User:Physchim62/Helium
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Revision as of 19:13, 17 March 2010 by Physchim62 (talk | contribs) (Created page with ''''Helium''' (symbol: '''He''') is a chemical element, the lightest of the noble gases. ==History== Helium is the only element to have been discovered extraterrestrially…')
Helium (symbol: He) is a chemical element, the lightest of the noble gases.
History
Helium is the only element to have been discovered extraterrestrially before being found on Earth, specifically in the Sun. A bright yellow spectral line (587.49 nm) was first observed by French astronomer Pierre Janssen during the eclipse of 18 August 1868, which Janssen observed from Guntur in India, and independently by Norman Lockyer in London on 20 October 1868.[1] Lockyer, together with English chemist Edward Frankland, showed that the line could not be explained by any known element, and proposed the name helium, from the Greek ἥλιος (helios, the Sun).
References
- ↑ Cortie, A. L. Sir Norman Lockyer, 1836–1920. Astrophys. J. 1921, 53 (4), 233–48, <http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1921ApJ....53..233C&data_type=PDF_HIGH&whole_paper=YES&type=PRINTER&filetype=.pdf>.
