Nautical Twilight is a term which designates the sun's position relative to the horizon. It happens twice per day, once in the morning, and once in the evening. Nautical twilight occurs when the geometric center of the sun is 12 degrees below the horizon. It is the time between Civil Twilight (6 degrees) and Astronomical Twilight (18 degrees).
The time between between-times...
As described by the National Weather Service:
"...In general, the term nautical twilight refers to sailors being able to take reliable readings via well known stars because the horizon is still visible, even under moonless conditions.Absent fog or other restrictions, outlines of terrestrial objects may still be discernible, but detailed outdoor activities are likely curtailed without artificial illumination."
During nautical twilight it is difficult for the eye to discern detail, and shadows can play tricks on the mind. It is the time of magic...a tear in the veil.
Not only is it mystical in nature, but it serves a special purpose for those highly skilled operators around the world. Nautical twilight is the time of the raid. The time in which the enemy would have a difficult time seeing the forces about to wreck his world.
The DoD has a specific term for it; Begin Morning Nautical Twilight (BMNT)
"The start of that period where, in good conditions and in the absence of other illumination, the sun is 12 degrees below the eastern horizon and enough light is available to identify the general outlines of ground objects and conduct limited military operations."
Nautical Twilight Press honors both the practical and magical purposes for its namesake and seeks to find the balance between them both.