An Etymological Dictionary of Astronomy and Astrophysics

The portion of the → electromagnetic radiation
that can be seen by the human → eye. The → wavelengths extend from about 400 nm (violet) to 750 nm (red). The wavelengths of various colors of the visible spectrum are as follows: → violet: 390-455 nm; → blue: 455-492 nm; → green: 492-577; → yellow: 577-597; → orange: 597-622; → red: 622-780 nm.

See also: → visible; → light.