Dusk

Dusk occurs at the darkest stage of twilight, or at the very end of astronomical twilight after sunset and just before night. Pre-dusk, during early to intermediate stages of twilight, there may be enough light in the sky under clear conditions to read outdoors without artificial illumination, but at the end of civil twilight, when Earth rotates to a point at which the center of the Sun is 6° below the local horizon, artificial illumination is required to read outside. The term dusk usually refers to astronomical dusk, or the darkest part of twilight before night begins.Seattle, Washington during Nautical twilightCivil twilight in Porto Covo, west coast of PortugalAstronomical twilight as seen from a plane windowMagere Brug Amsterdam - Astronomical twilightView from Ibirapuera Park, São Paulo, Brazil, at Civil twilightTrees silhouette dusk skyCivil twilight in Albi, FranceAmoudi Bay, Santorini, at dusk.Nautical twilight in Vancouver, British Columbia, Canada Dusk occurs at the darkest stage of twilight, or at the very end of astronomical twilight after sunset and just before night. Pre-dusk, during early to intermediate stages of twilight, there may be enough light in the sky under clear conditions to read outdoors without artificial illumination, but at the end of civil twilight, when Earth rotates to a point at which the center of the Sun is 6° below the local horizon, artificial illumination is required to read outside. The term dusk usually refers to astronomical dusk, or the darkest part of twilight before night begins. The time of dusk is the moment at the very end of astronomical twilight, just before the minimum brightness of the night sky sets in, or may be thought of as the darkest part of evening twilight.But technically, the three stages of dusk are as follows.