The Mystery of Ghostly Will-o'-the-Wisps May Finally Be Solved

"Some call them will-o'-the-wisps; others call them ignis fatuus, Latin for foolish fire. Whatever the name, for centuries people have reported seeing these eerie, faint blue flames hovering over marshes, bogs and other wetlands. Various cultures interpreted the ephemeral aberrations as fairies, ghosts or spirits. Scientists have offered a different explanation: they form when methane and other gases from decaying material react with oxygen and briefly ignite, producing a flamelike glow."

"Although will-o'-the-wisps are not actual flames and occur at ambient temperatures, they still have to ignite somehow. The source of that ignition has been unknown. Now a new paper published in Proceedings of the National Academy of Sciences USA seems to provide an answer: microlightning, or tiny, spontaneous sparks of electricity that occur because of differences in charges on water droplets' surfaces."

"says Richard Zare, a physical chemist at Stanford University and senior author of the findings. In fact, the phenomenon we foundrelated to how chemistry can be driven at interfacesis profound. Water is neutral, which means it doesn't typically carry electric charge. But as early as 1892, scientists have noted that tiny droplets of water in the air can be positively or negatively charged in situations such as waterfall spray or fog."

Will-o'-the-wisps are faint blue glows seen over marshes and wetlands that arise when methane and other gases from decaying material react with oxygen and briefly ignite. The ignition mechanism can be microlightning: tiny spontaneous electrical sparks produced by charge differences on the surfaces of water droplets. Those charged droplets form when water bubbles containing methane rise and burst at the marsh surface, releasing droplets with differing charges. The resultant sparks can ignite the released methane, producing the flamelike luminescence at ambient temperatures. Tiny droplets in sprays, fog or waterfall mist can carry positive or negative charge, enabling such sparks.

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