Astronomy Glossary
There are currently 3 names in this directory beginning with the letter D.
D
declination
In the equatorial coordinate system, the celestial equivalent of terrestrial latitude. Coordinates north of the celestial equator are measured in positive degrees from 0° to 90°, while coordinates to the south are measured in negative degrees. See also right ascension.
(a) Angular distance above (positive) or below (negative) the celestial equator. One of the co-ordinates, with right ascension, that defines the position of a heavenly body.
(b) Position on the sky in a north-south direction. Lines of declination are the celestial equivalent of latitude on Earth. Compare right ascension.
(c) Astronomical coordinate. Equivalent to latitude. The angle in degrees above or below the Celestial Equator, i.e. the projection onto the sky of the Earth's equator. Range of declination is from from zero to ± 90°.
(d) Angular distance on the celestial sphere north or south of the celestial equator. It is measured along the hour circle passing through the celestial object. Declination is usually given in combination with right ascension or hour angle.
(e) Angular distance north (+) or south (-) of the celestial equator to some object, measured in degrees, minutes, and seconds of arc along an hour circle passing through the object. Declination is analogous to latitude on the Earth's surface.
(a) Angular distance above (positive) or below (negative) the celestial equator. One of the co-ordinates, with right ascension, that defines the position of a heavenly body.
(b) Position on the sky in a north-south direction. Lines of declination are the celestial equivalent of latitude on Earth. Compare right ascension.
(c) Astronomical coordinate. Equivalent to latitude. The angle in degrees above or below the Celestial Equator, i.e. the projection onto the sky of the Earth's equator. Range of declination is from from zero to ± 90°.
(d) Angular distance on the celestial sphere north or south of the celestial equator. It is measured along the hour circle passing through the celestial object. Declination is usually given in combination with right ascension or hour angle.
(e) Angular distance north (+) or south (-) of the celestial equator to some object, measured in degrees, minutes, and seconds of arc along an hour circle passing through the object. Declination is analogous to latitude on the Earth's surface.
deep-sky object (DSO)
Any astronomical object that is not an individual star or an object within the Earth's Solar System. The classification is used mostly in amateur observational astronomy to distinguish faint objects in the night sky such as star clusters, nebulae, and galaxies.
