methane (CH4)

methane molecule

The magnetotatic bacterium Magnetospirillum magnetotacticum.

Methane (CH4) is a colorless, odorless, inflammable gas, known commonly as marsh gas or fire damp. It is the simplest hydrocarbon and the first member of the alkane series. It is the main constituent of natural gas, is released by methanogenic microbes and volcanic vents, and forms from decaying matter and in coal mines. With air it makes an explosive mixture. Methane is used as a fuel and in the manufacture of other chemicals.


Methane occurs in the atmospheres of the gas giant planets and in the atmosphere and on the surface of Saturn's largest moon, Titan. It has also been detected in small quantities in the atmosphere of Mars (see methane on Mars).


Testing is underway of a methane rocket engine that might eventually be used on deep space missions.


melting point -182.5°C (-296.5°F)
boiling point -161°C (-263.2°F)



Also known as jack-o'-lantern, this is mysterious light sometimes seen at night in marshy areas. It is not well understood but is thought to be due to the spontaneous combustion of methane. Its elusive nature makes it the basis for various superstitious beliefs.