In Search of the Best House System
published in ISAR International Astrologer, Leo 2007, p. 79-83
Meet little Andrey, a real, live new-millenium boy. He was born on January 1st, 2000, at 00:00:30 am in Murmansk, Russia, 68° 34' N, 33° 8' E.
If you use the Placidus House System, you cannot construct a natal horoscope for Andrey. Nor will you be able to construct a chart for a wedding or important event for Andrey in Murmansk. Nor can you construct a natal horoscope for any of the 320,900 people born in Murmansk- nor in Nordvik, Republic of Sakha (population 55,000), Holsteinsborg, Greenland (population 5,222), or Point Hope, Alaska (population 760). The Placidus House System is undefined for latitudes above 66°33', the Arctic Circles.
Why? The Placidus House System takes the Midheaven and Ascendant, which are astronomically defined, as the cusps of the 10th and 1st houses, respectively. The arc between these points represents a half-daytime and is called the semi-diurnal arc. Then the time of the semi-diurnal arc, from birth until the Ascendant degree culminates, or reaches the Midheaven, is found. Adding one-third of this time to the sidereal time of birth gives the cusp of the 12th house, and adding two-thirds of this time gives the cusp of the 11th house. Similarly, the time of the semi-nocturnal arc, the half-night from Nadir to Ascendant, is trisected and subtracted from the time of birth to give the cusps of the 2nd and 3rd houses.
The semi-diurnal and semi-nocturnal arcs are not the same everywhere on the Earth, but vary according to latitude. This dependence on latitude allows the Placidus House System to distinguish between people born at exactly the same clock time but at different locations.
However, at polar latitudes some degrees of the Ecliptic never touch the Horizon. Therefore, there is no semi-diurnal or semi-nocturnal arc to trisect, and a chart cannot be constructed at all using the Placidus System. For example, in Murmansk on Andrey's birthday, at 10:19am 5°11' Sagittarius is Ascending, and the next minute at 10:20am 5°11' Gemini is Ascending. At 1:52pm, 24°49' Capricorn is Ascending, and at 1:53pm 24°49' Cancer is Ascending. The degrees from 5°12' through 24°48' Cancer, and from 5°12' Sagittarius through 24°48' Capricorn, never rose during that day, since they never touched the Horizon. When intermediate house cusps are defined assuming that all degrees touch the Horizon during a day, the system fails at polar latitudes where the assumption is invalid. In addition, there are moments when the traditional astrological Ascendent does not exist, and even the Midheaven can be regarded in two different ways. [Note: The research for this article used WinStar 2.05, which shows the Ascendant jumping 180 from Sagittarius to Gemini, and from Capricorn to Cancer. Kepler 7.0 and Sirius 1.0 show the Midheaven crossing the Ascendant instead, as shown in the wheels in the article An Astrological Dilemma: Polar Latitudes. (7) The programs show the problem to exist at slightly different times and different ways, but whatever charting program one uses, there definitely is a serious problem.]
So, why did the Placidus House System become so popular?
First of all, during the Renaissance in Europe when astrology experienced a revival, many people were not highly trained in mathematics. The Placidus House System has one very convenient characteristic: the positions of the house cusps at different times and latitudes can easily be listed in a table, and one can calculate the needed cusps by simply interpolating between neighboring values in the table. Computation is quick and easy, and requires only simple mathematics. Thus it was easy for those of moderate means and education to construct horoscopes.
The Placidus House System also became popular because, in astrological practice, it actually works quite well. Interpretations of horoscopes bear out.
The Alcabitus, Campanus, Horizontal, Poli-Equatorial, and Regiomontanus House Systems are similarly undefined for latitudes above the Arctic Circles. None of these House Systems can be used for nativities or events in polar latitudes. The Sunshine House System depends on sunrise and sunset, so the Ascendant and Descendant are normally not 180° apart, and houses are undefined for polar areas when there is either no sunrise or no sunset on a given day.
Since people are born and events occur within the Arctic Circles as well as over the rest of the Earth, is it not reasonable to expect the science and art of Astrology to be able to be applied all over the globe? And is it not reasonable to expect a scientific discipline to adopt a single house system for all latitudes, rather than switch systems? There is indeed a natural "discontinuity" at the poles. At certain times it is natural to expect horoscopes for extreme latitudes to have some asymmetries, which reflect the asymmetries in Nature at these locations. But one ought be able to construct a horoscope for very high latitudes, which are inhabited. In fact, there is good reason to believe that the science of Astrology that has been handed down to both East and West originated within the Arctic Circle, near the North Pole, before the last glaciation.(1)
So, what House Systems can be used? The Equal House System, with exactly 30° in each house, is popular, and is almost universally used in Indian Astrology. There are many variations: one places the cusp of the 1st house on the Ascendant; another places it at 0° of the major constellation in which the Ascendant falls, another places the cusp of the 10th house on the Midheaven. The Equal House System is nice and logical. Human minds love symmetry. We use symmetry in order to measure space and time, and to build houses, bridges, and spaceships.
However, Nature is not usually symmetrical. The period of daylight between sunrise and sunset varies from 5½ hours to almost 18½ hours in Oslo, Norway, and from 10½ hours to 13½ hours in Mazatlan, Mexico at the Tropic of Cancer. The Earth is slowing down slightly in its orbit around the Sun. An individual crystal may resonate with a constant frequency, but another crystal with identical specifications has a slightly different resonant frequency (thus, different accuracies of wristwatches).
If the Earth's axis were not tipped, the Ecliptic and Equator would lie in the same plane, and we could easily divide the globe into 12 sections, like an orange, to form astrological houses. However, Nature has inclined the Earth's poles at 23.44° to the Ecliptic (in 2000), and the degree even changes slightly. This tilt is actually what gives us seasons, the Arctic Lights, and many other delightful physical phenomena.
It has also led to astrological confusion, because there are many ways of dividing the globe into orange-like sections. Most of these methods draw Great Circles on the Earth, divide one of them into 12 equal sections, and then project those 12 points onto the Ecliptic to form the 12 house cusps. However, there are always problems either near the Poles or the navels of the orange, or they simply don't work well in astrological practice. There are also problems with how to define conjunctions. Some systems use divisions of time rather than space to form the house cusps. Many great minds have proposed solutions to this puzzle.
It is easy to treat the question as one of geometry alone. However, astrology requires both technical rigor and intuition, "feeling." What we are modeling is not just geometry, but an experience-sensory, experiential, feeling. We feel something special at sunrise. We feel something special when a planet is right overhead. We know-with feeling, not with physics-that planets at special places at a given moment have significance. Rigorous research has actually born out this significance.
The best possible solution might be different than we expect. We should neither reject a proposal outright because it is counter-"intuitive," nor adopt a proposal without due testing. It is important to heed the measurements that underlie our art, and also to heed our experience. A horoscope represents a 3-dimensional sky projected onto a 2-dimensional map. There are inherent limitations in collapsing data in such a manner, but yet, useful material has been gleaned from horoscopes for thousands of years and the best house system is worth pursuing.
Experiment is the test in science. When we have a theory, we subject it to a well-designed experiment. In Astrology, this means constructing a natal horoscope with various house systems, applying basic, simple and well-accepted interpretative principles, and then determining whether the results are accurate and reliable, for a large number of people.
We must test a house system using principles of natal Astrology first. Of what use is a house system that might explain many events for one person using a particular method of prediction, when it cannot even construct a natal horoscope for little Andrey? Or for the millions of people who have been born above the Arctic Circle? Natal astrology is time-tested and universal, and is thus the best measurement tool for house systems. There is little point in testing predictive methods that utilize house cusps until we have house cusps we can trust.
It is indisputable that the Ascendant is of great significance in Astrology. The Ascendant is the most potent feature of the sky at any moment of time, and the zodiacal position is related to physical appearance and presentation in the world. Prolific research has documented that planets near the Ascendant are significantly correlated with personality.(2) It is also well-researched and well-accepted that the Midheaven is very significant astrologically, especially regarding a person's public persona and achievements.
It is impossible for any Equal House System to place both the Ascendant and Midheaven prominently in a chart (unless the event occurs right at the Equator). If the Ascendant is at the cusp of the 1st house, the Midheaven is not at the cusp of the 10th, and vice versa.
In any Equal House System, at least 11 of the 12 house cusps do not depend at all on latitude. In today's world with over 130 million babies born per year on the Earth's land mass (28% of her surface), using an Equal House System means that around 60,000 people have the same horoscope! This is because the Ascendant takes an average of 2 hours to go through one sign, so the same signs will be on the house cusps. Every fraction of an hour a planet or two may change houses, but still, thousands of people have identical horoscopes when an Equal House System is used. One needs to be not just an astrologer but a Prophet in order to draw individually meaningful interpretations and forecasts when an Equal House System is used. In addition, one must decide whether the pole of the house cusps is at the N-S Poles, the poles of the Ecliptic, or somewhere else.
It is reasonable that a horoscope should depend on latitude. The Ascendant, a chart's most prominent feature, depends strongly on latitude. Days and nights are of very different durations, again depending on latitude. The houses of a horoscope roughly follow the course of a day: the 12th house from daybreak to around 8am, when we wake up and start a new day, the 11th house from 8 to 10am when we associate with others to work in hope of attaining our goals, the 10th house from 10am to noon when our public appearance (and the Sun) is prominent, and so on. At high latitudes when days are very short or long, it is not unreasonable that the houses of a horoscope be skewed, with some very large and some very small.
Notwithstanding these objections, I tried out the Equal 1st=Asc House System. It did not take long to see that the 10th house in this System was not a very good indicator of profession and public impact, matters that have always been associated with the 10th house. The Midheaven often appears in houses 8, 9, or 11 in this system.
Some astrologers avoid the problem of House System altogether by using a heliocentric system, in which the Sun is at the center of the chart rather than the Earth. A heliocentric horoscope is identical for not only all people born within a couple of hours, but a couple of days! It may be useful in considering grand, general questions, but a heliocentric system is unable to address mundane matters, which represent the most important uses of Astrology.
In order for Astrology to distinguish events and make predictions, it must: 1) differentiate house cusps based on both latitude and longitude; and 2) differentiate very small arcs. (More on this second point in a future article.)
The next reasonable proposals for House Systems are the Porphyry, Sripati, and Natural Gradation Systems. In the Porphyry House System, the cusp of the 1st house is the Ascendant, and the cusp of the 10th house is the Midheaven. Two of the resulting quadrants are larger than 90°, and two are smaller than 90°. Each quadrant is then divided into 3 equal segments to form 12 houses, six larger and six smaller ones. One must still decide where the pole of the house cusps is, but the system is quite logical so I tried it out in practice for several months. To my disappointment, it did not yield very accurate interpretations.
The Sripati House System, used by the ancient Indian mathematician Sripati, is identical to the Porphyry House System except that it places the Ascendant at the center of the 1st house and the Midheaven at the center of the 10th house. Even in the ancient Indian Equal House System, the cusp is treated as the beginning of the house rather than the center. So the Sripati System is less practical than Porphyry.
Next I tried the Natural Gradation House System, which is even more logical than Porphyry. Again the cusp of the 1st house is the Ascendant and the cusp of the 10th house is the Midheaven. The arc in between is bisected, and this point becomes the center of the 11th house, or "11th axis." Similarly, the arc between the Nadir and Ascendant is bisected, and this point becomes the center of the 2nd house. These two axes are always 90° apart. Then a particular arc, which depends on the total arc of the quadrant, is subtracted from the 11th axis to obtain the cusp of the 11th house and added to the axis to obtain the cusp of the 12th house. The cusps of the 2nd and 3rd houses are obtained identically, only that the particular arc is different because the total arc of the quadrant is different.
This System is quite satisfying because the sizes of the houses, although unequal, go smoothly from smaller to larger, rather than jumping from 3 houses of one size to 3 houses of a different size. This System reflects Nature as gradually changing and asymmetric. Although pleased at the appearance of charts in the Natural Gradation House System, I was again disappointed: it also did not yield very accurate interpretations.
The following table summarizes 24 different House Systems. The primary reason for rejecting each is indicated in bold red.
The only two House Systems left are the Birthplace House System, developed by German Astrologer Dr. Walter Koch after becoming disillusioned with the Regiomontanus System, and the Topocentric House System developed by Wendel Polich and Nelson Page in Argentina in 1961. These depend on both time and space to determine intermediate house cusps.
In the Birthplace House System, one finds the sidereal time when the degree at the Midheaven was on the Ascendant, divides the difference by three, and then adds 1, 2, 4 and 5 times this time interval to the sidereal time at birth to obtain the intermediate house cusps. It is thus is undefined for polar latitudes at some times. I had already used the Koch Birthplace House System for several years, and had abandoned it because it simply did not yield interpretations as accurate as Placidus. Research led me to try different house systems.(3)
Finally, I discovered an actual description of the Topocentric House System, "by accident" and in a completely unexpected place.(4) At most latitudes its house cusps are extremely close those of the Placidus System. Calculation by hand is time-consuming because each house cusp must be determined separately at a different "pole," or latitude.
Instead of looking at the Earth from outer space, drawing Great Circles on it and dividing them in various ways as other house systems do, the Topocentric House System looks at the heavens from the point of view of someone standing at the location itself. With the location fixed in our reference frame, the Earth rotates around an axis parallel to the North-South Pole once in 24 hours. This time period is divided into 12 equal sections, and the house cusps are defined as the degrees of the zodiac that are ascending at each 2-hour interval-at different poles, or latitudes. There is also a different pole of the Ascendant for polar latitudes (more on this important topic in a future article). This feature is a key point in the Topocentric House System.
What is even more significant is that the astrologers who discovered this system did not do so by contemplating the celestial-terrestrial sphere and pondering how to divide it. They discovered it by experiment! For example, Mr. Polich recorded the exact time-to the second-of every single small event that happened every day for three weeks: when he awoke, when a letter arrived, when a visitor came. Without exception, every one of over 1,000 events occurred within one minute of the time of transit of the mundane Ascendent. Numerous similar tests were conducted.
In practice, the Topocentric House System yields excellent results, in my experience even better than Placidus. Natal horoscopes, transit forecasts, and even horary charts cede their knowledge. When combined with small arcs of the zodiac, the Topocentric House System generates astounding interpretations. The astrologers who developed this System also tested it by experiment, and its success in their experience was their principle claim for adopting it. It works.
For comparison, here are house cusps for writer, critic and socialist leader George Bernard Shaw, born on July 26, 1856 at 12:55 am LMT in Dublin, Ireland, 53N20 and 6W15, according to several house systems. A wheel follows, so you may visualize the significant differences in house cusps, and therefore interpretations, using the different house systems.(6)
The proof is in the practice.
A Note on Theory
If we assume, a priori, that one or another method of primary (or secondary) directions should give correct predictions, then we must use a house system for which our primary direction is sensible.(5) So far, no combination has yet been found that works at all latitudes, and predictive systems are empirically often questionable even at lower latitudes for which they are designed. The Topocentric House System is empirical, its geometrical theory being somewhat unusual, and was designed as a result of using a debatable predictive technique; but this does not justify discarding it. Many important scientific facts have been discovered accidentally, while looking for or expecting something else. Gravity worked for ages before anyone figured out its formulas. We use gravitational formulas even though we have yet to discover its mechanism. No one would suggest that gravitational force (which is proportional to 1/r2) goes as 1/r because that's how they think it ought to go. Theory is important, but experiment gets the last word. Numerous Vedic astrologers now use the Placidus system-because it works. This is strong reason to seriously consider the Topocentric System, which has cusps remarkably close to those of Placidus, and additionally can be used at polar latitudes.
Alova began the study of Astrology at the age of seventeen and already had a feel for the subject. She has maintained a private practice in Spiritual Astrology since 1989 and is an avid researcher and ISAR member. She holds a B.A. in Chemistry and an M.S. in Physics. Contact email: email@example.com, firstname.lastname@example.org.
Posted with permission.