Rhys Chatham explains how the major house division systems are calculated in a way that does not require any math.
Rather than advocate the use of one house system over another, we will simply compare them and look at the various celestial circles they are based on, reflecting upon the symbolic implications of each of them and how they might impact on chart interpretation. We’ll discuss what distinguishes one house system from another, allowing you to make informed choices on which ones to use, for what, and when.
In this talk we will cover the ecliptic-based (whole sign, equal and Porphyry), space-based (Meridian, Regiomontanus, Campanus), and time-based houses (Alcabitius, Koch and Placidus).
It’s free! If you would like to attend, click on the site (below) to register and get your ticket and Zoom codes.
House division systems are based on different celestial circles. After a quick review of the astronomy, we’ll discuss those differences and look at how they might affect chart delineation on both symbolic and practical levels.
Lilly says that while there are many demands which may be made concerning questions to the 3rd House, the principle ones concern:
The querent’s brethren, brothers/sisters/close relatives that aren’t parents. Is the relationship between the querent and them harmonious or not?
What of a brother or sister who is absent? Are they alive or dead? Are they prosperous or not? Are they happy? When is the querent likely to have news of them? Are they likely to come back home, and if so, when?
Another question covered is whether the querent will have brothers and sisters. And if so, will he get along with them?
How to judge these questions:
If the question concerns brethren, look at L1 for the querent and L3 for the quesited. Look at the condition of both of the lords and see what condition they are in. See if there is an aspect between them and if there is, is it good or bad? In this way, one can answer the above questions.
Also look at the concerned houses, e.g. if a malefic or the south node is places in the 1st House, it shows there are problems with the querent. If they are in the third house, then the kindred is the problem.
To learn more about the condition of the kindred, turn the houses so that the third house represents the kindred and becomes the Ascendant or 1st house. So the radical 5th House becomes the turned or derived 2nd house, etc.
On another topic, on CA page 192-194 we cover the topic of whether a rumor be true or false.
While rumors are attributed to the third house and its Lord or Lady, Lilly has us consider the angles, the Moon and Mercury among other things; the rules are a bit complicated and often involves bringing other houses into the picture.
Reports, News, Intelligence or Fears? Are they true or false? Do they signify good or evil? (CA pg 192)
Lilly found that during a time of war that the rumor was true IF the Moon in either H1, H3, H10, or H11 separates by a benevolent aspect from any planet, and then applying by sextile, trine or conjunction to the Lord of the Ascendant.
However, if the Moon applied to L7 by any good aspect, enemies would have the victory.
If the Moon was void of course, the rumor would come to nothing or be a lie or false.
If both Moon and Mercury were square or in opposition to each other, and neither of them cast a sextile or trine to L1, the news was false.
Also, from CA page 193:
If at any time you hear some news and want to know if it is prejudicial to you… It will not be detrimental to you if:
Jupiter or Venus is in the Ascendant
Or if the Moon or Mercury be in their essential dignities and in trine or sextile to L11
It will be detrimental to you (or to whom the news concerns) if:
L6, L8, or L12 is in the first house or in bad aspect to L1.
Or if Mars or Saturn is retrograde in H1, or in hard aspect with L1, or casting a square or opposition to the Ascendant degree.
If Saturn signifies the mischief: country friends have been plundered, cattle stolen
If Mars, someone has been cut off (“straggling parties”)
Mercury: letters have miscarried.
Jupiter or Venus (involved gentlefolk)
Lilly says to use common sense.
If counsel or advice given is good or evil? CA pg 194
If the rumors be true or false according to the ancients:
The rumors are true if:
Consider L1 and the Moon, if they are in an angle,
or if the dispositor of the Moon is in an angle and in a fixed sign,
or if any of these be in a succedent house and fixed sign,
or in good aspect with a fortunate planet i.e. sextile or trine with Jupiter, Venus or the Sun
Judge to the contrary if:
L1 is afflicted by Infortunes
Or in a cadent house even if strong in sign (essentially strong.)
Pg 194 – Rumors are for the most part true when:
Angles in figure are in fixed signs, separating from Infortunes and applying to any fortunate planet, placed in any angle. Moon and mercury in fixed signs separating from Infortunes and in an angle.
If the Angles of H4 & H10 be fixed and the Moon received in them (i.e. the Moon is in one of those houses?)
Rumors of evil will be false or turn into good things if:
If one hears evil or bad news yet one of the fortunes is in H1 or the Moon be unfortunate, it is a strong argument that the rumor is false, and they will turn to good rather than evil.
If Mercury is retrograde or in any other way afflicted, or of that planet to whom the Moon applies (that it be retrograde?), or to whom Mercury applies, esp. if either of those two are lords of the Ascendant.
If L1 is under the beams of the Sun the matter shall be kept secret and few will ever know the truth of it.
Of counsel given, whether it be for good or evil.
Counsel is given with an honest heart if:
Fortunate planet at MC or in H10 i.e. Sun, Jupiter, Venus or North node, otherwise Moon applying to L1
Counsel is given with malintent if:
Saturn, Mars or south node in in H10.
Also, if the Ascendant is moveable (cardinal), the person giving the counsel is deceitful or treacherous.
By this Lilly means journey that only takes a day or so.
An afflicted 3rd House in relationship questions suggests communication problems or mental incompatibility. In business questions it indicates contractual problems. Mars in H3 and indicate arguments, Saturn an inability to communicate.
This article on ecliptic-based house division is Part 3 of a three part series. To start at the beginning , click here.
Porphyry is a quadrant house system. In quadrant house systems, the ascendant defines the first house cusp, and the MC defines the tenth house cusp. This creates four sectors or zones within the circle of the ecliptic, otherwise known as quadrants.
Named after the third century Neo-Platonist philosopher and astrologer, Porphyry, this system was used from the earliest days of horoscopic astrology and was described by Vettius Valens in Book 1 of Anthology, his astrological textbook.
In the Porphyry system, the span of the ecliptic between the horizon and midheaven is trisected to produce three houses. This makes the houses very easy to calculate, you can practically do it in your head! Because the number of degrees between the ascendant and MC vary according to location, time of day and season, the quadrants are rarely of equal size.
The advantage of Porphyry houses is that the first house cusp starts at the degree of the Ascendant, and the degree of the MC defines the 10th house cusp, thus underlining the importance of angularity in horoscopic astrology. In doing this, Porphyry anchors houses to the earth in that it is the local horizon that defines the start of the first house, and the local meridian that defines the 10th house cusp and MC.
One reason astrologers use quadrant house systems is for the same reason that they use the tropical zodiac: because they are tied to what’s going on in the sublunar world. Just as the tropical zodiac is tied to the earth’s seasons, quadrant houses are tied in profound ways to the physical earth itself. The idea behind using quadrant houses is that they better reflect what is happening in the terrestrial world as opposed to the sidereal world.
Furthermore, with Porphyry, we distinguish and underline the difference between a planet being domiciled in a sign and a planet being in an astrological house.
An astrological house represents things that are linked to the Earth that we live on, the domiciles are in the heavens. For example, we could have two planets domiciled in Aquarius, with Mercury in Aquarius in the 12th House and Saturn in Aquarius in the 1st House (see chart below).
We lose this symbolism in Whole Sign houses (see chart above), but we get it back in quadrant systems and in systems where the 1st House starts with the Ascendant, which is one reason why ancient astrologers used quadrant house systems in addition to WSH cusps.
Granted that the Porphyry system is more anchored to the earth and that it is a quadrant system, it is still based primarily on the ecliptic. So, after a time, astrologers began entertaining the idea of basing the houses on celestial circles other than the ecliptic, perhaps ones that were more linked to the earth, such as the celestial equator and/or the prime vertical. This would bring us to a discussion of the space-based houses, which we will save for a future blog. For now, let’s move on to our conclusions of what we’ve covered so far…
We’ve been discussing the ecliptic-based house systems: Whole Sign Houses (WSH), Equal and Quadrant Houses. Which house system should we use?
Which one to use depends on what system of astrological praxis one is following. If you’re following Project Hindsight (Robert Schmidt, Robert Hand) and its followers, you’ll probably want to use mainly WSH, using equal and perhaps quadrant houses for planetary strength and length-of-life. However, later scholars who reviewed the same material as Project Hindsight have recently arrived at alternative interpretations regarding Hellenistic house doctrine. Some seem to think that degree-based quadrant houses were used by the ancients for topics, in addition to planet-strength and length of life. These scholars conclude that the ancients (Dorotheus, Ptolemy, Valens, et. al) used quadrant houses for more precise readings, when the exact birth time was available. Exact birth times often were not easily come by in ancient Greece, in which case WSH were used.
This undoubtedly was most often the case (no exact birth-time) resulting in a highly developed Hellenistic technique of using sign-based aspects and houses for delineating a chart. Also, it made casting a chart less time consuming (no computers in ancient times), so it makes sense that degree-based houses and aspects were used only when a birth time was available and when a high degree of accuracy was called for.
However the ancient Greek astrologers may have calculated their house cusps, my policy with respect to these new scholastic findings is to keep an open mind and not fall into the trap of turning previous interpretations of the ancient Greek authors into dogma. On a practical level, my personal choice is to use both WSH and quadrant houses for topics in the context of natal readings.
Modern astrologers, of course, feel free to pick and choose whatever techniques work for them. If you fall into this category, I would highly recommend basing your choice on the celestial circles that we have been discussing. Keep in mind their symbolism, and use whichever house system corresponds best to the goals of your astrological tradition (ancient, classical, humanistic, psychological, evolutionary, etc.)
As we have seen, each house system is based on a different set of celestial circles, which render varying house cusps and sometimes put planets in different houses. Let’s say that this happens when using whole sign houses and Porphyry on the same natal chart (see example above).
Saturn jumped from the 12th House to the 1st House, oh dear! What do we do?!?! Which chart do we use? Which one is “right”?
The answer to this question is that both charts are right; the only thing that is happening is that we are seeing the same native from different perspectives! It is not a question of choosing between one or the other. Both must be interpreted.
So, when looking at a natal chart, I have found it is always best to try putting it in more than one house system to see if any of the planets change houses. When they do, I look at the changes with interest and delineate both.
Working simultaneously with two house systems often yields interesting information. For example, if I’m using WSH and Porphyry or some other quadrant system, when I see a planet move from one house to another, I interpret both and see what resonates with the client. With clients who are past their second Saturn return, I have found that both usually resonate, representing different aspects or periods of their lives. For younger clients this is not always the case, because it may be that the symbolism represented in one of the charts has simply not happened yet.
Another thing to keep in mind is which house system we use depends on what we are attempting to do.
For example, if we are focused on prediction, we might use one house system, in horary we might favor another, in natal analysis another. Ideally, the house systems we use would be based on which celestial circles are used to determine the house cusps, and how the symbolism of those circles relates to what we’re trying to accomplish. For example, what is prediction? It is a form of fate. Where does fate come from? One way of putting it is that it is in the hands of the universe. It might make sense to use whole signs in that case, since the house cusps in whole signs are based in the heavens, rather than where we live on the planet Earth. On the other hand, if we are looking for a lost object, we might want to use a space-based system like Regiomontanus. We’ll talk about space-based systems in another article.
Moving on, in conclusion, I’d like to say that all the symbolism I’ve mentioned up to now are just ideas to get the conversation going amoung present day astrologers: traditional and modern. Rather than arguing in favor of one house system over another, it might make more sense to focus our research on which house system is best for which astrological technique based on the celestial circles that come into play.
The article is Part 2 of a three-part series on ecliptic-based astrological house division. If you haven’t read Part 1, click here.
Part 2: Ecliptic-based House Division:
The Equal-House system is a variation of the whole sign house system. The difference is that the degree of the ascendant defines the start of the first house and becomes the starting degree of each of the remaining eleven houses. The MC floats and does not define the cusp of the tenth house.
Since Hellenistic times and before, astrologers have been concerned with the motion of the planets rising over the horizon, culminating at the MC, and finally disappearing into the darkness at the descendant. This is called primary motion, it is concerned with the rotation of the earth on its axis and with the motion of the stars, luminaries, and planets above us as they move during the course of the day.
The Acendant is the point where the ecliptic meets the local horizon. With the equal house system, we start to anchor the houses to the rotation of the earth by linking the ecliptic with the local horizon of the native or event. As we have noted in a previous post, the ecliptic is extra lunar, it is not of this earth. However, the local horizon is sublunar. So, with equal houses, ancient astrologers found an initial way to ground the ecliptic to events on earth.
The personal point of the degree of the Ascendant is emphasized in this system. The symbolism becomes a bit more grounded in that the eastern horizon takes on an elevated importance.
In the entire range of traditional natal astrology, the first house represents YOU, it represents the native. The rest of the houses represent everybody and everything else! Echoing the degree of the Ascendant in each of the subsequent houses underlines that this house system symbolizes YOUR money (2nd house), YOUR siblings (3rd house), YOUR home (4th house), and so on.
To compare equal houses with whole sign, in WSH there is no difference between a planet being domiciled in a sign and a planet being in a house. In whole sign houses, we don’t really have houses, what we have are signs. Can signs alone be used to define house cusps? Of course they can! The WSH system was probably used extensively in Hellenistic times and is one of the major approaches in Vedic astrology. However, when we use this method we lose the connection of astrological houses moving clockwise by primary or diurnal motion. In WSH, secondary motion along the ecliptic is emphasized, that is, planets and other objects in space moving in a counterclockwise direction along the ecliptic.
In WSH, signs are houses. A planet domiciled in a sign in WSH exactly corresponds to it being in an astrological house, so we lose the symbolism that we get when we separate domiciliation (Jupiter and Neptune in Pisces) from the symbolism of houses (Jupiter in Pisces in the 1st House, Neptune in Pisces in the 2nd House).
In Equal Houses, we start to get this symbolism back (see chart above). We put the signs back in the heavens, as the first manifestation of the Primum Mobile, and we begin to ground the houses back to the geocentric earth, where, after all, we live!
By defining the Ascendant as the start of the first house, we regain the demarcation between a planet being domiciled in a sign (Jupiter and Neptune in Pisces) and planets being in an astrological house (Jupiter in Pisces in the 1st House, Neptune in Pisces in the 2nd House).
However, the work of the ancient astrologer was by no means finished! The equal house system was still a non-quadrant house system in that the MC is floating. To further ground the houses to the sub-lunar realm of the earth, the ancients developed other house systems, which anchored the local meridian or latitude of the native to the cusp of the culminating tenth house.
In my next post, we’ll look at the quadrant house system that is most often referenced by scholars to the Hellenistic period. Today, it is known as the Porphyry house system.
Before moving on to the astronomy of the ecliptic-based house systems, I had another thought on the current WSH war.
Those of us interested in Hellenistic Astrology owe a great debt to the research done by Project Hindsight (PH) and the folks who did the research, primarily Robert Hand and Robert Schmidt, and at the start Robert Zoller. Also we can give our gratitude to Chris Brennan, whose book Hellenistic Astrology (HA) attempted (and largely succeeded) to put the entire doctrine of HA as understood by Project Hindsight and himself into one volume. This was followed by two volumes by Demetra George on the praxis of Hellenistic delineation, with Volume 1 looking at planetary strength and other technical subjects from a mostly Hellenistic perspective, and Volume 2 to looking at house delineation in a way that included the entire astrological tradition, from Hellenistic to 20th century astrology.
Thanks to these efforts, HA and some of its techniques have become widely popular, so quite naturally other scholars and academics are joining in and looking at the relevant texts in their original languages (Greek, Sanskrit and Latin). Further interpretations and alternative views of the Hellenistic tradition are beginning to appear as time passes. One hopes that the PH point of view will not become dogma and that folks will listen to other viewpoints with an open mind.
Deborah Houlding has an alternative interpretation of Anthologies by Vettius Valens.
I believe that folks have misinterpreted her recent talk at the Astrological Association of Great Britain in thinking that she was saying whole sign houses (WSH) never existed. What she meant to get across was that no ancient or medieval author ever formally defined or endorsed their use, which is not the same thing as saying WSH never existed. One can either agree or disagree with her point of view. Also, she didn’t mean to leave the impression that prior to the 80s, no one wrote about or mentioned WSH, ever. She simply meant that prior to PH, WSH were not a “thing”. It wasn’t generally talked about in the astrological community, indeed, even people like her doing traditional astrology (as medieval and renaissance astrology was called back then) were considered slightly mad. Hellenistic astrology was strictly for the academics.
Unfortunately, her presentation contained inaccuracies, snide comments about colleagues and bordered on presenting PH as a kind of evil cabal. This was not helpful to her cause, which was to present an alternative view on how ancient astrologers worked with houses. Completely lost in the subsequent furor was her fascinating discussion of primary vs secondary motion as it related to WS and quadrant houses. The lesson to be learned from this is when presenting an alternative view on a hot-button topic, it is best to stay away from personalities and stick to principles; to stay on topic and avoid dragging out the dirty laundry along the way.
Chris Brennan responded to Houlding with a video stream where he played her entire talk and calmly responded to it, point by point. He also did interviews with Robert Hand, one of the founders of PH, as well as with Demetra George, an early PH participant and proponent, each of whom gave their reactions to the Houlding talk. For anyone who is interested in Hellenistic astrology, these videos make for fascinating watching. Responding to the Houlding talk almost becomes secondary; one gets a sense of what PH was and how it developed; the interviews are in no way a shouting match.
I saw a YouTube video recently depicting Chris Brennan as some kind of power hungry, evil empire Darth Vader type for responding to the Houlding talk. Nothing could be further from the truth. Brennan is by no means a HA fundamentalist, just look at his podcast: He has medieval and renaissance astrologers on the show, he has psychological astrologers, he has evolutionary astrologers, vedic astrologers, he even has had “pop” astrologers present their work. Brennan promotes astrology in all its forms. Outside the context of his book and HA course, his astrology is a blend of Hellenistic and modern practices, as is D. George’s. I believe that Houlding in her talk was simply speaking from her heart and calling things as she saw them. However, because the talk unfortunately contained a good deal of hyperbole and what Brennan considered falsehoods, he felt obliged to respond. I don’t see how we can fault him for that.
With all that being said, the understanding of Hellenistic house division practice is evolving and we are beginning to hear new viewpoints. We’ve heard the one by Deborah Houlding. Here is a new viewpoint from Martin Gansten, a traditional astrologer who is also an academic. He reads Greek, Latin and Sanskrit and is thus able to do his research using critical editions. He recently responded to those who call him a whole sign denialist in a short piece written by an astrologer for other astrologers (rather than for academics) . He did so in a way that simply laid out his points in a line, for all to consider, to either accept or reject. It is a model of how a debate on a controversial subject ought to be conducted. Here is a link to the piece:
As I mentioned in a previous post, I’d like to gently shift things away from the WSH controversy, and instead of focusing on which ancient astrologer used which house system, and for what, I plan to look at the astronomy and symbolism of the ecliptic based houses: WSH, Equal Houses, and what today we call Porphyry Houses, which is an exquisite quadrant system that was used in Hellenistic times.
Each of these systems emphasizes particular celestial circles. WSH emphasize the ecliptic itself. Equal Houses bring the great circle of the horizon strongly into the mix. The Porphyry system of house division adds the local meridian of the native or event.
In my next series of posts, I’ll discuss the interesting features of each of these three systems, without promoting one over the other. We’ll look at the celestial circles that come into play in determining the house cusps, and together we will discuss their possible symbolic implications.
This is a short video which considers what traditional astrology has come to mean today, as opposed to what it signified in the recent past. The differences between traditional and ancient astrology are broadly discussed.
If video takes too long to appear, click here for direct link.
I’ve been thinking about the astrological Ages of Man/Woman persons.
These are divisions of time using the Chaldean order of planets to describe a psychological progression in the stages of human life, which we find described in the Hellenistic astrologer Ptolemy’s work, Tetrabiblos.
Briefly the seven “stars” or visible planets and luminaries each describe a stage of life and its experience, with a certain number of years aligned to each (see illustration above).
The quality of the period depends on the condition of the ruling planet in the nativity of the person in question, which we would determine through using either Hellenistic or medieval/renaissance traditional techniques (or both…)
I tried this on my own chart by simply using essential dignities to determine planetary condition. I’m in the crone stage of my life (i.e. I am pushing seventy…) so I’ve reached the Saturn Age already. In looking back over my life, I found the planetary ages corresponded quite nicely with what I experienced
My partner is roughly the same age as me, and their periods also corresponded accurately. I’m going to include this technique as a quick way of getting a sense of a native’s life in working with nativites.
I’ll let you know if my Saturn period works out as I expect when I am 98 years old!
In the first time-based house system that we looked at, the Alcabitius system, we carefully measured the time it took for the point of the ascendant (the point where the horizon meets the Sun’s path along the meridian), to reach the culmination point of the Sun at the midheaven, or MC (Medium Coeli).
We then took the total time of the Sun’s path along the ecliptic from the ascendant to the MC and divide the time it took into three equal parts. Adding one of these parts to the time of the ascendant gives us the time when the point of the ascendant reaches the 12th house cusp, adding the sum again gives us the 11th house cusp, and we convert those times into degree points on the ecliptic.
The beauty of this system is that it is linked to the local meridian, and thus more directly to the location of the earth-based native of the chart.
With Alcabitius, at first glance it would appear that since time is trisected between the ascendant and the MC, that the time it takes for the Sun (or any planet) to travel would be the same for each of the trisected houses, since each of the houses represent an equal amount of time.
However, this is not the case. And this is where the innovation of the Placidus system enters the picture.
The fact of the matter is that the Sun transverses some astrological signs more quickly than others. This is what William Lilly referred to as “straight signs” versus “crooked signs”. Or put another way, “signs of right ascension” as opposed to “signs of oblique ascension”, or “signs of long ascension” vs “signs of short ascension”.
Because of the way the earth is tilted with respect to the ecliptic, six of the constellations along the ecliptic seem flatter/not as tall/crooked/shorter than the other six, which appear to be standing upright, “straight”, or long.
The Sun takes less time with the crooked/oblique/short signs to “ascend” along the ecliptic than it does with the upright, straight, or long ones.
In the northern hemisphere, the signs of right ascension (straight/upright/long) are: Cancer, Leo, Virgo, Libra, Scorpio and Sagittarius.
The signs of oblique ascension (crooked/oblique/short) are: Capricorn, Aquarius, Pisces, Aries, Taurus, Gemini.
In the southern hemisphere, due to the earth’s tilt of 23.5° in relation to the ecliptic, these are reversed: i.e. the signs of long ascension become the signs of short ascension.
You can easily see for yourself how widely the ascension times vary for each sign in any astrological program capable of animating a chart wheel, such as Astro Gold or Solar Fire. I’ve prepared a demonstration video in Solar Fire to demonstrate this, you can do it yourself at home!
And here is a lovely YouTube video using Stellarium and Sumer 1.3 by Rumen Kolev which demonstrates the phenomenon of long ascension versus short ascension quite nicely, observe especially the image on the right:
So in summary, Porphyry is an ecliptic-based system which simply divides the ecliptic in three equal parts from the ascendant to the MC, and then again from the MC to the Descendant, and by extension to the rest of the 12 astrological houses.
Alcabitius is a time-based system, which measures the time it takes for the point of the ecliptic to move in a diurnal (primary, literally “to the right”) direction until it reaches the MC. We then divide the time by three (rather than dividing the ecliptic itself). Then we do this operation again from the IC to the ascendant, and by extension the rest of the twelve astrological houses.
Placidus was an innovation, in that it took into account that although the signs are a standardized 30° each on the ecliptic, the Sun moves along these signs at different rates of speed due to their positioning in relation to the local meridian. It is thus a more accurate representation of the size of an astrological house in relation to the native’s position on earth. We do not get this in any of the other previously mentioned house systems.
We will go more deeply into the Placidus system in the next post.
Earlier, we spoke of ecliptic-based house systems (c.f. blog 24 January 2021).
In the course of talking about these older house systems, we are going to look at the ecliptic, the horizon and the meridian, see what they look like in the sky above us, and finally we will look at how they are represented in an astrological chart.
The easiest house systems to calculate are the ones that are based on the ecliptic. The three major house systems based primarily on the ecliptic are: (1) the whole sign house system (WSH), (2) the equal house system, and the (3) Porphyry house system.
These three house systems use as their basis three great celestial circles: the ecliptic, the local horizon, and the local meridian and are easy to calculate. All one needs to know is the longitudinal position on the ecliptic of where the ecliptic meets the horizon, this is called the ascendant.
Then we need to find the point where the ecliptic meets the local meridian, this is called the midheaven.
Once we know these positions, the rest of the calculations can be done in one’s head!
I’d like to introduce a more complex house system, but before we get to that, let’s review the basic celestial circles that we have covered so far: the ecliptic, the horizon and the meridian.
The ecliptic, of course, is the apparent path of the Sun as it is seen from the point of view by an observer on earth.
The five visible planets never drift too far from the path of the ecliptic, so in astrology we usually measure the longitudinal position of the luminaries and planets, including the outer ones, as longitudinal degrees along the 360° circle of the ecliptic, which by convention we divide into twelve sectors of 30° of longitudinal position each. Each of these twelve sectors is represented by an astrological constellation (Aries, Taurus, Gemini, etc.), which may or may not correspond with the ones in the sky.
The horizon is the great circle on the celestial sphere that is directly between the zenith (the point directly above you) and the nadir (the point directly below you).
The horizon is always perpendicular to the local zenith and nadir, that is to say the horizon is 90° from the ascendant.
The meridian is the great circle passing through the celestial poles, as well as the zenith and nadir of an observer’s location. In astrology, the midheaven is defined as the point where the ecliptic meets the local meridian.
How the great circles are represented in an astrological chart:
In an astrological chart, we squish these great celestial circles together, we flatten them so that they are represented by straight lines:
The outer circle represents the ecliptic, and on it we see the degrees of the house cusps, which were calculated in Porphyry in this chart.
The vertical line going from left to right, from 5° Leo to 5° Aquarius, represents the horizon, which of course is actually a circle, not a straight line. Because western astrology was developed in the northern hemisphere, the Sun was always to the south. So since the chart assumes that we are facing south, the east is on the left and the west is on the right. This convention has stayed with us through the ages, and we use it today, even if we live in the southern hemisphere.
Finally, the vertical line that goes from the bottom at 15° Libra to the top at A5° Aries represents the local meridian, which of course is also a great circle, and not a straight line (c.f. illustration 3). The point of the midheaven represents the point where the two circles intersect: it is the point of intersection of the meridian with the ecliptic.
The beginning of the tenth house in a quadrant house system such as Porphyry, Alcabitius, Campanus, Regiomontanus or Placidus is called the Medium Coeli (M.C.), which is Latin for midheaven.
The M.C. is where the Sun reaches its highest point in the local sky, NOT to be confused with the zenith, which is the point directly above the observer.
So, to give an example, if one is in the northern hemisphere at a mid-latitude location, for example Wisconsin, or in Europe in France, the Sun would be towards the south as it rises, culminates, and sets. The Sun only passes directly overhead the observer at the equator. The Sun travels along the ecliptic, the local meridian is perpendicular to our local horizon, so basic physics tells us that the Sun will reach its highest point when, travelling along its path on the ecliptic, it meets our local meridian.
Our local zenith is also on our local meridian, it is directly above where one is standing. But the local zenith is not on the path of the ecliptic, unless we happen to be standing exactly on the equator!
Having reviewed these three basic circles, in the next blog I hope to cover later astrological house systems. The next one we will cover is the Placidus house system.