U.F.O. stands for "Unidentified Flying Object". The majority of UFOs can be easily explained as weather balloons or flocks of birds, but each year there are many sightings of objects in the sky that cannot be explained. The legend of UFOs has developed it's own unique legion of followers who believe that these unidentified flying objects are spacecraft from distant planets.
Dr. J. Allen Hynek penned the scientifically accepted term for UFO:
UFO sightings appear all through recorded history, Alexander the Great saw two airborne "silver shields" in 329 BC. In 1235 the Japanese army of Oritsume saw the "mysterious lights in the sky" and the British people reported many "mystery airships" from 1909 through 1913.
The modern day fascination with UFOs can be traced to American businessman Kenneth Arnold (see photo, inset) who claimed to see nine bright objects flying at "incredible speed" on June 24, 1947, near Mount Rainier, Washington. This led to the golden age of UFO stories, books and films like The Day the Earth Stood Still and Forbidden Planet . Around this time the first UFO-related spiritual sect also appeared, The Aetherius Society. In the 1970's and 80's, the films Close Encounters of the Third Kind and E.T. opened wide the mind of Americans in regards to UFOs, as did popular television series' like Star Trek. In 2002, a Roper poll found that 56% of Americans thought UFOs were real craft and 48% believed that UFOs had visited the Earth.