The different components of the light of the night sky are integrated along the line of sight of the observer located on planet Earth or on the near Earth’s environment. They encompass a huge scale of distances, ranging from hundreds of kilometers in the Earth’s atmosphere (airglow lines, bands and continuum), to astronomical units in the interplanetary medium (zodiacal light continuum), thousand of light years in the interstellar medium (diffuse galactic light and integrated starlight) and even much more in the extragalactic universe (extragalactic background radiation).