(1) Terrestrial or Geographical. The distance of any point on the Earth's surface, E. or W. of Greenwich; measured by geographers in degrees; by astronomers, in hours. (2) Celestial. Longitude in the heavens; the distance between the first point in the zodiac (Aries 0°) and any celestial body, measured along the ecliptic, in degrees. For example, Antares, to an astrologer is in Sagittarius 8°; to an astronomer, L. 248°. Celestial longitude is of two kinds: (a) Geocentric, figured from the earth as the center; now chiefly used by astrologers to indicate the zodiacal positions of the planets, but rarely used by astronomers, and in the Nautical Almanac is given only for the Sun and Moon. (b) Heliocentric, figured from the Sun as the center. Longitude as used in astronomical terminology is given in degrees from 1 to 360. Thus Long. 125° becomes 5° Leo; 4 signs of 3° degrees each = 120° - hence 5° in the next or 5th Sign. v. Celestial Circle.
Geographical Longitude is measured E. and W. from the Meridian of Greenwich observatory; Celestial Longitude from the Meridian of the Vernal Equinox: 0° Aries.
