Diffuse interstellar band

Diffuse interstellar bands (DIBs) are absorption features seen in the spectra of astronomical objects in our galaxy. They are caused by the absorption of light by the interstellar medium. About 100 bands are seen, in ultraviolet, visible and infrared wavelengths.

The origin of DIBs was unknown and hotly disputed for many years, but currently they seem likely to be due mostly to polycyclic aromatic hydrocarbons and other large carbon-bearing molecules.