descending node
greek: καταβιβάζων (katabibazōn) · latin: nodus descendens / cauda draconis · arabic: ذنب التنين (dhanab al-tinnīn, 'tail of the dragon') · sanskrit: Ketu
Definition
The point at which the orbital plane of the Moon (or of a planet) crosses the ecliptic from north to south — that is, the body, having been north of the ecliptic, is moving downward across it. The Moon's descending node is the more commonly cited of the two and is known in tradition as the South Node, Ketu (in Vedic astrology), or 'the Tail of the Dragon' (cauda draconis). It always lies opposite the ascending node and shifts retrograde along the ecliptic, completing one full circuit in about 18.6 years.
In Tradition
Across Babylonian, Hellenistic, and Western tradition, the nodes are the points where the Moon's path crosses the Sun's path — and therefore the only places where eclipses can occur. Babylonian lunar theory distinguishes them by the sign of latitude change rather than by a separate symbolic name; the more interpretive tradition (medieval Arabic-Latin, modern Western, Vedic) develops a fuller astrological reading of the two nodes as a polarity axis.
In Practice
Astrologers track the descending node as one half of the lunar nodal axis. In eclipse work, a New or Full Moon within a few degrees of either node produces an eclipse: solar at the conjunction, lunar at the opposition. In natal interpretation the descending (south) node is read as a point of release, depletion, or already-mastered material — sign and house of the south node showing where energy flows out, and the north node the corresponding intake. Transits to the natal nodal axis (including the nodal return at 18-19 years) reliably mark themes of fated encounter and turning. Practitioners specify whether they are using the mean node (smoothed) or the true node (oscillating).
Historical Origin
Babylonian lunar theory in the Late-Babylonian mathematical-astronomical period (Rochberg, The Heavenly Writing Ch. 4) already distinguishes ascending and descending crossings of the lunar path with the ecliptic and tracks the latitude function (Column E of the lunar ephemerides). The interpretive doctrine of the nodes as Head and Tail of the Dragon (Caput / Cauda Draconis) reaches Western astrology through the Arabic transmission and is canonical from Bonatti and the medieval Latin tradition forward.
Etymology
Origin: Latin. Meaning: The descending knot.
Further Reading
- Francesca Rochberg, The Heavenly Writing
- Bernadette Brady, Eclipses and the Lunar Nodes
- Demetra George, Asteroid Goddesses