Light pollution

Street light, Over-illumination, Sodium-vapor lamp, Skyglow, Sky brightness, Bortle Dark-Sky Scale, Photometry, Polarized light pollution, International Dark-Sk... » 

Street light, Over-illumination, Sodium-vapor lamp, Skyglow, Sky brightness, Bortle Dark-Sky Scale, Photometry, Polarized light pollution, International Dark-Sky Association, CieloBuio, National Dark-Sky Week, Dark-sky movement «