House systems

There are many systems of dividing the ecliptic into houses. In most systems, the ascendant (eastern horizon) marks the cusp, or beginning, of the first house, and the descendant (western horizon) marks the cusp of the seventh house.

In addition, quadrant systems (i.e. most systems except equal) use the midheaven (medium coeli) as the cusp of the tenth house and the nadir (imum coeli) as the cusp of the fourth house.

The equal house system defines houses as 30-degree sectors of the ecliptic. Except along the equator, the ascendant/descendant and midheaven/nadir axes can vary from being perpendicular to each other.

As a result, equal houses counted from the ascendant cannot in general place the midheaven on the tenth house cusp, where it would be symbolically desirable. Attempts to reconcile the concept of "quadrants" with the varying angle between midheaven and ascendant lead to more complicated house systems. These became more relevant as astrology spread from subtropical regions to higher latitudes.

In Southern Europe, first the Porphyry system was developed, and soon after it the Equal system. They were later replaced by the Arab-originated Alcabitius system. In Northern Europe, the Regiomontanus system was developed, later to be replaced by Placidus - which remains the most popular system among English-speaking astrologers. The Koch system is very popular among German speakers.

Goals for a house system include ease of computation; agreement with the "quadrant" concept (ascendant on the first house cusp, nadir on the fourth, descendant on the seventh, and midheaven on the tenth); defined and meaningful behaviour in the polar regions; acceptable handling of heavenly bodies of high latitude (a distinct problem from high-latitude locations on the Earth's surface); and symbolic value.

It is impossible for any system to satisfy all the criteria completely, so each one represents a different compromise. The extremely popular Placidus and Koch systems, in particular, can generate undefined results in the polar circles. Research and debate on the merits of different house systems is ongoing.

Placidus

This is the most commonly used house system in modern Western astrology. It is thought to have been first mentioned about 13th century in Arab literature, but the first confirmed publication was in 1602 by Giovanni Antonii Magini (1555-1617) in his book "Tabulae Primi Mobilis, quas Directionem Vulgo Dicunt".

Later it was popularized by Catholic Church as an argument for Ptolemy's geocentric theory of the Solar System, in the campaign against the heliocentric theory. Placidus, a professor of mathematics, was named as its author to give it credibility to his contemporaries.

The system is based on a division of time rather than space. The times taken for each degree of the ecliptic to rise from the nadir to the ascendant, and from the ascendant to the midheaven, are trisected to determine the cusps of houses 2, 3, 11, and 12. The cusps of houses 8, 9, 5 and 6 are opposite these.

The Placidus system is sometimes not defined beyond polar circles (latitudes greater than 66°N or 66°S).

Alchabitius

The predecessor to the Placidus. The difference is that the time that takes asc to reach meridian is divided equally into three parts. The Alchabitius houses have been very popular before the introduction of the Regiomontanus houses.

Porphyry

Each quadrant of the ecliptic is divided into three equal parts between the four angles. This is the oldest system of quadrant style house division.

Although it is attributed to Porphyry of Tyros, it appears that this system was actually first described by the astrologer Antiochus of Athens, and later was cited by proponent of equal house system Vettius Valens in his 2nd century work The Anthology.

Equal

In this system, the ecliptic is divided into twelve divisions of 30 degrees. This system can be computed for all locations on earth, though it's usabality in latitudes higher than 35 degrees was highly disputed in history, which led to proposal of all the others house systems as alternatives to it.

One popular criticism of this method, however, concerns the location of the Medium Coeli (Midheaven), the highest point in the chart. Since this point is associated with ambition, career, and public image, it has been linked with the tenth house and, by extension, Capricorn (the tenth sign of the zodiac). The argument is that the Midheaven, therefore, must be the cusp of the tenth house. Because the Equal House system does not take the Midheaven into account (and relies on the location of the Ascendant), it can be found anywhere between the 1st and 12th houses.

Whole sign

In the whole sign house system, the houses are also 30° each, but instead of beginning at the ascendant, the first house begins at zero degrees of the zodiac sign in which the ascendant falls.

In other words, each house is wholly filled by one sign. This is the system used in Jyotish (vedic astrology), and Hellenistic astrology. It is believed to be the oldest system of house division.

Regiomontanus

The celestial equator is divided into twelve, and these divisions are projected on to the ecliptic along great circles that take in the north and south points on the horizon.

Named after the German astronomer and astrologer Johann Müller of Königsberg.

Meridian

Similar to the above, except that the east point is taken as the ascendant.

Campanus

The prime vertical (the great circle taking in the zenith and east point on the horizon) is divided into twelve, and these divisions are projected on to the ecliptic along great circles that take in the north and south points on the horizon. It is named after Johannes Campanus.

Koch

A rather more complicated version of the Placidus system, built on equal increments of Right Ascension for each quadrant. The Koch system is defined only for latitudes between 66°N and 66°S.

This system is popular among research astrologers in the U.S., but in Central Europe lost some popularity to the Krusiński house system.

Topocentric

This is a recent system, invented in Argentina, that its creators claim has been determined empirically, i.e. by observing events in people's lives and assessing the geometry of a house system that would fit.

The house cusps are always within a degree of those given in the Placidus system.

The geometry is somewhat complicated and the reader is referred to this site for an explanation. The topocentric system can also be described as the an approximation algorithm for the Placidus system.

Krusinski

A recently published (1995) house system, based on a great circle passing through the ascendant and zenith. This circle is divided into 12 equal parts (1st cusp is ascendent, 10th cusp is zenith), then the resulting points are projected to the ecliptic through meridian circles (circles passing through the equatorial north and south poles, perpendicular to equator, see: meridian (geography)).

The house tables for this system were published in 1995 in Poland. This house system is also known under the name Amphora in the Czech Republic, after it was scholarly proposed there by Milan Píša after the study of Manilius's "Astronomica" under this name ("Konstelace č. 22" in: "AMPHORA - nový systém astrologických domů" (1997) and in the booklet "Amphora - algoritmy nového systému domů" (1998)).

Rulership

In Hellenistic, Vedic, Medieval and Renaissance astrology each house is ruled by the planet that rules the sign on its cusp.

For example, if a person has the sign Aries on the cusp of their 7th house, then the planet Mars is said to "rule" their 7th house. This means that when a planet is allotted a house, its nature comes to have some bearing on that specific topic in the person's life, and that planet is said to be very important for events specifically pertaining to that topic.

The placement of this planet in the chart will have at least as much influence on the chart as the planets within the house. In traditional Western & Hindu astrology, each sign is ruled by one of the 7 visible planets (note that in astrology, the Sun and Moon are considered planets, which literally means wanderers, i.e. wandering stars, as opposed to the fixed stars of the constellations).

In addition, some modern astrologers who follow the planet=sign=house doctrine, which was first taught by Alan Leo in the early part of the 20th century, believe that certain houses are also "ruled" by, or have an affinity with, the planet which rules the corresponding zodiacal sign.

For instance, Mars is ruler of the 1st house because Aries is the first sign, Mercury rules or has an affinity with the 3rd house because Gemini is the 3rd sign, etc. This is sometimes referred to as "natural rulership", as opposed to the former which is sometimes called "accidental rulership".

Why Twelve Houses?

The majority of astrologers use a 12 house division. But one theoretician, Patrice Guinard, Ph.D. [1] has argued, based on historical records, that there is a basis for an 8 house division.

One prominent astrologer, Marc Penfield, uses 8 houses - dividing each quadrant using the same technique as in Koch & Placidus.

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01.03.2007. 13:33

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