Gas (interstellar)
Diffuse atoms or molecules of gas in interstellar space, making up about 99% of the interstellar medium. Depending on density, the number of atoms range from 0.1 to 1 atoms per cubic centimetre of normal space, with up to 1000 per cubic centimetre in gas clouds. About 75% is hydrogen, the remainder being helium, with traces of other elements.
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Development Notes
Text by M. Alan Kazlev
Initially published on 01 November 2001.