Descendant

The Descendant is the point opposite the Ascendant, the degree of the ecliptic setting on the western horizon, and it is the cusp of the seventh house. Its significations are the other party: marriage and the spouse, business partners, the open adversary, and in horary work the person on the other side of the question. The classical texts often treat the seventh house rather than the Descendant as a point in its own right, and the emphasis on the four angles as sensitive degrees is more characteristic of modern practice than of the older sources, though the angles themselves are fundamental to both. Being derived from the Ascendant by simple opposition, the Descendant carries the same dependence on an exact birth time and place, and the same rapid daily motion through the zodiac.

In synastry, the comparative reading of two charts against each other, the Descendant is one of the points most commonly checked for a partner's planets falling close to it, on the reasoning that the seventh-house cusp is the natural signifier of what one is drawn to seek in another person; this specific synastric use of the Descendant is a twentieth-century development built on the classical seventh-house doctrine rather than a technique documented in the Hellenistic or medieval sources themselves, which discuss the seventh house's relationship significations without this particular comparative method.

The descendant is the point of the ecliptic opposite the ascendant, 180 degrees away by definition. It shares the ascendant's dependence on time, longitude and latitude, its full circuit in one sidereal day, its average of one degree every 3 minutes 59 seconds, and its very uneven rate.

Because it is defined as the opposite point rather than computed separately, no house system disagrees about it. That is unusual: in a chart where the second, third, fifth, sixth, eighth, ninth, eleventh and twelfth cusps can lie many degrees apart between systems, and where whole-sign and equal houses part company with the quadrant systems even about the Midheaven, the descendant is fixed by the ascendant and nothing else.

There is one nicety worth stating because it is commonly glossed over. The descendant is a point on the ecliptic, and a planet is on the descendant when its ecliptic longitude matches. That is not the same as the planet actually setting. A body with ecliptic latitude, which means every body except the Sun, sets a little before or after the moment its longitude reaches the descendant, and for the Moon, whose latitude runs to about five degrees, or for a steeply inclined asteroid, the difference can amount to several minutes of clock time and occasionally more.

Longitude is the working coordinate of the tradition, and it is a projection, not a sighting.

As the western angle, the Descendant complements the eastern Ascendant, and like the other three angles it was a fixture of Hellenistic horoscopy from its earliest surviving technical manuals; Firmicus Maternus lists it among the cardines in his fourth century Mathesis, and quadrant based house division, worked out fully in this Hellenistic period, uses the Ascendant-Descendant axis together with the Midheaven-Imum Coeli axis to divide a chart into its four quarters.

The Descendant is abbreviated DC or, less often, Dsc in chart notation, mirroring the AC/Asc pairing used for the Ascendant. The Greek kentron behind the Latin cardo could mean either a sharp goad, the kind used to drive an animal, or the pivot at the center of a turning wheel, and both senses were applied to the four angles as the points that seem to drive the chart's daily rotation. Because it sits at exactly 180 degrees from the Ascendant, its position was never calculated independently once the rising degree was known, unlike the Midheaven, which requires its own separate reference to the meridian. On the now standard circular wheel chart the Descendant sits opposite the Ascendant at roughly the three o'clock position, a diagramming convention that replaced the older square horoscope format, itself used across Western, Indian and Chinese astrology for centuries, only around the nineteenth century.