What is Black Moon Lilith?
In many modern astrology charts, “Black Moon Lilith” means the mean lunar apogee: the average direction of the far end of the Moon’s orbital axis as viewed from Earth. It is a calculated point, not a visible moon or planet.
The opposite end of the same mean axis is the mean lunar perigee. The lunar apogee and perigee are astronomical orbit concepts. Mythological Lilith and later astrological interpretations are separate traditions; the calculated longitude alone does not establish personality or events.
How this calculator obtains the longitude
The calculation starts with Jean Meeus’s polynomial for the Moon’s mean longitude of perigee, using Terrestrial Time centuries from J2000. It adds 180° for the opposite apsidal direction and projects that direction from the Moon’s mean orbit, inclined about 5.1454° to the ecliptic, into the mean ecliptic and equinox of the date. The mean lunar node supplies the intersection of the two planes.
The projection matters. Simply adding 180° to the unprojected polynomial can miss the printed mean-apogee position by several arcminutes. The result here is rounded to the nearest arcminute for the sign-and-degree display. The underlying decimal longitude is shown to four places for comparison, not as a promise of four-place accuracy.
Why another chart may differ
This page uses a compact Meeus-based approximation and is therefore not a Swiss Ephemeris clone. In spot checks at selected 1800–2100 dates, the model was within roughly one arcminute of Swiss Ephemeris mean-apogee output; that is a comparison sample, not a bound for every date. A different UTC offset, time scale, zodiac frame, or choice of “true”/osculating versus mean apogee can also change a result.
This tool deliberately does not calculate or label that osculating point. Asteroid 1181 Lilith and a historical hypothetical “second moon” are different objects and are not used here.