<P> 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 . </P> <P> 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"). </P>

What do we call the celestial coordinate that is similar to the earths longitude coordinate