What is dusk definition?

Dusk is the time period immediately following sunset and before nightfall. During dusk, the sky gradually darkens, and colors in the sky change from bright oranges and pinks to shades of blue and violet. The transition from sunset to dusk occurs because the sun has completely disappeared below the horizon but the scattering of light in the Earth's atmosphere still illuminates the sky. The duration of dusk varies depending on the location and time of year. In general, dusk lasts for about 20 to 30 minutes in most places but can be up to 45 minutes in areas that are farther from the equator. It is during dusk that many animals, including birds and insects, begin their evening activities.