A well-known folklore motif is the lone ball of flame that is seen repeatedly moving around a haunted forest, graveyard, mountain, or body of water. Land-based ghost lights have often been attributed to spirits or witches, while on the sea they are described as eerily lit phantom ships. In the United States, the most famous are the Ozark Spook Light of Missouri and Oklahoma and the Brown Mountain Lights of North Carolina. In Canada, the fire ships of Chaleur Bay and the Northumberland Strait are prominent.
Stripped of its supernatural trappings, the ghost light does have a basis in fact. Modern observations of the Ozark Spook Light have been shown to be peculiar refractions of car headlights on a distant road, although the light has a tradition that may precede the local advent of automobiles. The small lights that flicker around swampy areas are known as will-o’-the-wisp or ignis fatuus and are said to be spontaneously ignited gases generated by decaying vegetation. This swamp gas made national headlines in 1966 when astronomer J. Allen Hynek, then a consultant to the Air Force on UFOs, issued a statement to the press suggesting that recent UFO sightings in Michigan were swamp gas. But true swamp gas, usually methane, does not have sufficient energy, duration, or maneuverability to account for ghost lights, which seem to be an electrical phenomenon akin to earthquake lights or ball lightning.