‘Microlightning’ between tiny methane bubbles may explain ghostly glow of will

A high-speed camera captures flashes between methane-air bubbles in a container of water. This "microlightning" is thought to produce the eerie flames of a will-o'-the-wisp. Richard Zare

Hovering blue flames that flicker over bogs and marshes have inspired ghostly folktales for centuries. Known as “will-o’-the-wisp,” “jack-o’-lantern,” “corpse candle” and “ignis fatuus” (“foolish fire” in Latin), the global phenomenon has a spine-tingling history. But its origins could now have a scientific explanation: tiny flashes of lightning that ignite microscopic bubbles of methane.

Scientists have long suspected that the will-o’-the-wisp’s spectral glow came from a chemical reaction in gases released by decaying organic matter. Methane, which is odorless, colorless and highly flammable, is one s