What is Light Pollution?

"Light Pollution" is a form of environmental degradation in which excessive artificial outdoor lightings, such as street lamps, neon signs, and illuminated signboards, affect the natural environment and the ecosystem. The wasteful light emitted directly upwards or reflected upwards from poorly-designed artificial light sources can be scattered by clouds, fog, and pollutants like suspended particulates in the atmosphere. The night sky is thus brightened, leading to a reduced number of stars visible in the sky due to a decrease of the light contrast.