Night is the period of time between the sunset and the sunrise when the Sun is below the horizon. This occurs after dusk. The start and end times of a night vary based on factors such as season, latitude, longitude and timezone. Night is also the period when astrophotography can take place, recording images of astronomical objects and large areas of the night sky.
At any given time, one side of the planet Earth is bathed in light from the Sun (the daytime) and the other side of the Earth is in the shadow caused by the Earth blocking the light of the Sun. This shadow is what we call the darkness of night. Natural illumination is still provided by a combination of moonlight, planetary light, starlight, diffuse zodiacal light, gegenschein, and airglow. In some circumstances, bioluminescence, aurorae, and lightning can provide some illumination. The glow provided by artificial illumination is sometimes referred to as light pollution because it can interfere with astrophotography, observational astronomy and ecosystems.
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