Editing Spectral line (section)

==Spectral lines of chemical elements==
{{See also|Hydrogen spectral series}}
[[File:Spectrum of blue sky.svg|thumb|right|upright=1.4|Absorption lines for air, under indirect illumination, so that the gas is not directly between source and detector. Here, [[Fraunhofer lines]] in sunlight and [[Rayleigh scattering]] of this sunlight is the "source." This is the spectrum of a blue sky somewhat close to the horizon, looking east with the sun to the west at around 3–4 pm on a clear day.]]

===Bands===
The phrase "spectral lines", when not qualified, usually refers to lines having wavelengths in the [[visible spectrum|visible band]] of the full [[electromagnetic spectrum]]. Many spectral lines occur at wavelengths outside this range. At shorter wavelengths, which correspond to higher energies, [[ultraviolet]] spectral lines include the [[Lyman series]] of [[hydrogen]]. At the much shorter wavelengths of [[X-ray]]s, the lines are known as [[characteristic X-ray]]s because they remain largely unchanged for a given chemical element, independent of their chemical environment. Longer wavelengths correspond to lower energies, where the [[infrared]] spectral lines include the [[Hydrogen spectral series#Paschen series (Bohr series, n′ = 3)|Paschen series]] of hydrogen. At even longer wavelengths, the [[radio spectrum]] includes the [[Hydrogen line|21-cm line]] used to detect neutral hydrogen throughout the [[Hydrogen line#In cosmology|cosmos]].