An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

One of the twilight phases when the Sun's center lies between 12 and 18 degrees below the horizon. Astronomical twilight is followed or preceded by → nautical twilight. Most stars and other celestial objects can be seen during this phase. However, some of the fainter stars and galaxies may not be observable as long as the Sun is less than 18 degrees below the horizon. See also → civil twilight.

→ astronomical; → twilight.