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[nuh-byoo-lee-uh m] /nəˈbyu li əm/
noun, Astronomy
a hypothetical element once thought to be present in emission nebulae because of certain unidentified spectral lines, now known to be forbidden transitions of oxygen and nitrogen ions.
1895-1900; nebul(a) + -ium Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for nebulium
  • These lines defied explanation for over fifty years, lending speculation they were due to a new element, which was named nebulium.
Encyclopedia Article for nebulium

hypothetical chemical element whose existence was suggested in 1868 by the English astronomer Sir William Huggins as one possible explanation for the presence of unidentified (forbidden) lines (at 3,726, 3,729, 4,959, and 5,007 angstroms wavelength) in the spectra of gaseous nebulae. In 1927 the American physicist and astronomer Ira S. Bowen correctly determined that the common elements oxygen and nitrogen ionized (i.e., electrically charged) under conditions unobtainable on Earth are responsible for these spectral lines. See also forbidden lines.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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