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declination This is a fundamental term and concept in celestial navigation. It is the latitude of the geographical position of any celestial body. Stars have very nearly constant declinations; they can have any value between N 90° and S 90°. Declinations of individual stars have a very small drift over the years due to precession of the equinoxes and proper motion. The sun's declination varies slowly throughout the year from N 23.45° to S 23.45°, at a maximum rate of 1' per hour. The declinations of the moon and planets vary in a more complex manner between about N 30° to S 30°. The N,S label is conventionally placed before the declination to distinguish it from geographic latitude, which is written with the label after the value, ie a star with declination N 19º passes over all points on earth once a day that have latitude 19º N. See Geographical Position and see d-value. See also Tricky Terms in Navigation. Abbreviation:  dec

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