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Airglow over Auvergne, France Yellow, green and red bands of airglow along Earth's limb as seen from space. Airglow (also called nightglow ) is a faint emission of light by a planetary atmosphere . In the case of Earth's atmosphere , this optical phenomenon causes the night sky never to be completely dark, even after the effects of starlight ...
Paranal Observatory nights. [3] The concept of noctcaelador tackles the aesthetic perception of the night sky. [4]Depending on local sky cloud cover, pollution, humidity, and light pollution levels, the stars visible to the unaided naked eye appear as hundreds, thousands or tens of thousands of white pinpoints of light in an otherwise near black sky together with some faint nebulae or clouds ...
For example, one shot of dark branches covering a sunny meadow give the resemblance of a landscape at night or a starry night sky. [4] Dorsky also oscillated the aperture to create fluctuations in light intensity, which he likened to a musical vibrato. [1] His extreme use of underexposure gives some images the illusion of day for night. [2]
Skyglow (or sky glow) is the diffuse luminance of the night sky, apart from discrete light sources such as the Moon and visible individual stars. It is a commonly noticed aspect of light pollution . While usually referring to luminance arising from artificial lighting , skyglow may also involve any scattered light seen at night, including ...
Nitrogen glow Oxygen glow Electrical discharge in air Particle beam from a cyclotron. Ionized-air glow is the luminescent emission of characteristic blue–purple–violet light, often of a color called electric blue, by air subjected to an energy flux either directly or indirectly from solar radiation.
The Bortle dark-sky scale (usually referred to as simply the Bortle scale) is a nine-level numeric scale that measures the night sky's brightness of a particular location. It quantifies the astronomical observability of celestial objects and the interference caused by light pollution .
Sky brightness refers to the visual perception of the sky and how it scatters and diffuses light. The fact that the sky is not completely dark at night is easily visible. If light sources (e.g. the Moon and light pollution ) were removed from the night sky , only direct starlight would be visible.
It is also called sky radiation, the determinative process for changing the colors of the sky. Approximately 23% of direct incident radiation of total sunlight is removed from the direct solar beam by scattering into the atmosphere; of this amount (of incident radiation) about two-thirds ultimately reaches the earth as photon diffused skylight ...