Search results
Results From The WOW.Com Content Network
Twilight occurs according to the solar elevation angle θ s, which is the position of the geometric center of the Sun relative to the horizon. There are three established and widely accepted subcategories of twilight: civil twilight (nearest the horizon), nautical twilight, and astronomical twilight (farthest from the horizon).
Civil" twilight occurs when the Sun is between 0 and 6 degrees below the horizon. Nearby planets like Venus and bright stars like Sirius are visible during this period. [3] "Nautical" twilight continues until the Sun is 12 degrees below the horizon. [4] During nautical twilight, the horizon is visible enough for navigation. [5] "Astronomical ...
Twilight (both dusk and dawn) is divided into three 6° segments that mark the Sun's position below the horizon. At civil twilight, the center of the Sun's disk appears to be between 1/4° and 6° below the horizon. At nautical twilight, the Sun's altitude is between –6° and –12°. At astronomical twilight, the Sun is between –12° and ...
After sunset the civil twilight sets in, and ends when the Sun drops more than 6° below the horizon. This is followed by the nautical twilight, when the Sun reaches heights of −6° and −12°, after which comes the astronomical twilight defined as the period from −12° to −18°. When the Sun drops more than 18° below the horizon, the ...
Civil, nautical, and astronomical twilight. [3] Dusk is the darkest part of evening twilight. The time of dusk is the moment at the very end of astronomical twilight, just before the minimum brightness of the night sky sets in, or may be thought of as the darkest part of evening twilight. [4]
After sunset, the civil twilight sets in; it ends when the Sun drops more than 6° below the horizon. This is followed by the nautical twilight, when the Sun is between 6° and 12° below the horizon (depth between −6° and −12°), after which comes the astronomical twilight, defined as the period between −12° and −18°. When the Sun ...
Civil" twilight occurs when the Sun is between 0° and 6° below the horizon. Nearby planets like Venus and bright stars like Sirius are visible during this period. [16] "Nautical" twilight continues until the Sun is 12° below the horizon. [17] During nautical twilight, the horizon is visible enough for navigation. [18] "Astronomical" twilight ...
A diagram of a typical nautical sextant, a tool used in celestial navigation to measure the angle between two objects viewed by means of its optical sight. Celestial navigation, also known as astronavigation, is the practice of position fixing using stars and other celestial bodies that enables a navigator to accurately determine their actual current physical position in space or on the ...