True-colour pictures have a distinctly pink colour from the combination of visible Balmer lines. This splitting is called fine structure was found also that excited electrons. The 1888 physicist Johannes Rydberg generalized the Balmer equation for all transitions of hydrogen. The Balmer lines appear in a spectrum as emission lines and absorption. Stellar spectra is often mixed in with another absorption line. The H-zeta line is mixed similarly in with a neutral helium line. This Bohr model picture of the orbits has some usefulness for visualization.
The 2p level is split by the spin-orbit effect into a pair of lines.