View source for Hydrogen-Alpha line

The Hydrogen Alpha (Hα) line is a characteristic emission line in the red part of the visible spectrum, and is created when the electron of a hydrogen atom drops from the third to the second orbit (N=3 and N=2) and the energy difference between the orbits is emitted as electromagnetic radiation. The wavelength at which this occurs is 656&nbsp;nm. Because hydrogen is the most abundant element in the universe this is often the brightest emission line in interstellar space. Because the N=3 to N=2 transition often occurs where hydrogen is being ionised, such as in the corona of a star, the Hα line is often used by astronomers to measure [[redshift]]. [http://www.astronomyknowhow.com/hydrogen-alpha.htm]
[[Category:Physics]]