministry and to national media. Soon Alex was being interviewed on radio, televison and by the authorities. He stuck to his story and convinced nearly everyone who spoke to him. Photographic experts found no evidence of trickery or manipulation in the photographic negative.
More than ten years later, Alex admitted that the whole affair had been a hoax. He had produced the photo by painting the “discs” on to his bedroom window and then taking a photo through the window of the scenery beyond. What were really small paintings close up seemed to be large objects far away. Alex claimed to have taken the photo as a joke, but to have become frightened when government officials arrived and so too scared to admit that the photo was a fake.
It is sometimes possible to recognise frauds, advanced technology and unusual natural phenomena for what they are, but not always. There are probably hundred of cases of seemingly baffling UFOs which are perfectly normal things, but for one reason or another remain unidentified.