Dawn - online puzzles

Dawn, from an Old English verb dagian: "to become day ", is the time that marks the beginning of twilight before sunrise. It is recognized by the appearance of indirect sunlight being scattered in the atmosphere, when the centre of the Sun 's disc reaches 18° below the horizon. This dawn twilight period will last until sunrise (when the Sun 's upper limb breaks the horizon ), as the diffused light becomes direct sunlight.