Chart basics · Intermediate
Ecliptic longitude
Also called celestial longitude, zodiacal longitude
A position measured along the ecliptic from 0° at the March equinox point up to 360°.
Every position in a Western chart is an ecliptic longitude. Tropical astrology cuts the 360° into twelve 30° signs starting at the March equinox point, so 45° of longitude is 15° Taurus. This site uses apparent longitude, measured from the true equinox of the date, as seen from Earth's centre.
- How it is worked out
- Sign = floor(longitude ÷ 30); degree in sign = longitude − 30 × sign.
Sources
- Swiss Ephemeris documentation (Astrodienst): house systems, nodes and calculation conventions (opens in a new tab) technical
- International Astronomical Union: Constellations (FAQ) (opens in a new tab) academic
Written for Cool Moon Facts in its own words. An astrology source documents what astrologers believe or practise; it does not establish that astrology works.