Dawns

Dawn is the period in the early morning when light first appears as the Sun rises toward the horizon. It marks the transition from night to day and ends with sunrise, when the Sun’s upper edge clears the horizon.

There are several conventional stages defined by the Sun’s position below the horizon. Civil dawn begins when the Sun is 6 degrees below the horizon, bringing enough daylight for most outdoor activities. Nautical dawn occurs at 12 degrees below, when the horizon at sea becomes discernible for navigation. Astronomical dawn begins at 18 degrees below, after which the sky is bright enough that most astronomical observations are possible but stars are still faint.

The timing and duration of dawn vary with latitude and season. Near the equator dawns are relatively quick, while at high latitudes dawn can stretch into lengthy twilight, especially in autumn and spring. In polar regions, zones of twilight may persist for weeks, and at certain times of year there may be no true dawn at all or conversely a continuous dawn-like light during the midnight sun.

Dawn has ecological and cultural significance. Many species exhibit activity patterns tied to dawn, including the dawn chorus of birds. Plants begin photosynthesis as light increases. Culturally, dawn is associated with renewal and is referenced in literature, art, and folklore; the term derives from Old English dagian, with related terms such as aurora in other languages and mythologies surrounding the Greek goddess Eos or the Roman Aurora.

Practically, dawn times are calculated from solar geometry and local geography and are used in scheduling, aviation, navigation, and daily life.