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In astronomy, declination (abbreviated dec; symbol ''δ'') is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle. Declination's angle is measured north or south of the celestial equator, along the hour circle passing through the point in question.〔 〕 The root of the word ''declination'' (Latin, ''declinatio'') means "a bending away" or "a bending down". It comes from the same root as the words ''incline'' ("bend toward") and ''recline'' ("bend backward").〔 〕 ==Explanation== (詳細はlatitude, projected onto the celestial sphere, and hour angle is likewise comparable to longitude.〔 , at (Google books ) 〕 Points north of the celestial equator have positive declinations, while those south have negative declinations. Any units of angular measure can be used for declination, but it is customarily measured in the degrees ( ° ), minutes ( ' ), and seconds ( " ) of sexagesimal measure, with 90° equivalent to circle. Declinations with magnitudes greater than 90° do not occur, because the poles are the northernmost and southernmost points of the celestial sphere. An object at the * celestial equator has a declination of 0° * north celestial pole has a declination of +90° * south celestial pole has a declination of −90° The sign is customarily included whether positive or negative. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Declination」の詳細全文を読む スポンサード リンク
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