Vertex

The Vertex is the point where the prime vertical, the great circle passing through the east and west points of the horizon and the zenith, intersects the ecliptic in the western half of the chart; the opposite point is the Anti-Vertex. It is a calculated point of the same family as the angles, depending on the exact time and geographic latitude of the chart, and it moves quickly. Its introduction into astrological practice is generally credited to L. Edward Johndro in the middle of the twentieth century, and it is read by those who use it as a point of fated encounter, of meetings that arrive from outside one's own initiative, often in synastry between two charts. The dating is worth stating: this is modern technique, not traditional. The name is also shared with a fixed-star entry for the Andromeda Galaxy, which is an entirely different thing.

Johndro worked largely outside the astrological mainstream of his time, publishing through his own small press, and the Vertex remained a minor, specialist technique for decades after its introduction before a wider audience of synastry-focused astrologers took it up more widely from the 1970s onward; because it depends on geographic latitude as well as time, the Vertex changes noticeably for people born at the same moment in different places, a sensitivity to location even sharper than that of the ordinary angles.

The Vertex is where the prime vertical, the great circle running through the east and west points of the horizon and the zenith, cuts the ecliptic in the west. There is a compact way to compute it that also explains its behaviour: the Vertex is the ascendant calculated for the co-latitude, that is, for 90 degrees minus the geographic latitude of the birthplace, taken in the opposite hemisphere.

That identity has consequences. A chart cast at 50 degrees north has a Vertex behaving like an ascendant at 40 degrees, and one cast at 20 degrees north has a Vertex behaving like an ascendant at 70 degrees, with all the extreme unevenness of rate that a high latitude ascendant carries. Towards the equator the co-latitude approaches 90 degrees and the computation degenerates, so the Vertex becomes unstable and then meaningless for births within the tropics. Software that reports one anyway is reporting an artefact.

Its rate is otherwise a full circuit in a sidereal day, so it is as time-sensitive as the ascendant and rather more location-sensitive, which is the point the existing article makes about people born at the same moment in different places.

Two names collide here and the atlas holds both. This Vertex is a calculated point of the twentieth century. Vertex is also the traditional name of a fixed star position associated with the Andromeda Galaxy, which has nothing to do with it.

The Vertex is one of a number of calculated points introduced into twentieth-century Western astrology to supplement the classical angles. It is a geometric construction rather than a visible body, and unlike the lunar nodes or the Part of Fortune it carries no pre-modern documentary history at all, since its underlying geometry, the prime vertical, only became a routine tool of chart calculation once spherical astronomy was applied systematically to natal charts in the Johndro-Jayne research of the 1930s through 1950s.

Partly for this reason the Vertex never acquired a single glyph with anything like the universal recognition of the older planetary and asteroid symbols; software and printed ephemerides commonly abbreviate it simply as Vx, with AVx for the Antivertex, rather than drawing a dedicated pictorial mark, a plain notational habit that reflects the point's comparatively narrow and recent adoption even within contemporary astrological practice. Where the four asteroids and the lunar nodes each carry glyphs that trace back through nineteenth-century astronomy or medieval and ancient manuscript traditions respectively, the Vertex illustrates the opposite case, a chart factor whose entire documented history sits within living astrological memory, described in the technical vocabulary of early twentieth-century American astrology rather than inherited from any older source.