Beginning/Ending of civil twilight is defined as the instant in the morning/evening, when the center of the sun is at a depression angle of six degrees (6°) below an ideal horizon. At this time in the absence of moonlight, artificial lighting or adverse atmospheric conditions, the illumination is such that large objects may be seen but no detail is discernible. The brightest stars and planets can be seen and for navigation purposes at sea, the sea horizon is clearly defined.
The brightest stars and planets can be seen and for navigation purposes at sea, the sea horizon is clearly defined.