Space Travel
19, May, 2012

Space exploration began with the launch of Sputnik and Astrophysics was born as the application of physics to the phenomena observed by Astronomy, which etymologically means laws of the stars.

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Term Definition
Emission Line Star
Any star that exhibits emission lines in its spectrum in addition to or in place of the more typical absorption lines. The symbol e in a spectral type e.g. B5e signifies the presence of emission lines. Wolf-Rayet stars, the hottest of all, have totally emission line spectra. Emission lines occur in the spectra of certain O stars and B stars and also, at the cooler end of the range, in some M stars and cool variable Mira stars.