Dusk and sunset are both beautiful times of day that mark the transition from daylight to darkness. While often used interchangeably, they represent distinct phases. Sunset refers to the moment the sun dips below the horizon. Dusk, on the other hand, is the period of twilight that follows sunset, characterized by indirect sunlight scattering in the upper atmosphere. Dusk lasts until the sun is 18 degrees below the horizon, marking the end of civil twilight.