This article is from the Ghost Stories FAQ, by obiwan obiwan@best.com with numerous contributions by others.
Will o' the wisps are a natural phenomenon that never the less
appear ghostly in nature. The wisps, which are actually ignited
pockets of swamp gas, hover over swamps and swampy areas and glow
blue. They can move (carried by breezes and air currents), and many
observers have noted that the wisps seem to mimic a person's
movements... when the observer moves forward, so does the wisp. Will
o' the wisps can appear as one glowing ball or as many tiny flickers.
Will o' the wisps have also been called such fanciful names as
"corpse candles", "fox fire", and "elf light". The phenomenon is
also knows as "ignis fatuus", which means "foolish fire". Some
believe the mysterious floating lights to be portents of bad luck
or even death. Researchers believe that many people have mistaken
will o' the wisps for the ghostly lanterns of trains and/or their
long-dead conductors.
 
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