The visible line spectrum emitted by hydrogen. The wavelengths of the lines form a series, the formula of which was established by Balmer ( 1885 ).

A distinct pattern of emission or absorption spectral lines that are caused by the transition of electrons to the n=2 energy level of hydrogen. These spectral lines appear at visible wavelengths, and since stars are mostly composed of hydrogen, the Balmer series of spectral lines is one of the most prominent features in the visible spectrum of a star. The first four Balmer lines of the Balmer series are: H-alpha: 656.3 nm (red) H-beta: 486.1 nm (green-blue) H-gamma: 434.0 nm (blue) H-delta: 410.1 nm (blue-violet) See also Lyman series spectrum

The Balmer series or Balmer lines in atomic physics, is the designation of one of a set of six different named series describing the spectral line emissions of the hydrogen atom.