The manner of indicating distance N. or S. of the Celestial Equator. The maximum possible declination of the Sun is 23° 28' which occurs at the Solstices, when the Sun passes the Tropics (0°) of Cancer and Capricorn, the limit of the pole's greatest inclination from the plane of the Earth's orbit. The first degrees of Aries and Libra have no declination, since at these points the ecliptic intersects the equator. However, planets at this longitude may have declination. (v. Celestial Sphere.)
The declination of a body whose longitude and latitude are known is found by this formula:
1. Radius (10,000): Tangent of Ecliptic (23° 27'):: sine of longitudinal distance from equinox: tangent of Angle A.
2. Cosine of Angle A: cosine (latitude plus/minus 90°- minus Angle A):: cosine of Ecliptic Obliquity (23° 27'): sine of the Declination. (In this equation the latitude is taken from go, if the latitude and longitude are of different denomination; but when of the same denomination they are added, and from this sum Angle A is subtracted.)
The Moon, Mercury, Mars reach a declination of 27° north, and on rare occasions Venus reaches 28°. Jupiter, Saturn, Uranus and Neptune have practically the same declination as the Sun.
