In most types of astrology the Midheaven (MC, or Medium Coeli) is considered to be of extreme importance. Most quadrant house systems use the MC as the cusp of the 10th house. Some astrologers incorrectly refer to the MC as the ‘zenith’ or as the ‘highest point in the chart’. In fact, at the moment for which the chart is cast the MC is rarely the highest point above the horizon in the chart. A bit of reflection will help us to understand why this is so.
The two principal axes in the horoscope wheel are the horizon and the meridian. These circles divide the astrological chart into four quadrants, which are further subdivided into three astrological houses in the quadrant house system. The horizon is the imaginary circle surrounding the observer at which the earth’s surface and the sky appear to meet. The meridian is the imaginary circle of constant longitude passing through the observer’s location on the earth’s surface and the terrestrial North and South poles. Western horoscopic astrology is based on the overarching importance of the eastern horizon, the so-called ‘horoskopos’ or marker of the moment of birth. The MC or Midheaven is the point where the meridian circle of the observer’s location intersects the ecliptic circle (the path of the Sun in the geocentric model) above the observer’s horizon.
Distinct from the MC (Midheaven) is a point called the ‘Nonagesimal‘, which is in fact the highest point of the ecliptic above the horizon at the moment for which the chart is drawn.
The site lexico.com notes that the word ‘nonagesimal’ derives from the classical Latin nōnāgēsimus ninetieth (from nōnāgintā ninety (from novem nine + -gintā, suffix forming cardinal numerals from thirty to ninety, related to decem ten: see decem-) + -ēsimus, extended form (after vīcēsimus) of -simus, suffix used to form ordinal numerals) + -al, and defines ‘nonagesimal’ as:
“The point of the ecliptic which is highest above the horizon at any given time, being 90 degrees round the ecliptic from the point at which it intersects the horizon.”
In other words, the Nonagesimal is the point on the ecliptic above the horizon that is exactly 90 degrees from the Ascendant degree, that is, it is the midpoint above the horizon of the Ascendant and Descendant degrees of the chart. In the equal house system from the Ascendant, the Nonagesimal is the cusp of the 10th house. In Hellenistic astrology a planet on the Nonagesimal forms a dominant square with respect to the Ascendant and has a powerful effect on the vitality, motivations and life course of the native. Applying this Hellenistic principle to horary astrology, a planet on the Nonagesimal (the highest point above the horizon) would have a major and overarching impact on the Ascendant, which signifies the querent as well as the horary question itself.
Why is the elevation of a planet so important? My hunch is that the idea of the importance of elevation dates back to the Persian influence on Hellenistic astrology. When Alexander the Great conquered Persia in 334 BCE, he became enthralled with the idea that no one’s head should be held higher than that of the king. The following passage from the book Shanameh: The Persian Book of Kings illustrates this idea (italics mine):
“When Zal saw Kavus sitting in state on the throne, he bent his arms submissively across his chest and lowered his head. He said, ‘Lord of the world, whose head is lifted higher than those of all other noblemen and chieftains, no one has seen a king like you occupying the throne …”
Alexander brought back not only astrology but also parts of Persian culture (including the significance of elevation above others as an indication of status and power) when he founded the city of Alexandria, which became a center for the development of Hellenistic astrology.
Recently I was looking at a horary chart in which Mars was almost exactly conjunct the MC, thus making Mars a highly significant planet in interpreting the chart because of its prominence on the Midheaven. About 11 degrees to the west of Mars was Mercury, cadent in the 9th house. Cadent planets are supposedly less influential, but in this case Mercury was more elevated than Mars and would play a major role in the interpretation of the horary figure. Specifically, Mars had an altitude above the horizon of 30n34, and Mercury had an altitude above the horizon of 35n25′, almost 5 degrees higher than Mars. The following figure from Stellarium illustrates this fact.
The practical implication of the Nonagesimal as the highest point in the chart is that we should pay close attention to planets conjunct the Nonagesimal, much as with do with planets conjunct the Midheaven. For advocates of Ebertin’s midpoint system, the Nonagesimal is the Asc/Dsc midpoint above the horizon and, as such, is symbolically extremely significant, especially when conjoined by a natal, directed or transiting planet.
Addendum (15 July 2021): Comments from Facebook
I am grateful to the several gifted astrologers who responded to this post on Facebook and added comments which further clarify and amplify this topic. The most detailed of those comments are copied and pasted below:
Nāthan Theodore Naicker Thanks Anthony. It is an important point. Just adding some info for thought: I’ve noticed in many cases that any planet in the same degree as the AC (irrespective of sign) has a profound impact on the AC, as external factors impacting/influencing the AC and especially mental health. In that context, the AC degree in the tenth sign of the chart (nonagesimal) would be able to exert a dominating influence on the AC. As an aside, in traditional Vedic astrology, planets in the tenth can have the same influence – that is, an overriding influence on the AC, unless the AC is stronger. In that system, the tenth house is the strongest angular place (all other factors being equal). Of course for one to be sure in applying this, a verified birth time is needed, but one can practically apply it with a small orb.
Paul Kiernan This is really important stuff Anthony Louis. One thing I’ve seen a lot of is the notion that Equal Houses, being simple to calculate, lacks astronomical merit. I’ve been banging on about this for years to anyone who would listen but Equal Houses astronomically models something which no other house system does. I personally liken the difference in MC and nonagesimal as being one where the nonagesimal wins the race but MC reaches its personal best. Noteworthy here is that both of these ideas are discernible within the signification of the 10th. Equal House users have always managed to benefit from both important astronomical points by adding nuance to the MC falling in a different sign, but I feel Quadrant and Whole Sign users could do likewise by including the nonagesimal (technically WSH users would need to consider both points, neither of which are directly implicit in its construction except that the nonagesimal falls, somewhere, in the 10th).
Derek Norcott THE ASTRONOMY:In short: Upper nonagesimal and Lower nonagesimal are high and low points of the visible-invisible right (snapshot) ECLIPTIC sphere; RAMC and RAIC are high and low points of the ascending-descending (rotational) right EQUATORIAL sphere. When substituting ecliptic juncture with the meridian, the RAMC–RAIC representation becomes the MC and IC.
THE ASTROLOGY: When using the movement of the planets through the houses along the ecliptic, the right-hand side of the horoscope (IC to MC) becomes the ascending side and the left-hand side (MC to IC) the descending side. (This is despite the apparent movement of the celestial sphere moving clockwise, as the anti-clockwise movements of celestial bodies along the ecliptic visible sphere is what astrologers are most interested in with regards to transits and progressions, etc.)In polar regions, the MC can be below the horizon and the IC above the horizon, though still representing extremes of altitude of the ecliptic degrees during that daily movement.
INTERPRETATION:This means that the MC is NOT the most public visible place, but instead the highest potential for achievement: the future; likewise, the IC is NOT the most private invisible place, but instead the historical origin of the person: the past. These concepts are continuously in our minds as future intent and a harking back to our past. The most public is the Upper nonagesimal; the most private is the Lower nonagesimal; and is our need to be most visible to strangers and extravert, or most hidden away in our exclusive groups, on our own and introvert.I hope this elucidates the difference in the meaning of these points.——
Further info: Planets moving over the Descendant is where one moves into the public visible hemisphere and concerns oneself with other people and their needs. Whereas, planets moving over the Ascendant is where one moves into the private invisible hemisphere and concerns oneself with one’s own responsibilities and needs. This is speculative: Planets moving over the Equatorial Descendant is perhaps where one sees potential for future growth with others; whereas, planets moving over the Equatorial Ascendant is where one perhaps starts to reflect on past events and how one could have done things better. As for Anti-Vertex and Vertex: I can’t see what role these can play as they don’t participate in the movement of planets either along the ecliptic or the equatorial. It is said that the Vertex represents people coming into pone’s life and the Anti-Vertex, people going out of one’s life. However, this is more in tune with the logic of the Equatorial Descendant and Equatorial Ascendant, respectively.(BTW: Just as the MC and IC reflect the Equatorial’s RAMC-RAIC, but along the Ecliptic plane instead; so the Equatorial Ascendant and Equatorial Descendant reflect the Equatorial’s East Point and West Point, but along the Ecliptic plane instead. Using the Equal House system creates equal division of the Ecliptic (visiblity sphere); the Meridian/Axial House system creates an ecliptic representation of equal divisions along the Equatorial (rotational) sphere. Using both together has some logic behind it.