swamp gas

== English == === Etymology === (hydrogen sulfide): So called because it is often emitted from wetlands such as swamps as a result of anaerobic bacteria, and is responsible for their foul “rotten egg” odor. (ufology): An explanation given by then-skeptic J. Allen Hynek for an alleged UFO sighting in Michigan near Lake Huron in 1966. === Pronunciation === === Noun === swamp gas (uncountable) (literally) Gases emitted from a swamp. Synonyms: bog gas, marsh gas, biogas (inorganic chemistry, colloquial) Hydrogen sulfide. Synonym: rotten egg gas (ufology, sarcastic) A skeptical explanation that is provided in order to debunk a UFO sighting that a believer regards as ludicrous, illogical or disingenuous. Synonyms: weather balloon, pelicanist ==== See also ====