meters to a meter or so in diameter. It has been variously reported as white, blue, yellow, red, orange, or green in color. It only lasts a short time, usually less than 5 seconds, but in a small number of cases it reportedly lasted over a minute. It may descend, hover, or move horizontally, but it has rarely been reported to rise. It sometimes has a strong odor, but not always. It either vanishes silently or with a loud explosion. There are a few purported photographs of ball lightning, but it's difficult to determine what the photos actually depict. Almost all of the evidence for the phenomenon is anecdotal, consisting of sighting reports from a variety of witnesses. There are many theories as to how ball lightning is formed, but none that satisfactorily explains its behavior. The most popular theory is that it is composed of a plasma contained within a magnetic field. Another theory is that it is a cloud of a common gas such as methane that has been ignited by a normal lightning strike. The latter theory, however, is at odds with its reported behavior. Clouds of ignited methane would rise from the ground, rather than drop from the sky. Ball lightning has occasionally been used as an explanation for UFO sightings. As such, it has not been a very successful explanation because the reported behavior of ball lightning is not like that of reported UFOs, not to mention that very few UFO sightings occur during thunderstorms. One of the most interesting things about ball lightning is its similarity to the UFO phenomenon. In both we have a phenomenon whose appearance we can't predict and whose origin we can't explain. Science has, however, reluctantly come to accept ball lightning. Not so with UFOs. What's the difference? Skeptic Robert Sheaffer briefly touches on the comparison between ball lightning and UFOs in his recent book, UFO Sightings: The Evidence. He does so, in the context of jealous phenomena. He begins by defining jealous phenom...
