Most casual observers would consider the entire sky already fully dark even when astronomical twilight is just beginning in the evening or just ending in the morning, and astronomers can easily make observations of point sources such as stars, but faint diffuse items such as nebulae and galaxies can only be properly observed beyond the limit of astronomical twilight.Theoretically, the dimmest stars ever visible to the naked eye-those of the sixth magnitude-will appear in the evening once the sun falls more than 18° below the horizon (i.e.During this period there is enough light from the sun that artificial sources of light may not be needed to carry on outdoor activities.
The brightest stars appear during the civil twilight, as well as planets, such as Venus, which is known as the 'morning star' and/or 'evening star'.
Nautical twilight Nautical twilight is the time when the center of the sun is between 6° and 12° below the horizon.
In general, nautical twilight is the point where navigation via the horizon at sea is no longer possible.
At the beginning of nautical twilight in the morning (nautical dawn), or at the end of nautical twilight in the evening (nautical dusk), under good atmospheric conditions and in the absence of other illumination, general outlines of ground objects may be distinguishable, but detailed outdoor operations are not possible, and the horizon is indistinct.
Nautical twilight has military considerations as well.If you wish to file for unemployment in CA, you must have discontinued employment through no fault of your own in most circumstances.