Editing House (astrology) (section)

==Systems of house division==
[[Image:12 houses of heaven.jpg|right|thumb|This 18th-century [[Iceland]]ic manuscript drawing shows the twelve astrological houses with signs for the planetary rulership or maybe planetary joy.]]

There are many systems of house division. In most, the ecliptic is divided into houses and 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. Many systems, called quadrant house systems, also use the midheaven (''medium coeli'') as the cusp of the tenth house.

Goals for a house system include ease of computation; agreement with the "quadrant" concept (ascendant on the first house cusp and midheaven on the tenth);{{sfnp|Wickenburg|1992}} 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.{{sfnp|Holden|1982}}

===Early forms of house division===
The [[Babylonian astrology|Babylonians]] may have been the first to set out the concept of house division.{{sfnp|Parker|Parker|1990|p=12}} Specifically, they timed the birth according to three systems of time division: (a) a three-part division of the night into watches, (b) a four-part division of the [[nychthemeron]] with respect to sunrise and sunset, and (c) a twelve-part division of the day-time into hours.{{sfnp|Rochberg|1998|p=35}} Babylonian astronomers studied the rising times of the signs and calculated tables of ascensions for their latitude,  but it would take better time measurements by the Egyptians and the introduction of the concept of ascendant, around the 2nd century BC, to give astrological houses their first recognisable structure and meaning, from the perspective of Classical Western astrology.{{sfnmp|1a1=Holden|1y=1982|2a1=Tester|2y=1990|2p=25}}

====Whole sign====
<!-- This section is linked from [[Jyotisha]] -->
In the whole sign house system, sometimes referred to as the 'Sign-House system', the houses are 30° each.  The ascendant designates the rising sign, and the first house begins at zero degrees of the [[zodiac sign]] in which the ascendant falls, regardless of how early or late in that sign the ascendant is. The next sign after the ascending sign then becomes the 2nd house, the sign after that the 3rd house, and so on. In other words, each house is wholly filled by one sign. This was the main system used in the [[Hellenistic astrology|Hellenistic tradition of astrology]], and is also used in [[Indian astrology]], as well as in some early traditions of [[Arab and Persian astrology|Medieval astrology]]. It is thought to be the oldest system of house division.{{sfnp|Holden|1982|p=19-28}}

The Whole Sign system may have been developed in the Hellenistic tradition of astrology sometime around the 1st or 2nd century BCE, and from there it may have passed to the [[Jyotish|Indian]] and early Medieval traditions of astrology; though the line of thought which states that it was transmitted to India from Western locales is hotly contested. At some point in the Medieval period, probably around the 10th century, whole sign houses fell into disuse in the western tradition, and by the 20th century the system was completely unknown in the western astrological community, although was continually used in India all the way into the present time. Beginning in the 1980s and 1990s the system was rediscovered and reintroduced into western astrology.

The distinction between equal houses and whole sign houses lies in the fact that in whole sign houses the cusp of the 1st house is the beginning of the sign that contains the ascendant, while in equal houses the degree of the ascendant is itself the cusp of the 1st house.{{sfnp|Hand|2000}}

====Equal house====
In the equal house system the [[ecliptic]] is also divided into twelve divisions of 30 degrees, although the houses are measured out in 30 degree increments starting from the degree of the ascendant. It begins with the ascendant, which acts as the 'cusp' or starting point of the 1st house, then the second house begins exactly 30 degrees later in zodiacal order, then the third house begins exactly 30 degrees later in zodiacal order from the 2nd house, and so on.{{sfnp|Houlding|2006}} Proponents of the equal house system claim that it is more accurate and less distorting in higher latitudes (especially above 60 degrees) than the Placidean and other quadrant house systems.{{sfnp|Parker|Parker|1990|p=175}}

===Space-based house systems===
In this type of system, the definition of houses involves the division of the sphere into twelve equal [[Spherical lune|lunes]] perpendicular to a fundamental plane (the Morinus and Regiomontanus systems being two notable exceptions).{{sfnmp|1a1=Hone|1y=1978|1p=134|2a1=Foreman|2y=1992|2p=20}}

{| class="wikitable"
|-
! Spatial house system !! Fundamental Plane !! Division !! Reference point(s) !! Projection onto the ecliptic !! 1st cusp !! 10th cusp
|-
|- style="text-align:center;"
| Whole sign || rowspan="4"| [[Ecliptic]] || rowspan="3"| 12 equal sectors of 30° in [[ecliptic longitude|longitude]] || Rising Sign || rowspan="4"| - || 0° of rising sign || 0° of Nonagesimal sign<ref>{{harvp|Hone|1978|p=111}}: "the highest point of the ecliptic above the horizon".</ref>
|-
|- style="text-align:center;"
| Equal house || Longitude of [[Ascendant|Asc]] ({{math|''λ''}}<sub>Asc</sub>)|| {{math|''λ''}}<sub>Asc</sub> || Nonagesimal<br/>({{math|''λ''}}<sub>Asc</sub> - 90º)
|-
|- style="text-align:center;"
| M-House || Longitude of MC ({{math|''λ''}}<sub>MC</sub>) || {{math|''λ''}}<sub>MC</sub> + 90º || rowspan="2"|{{math|''λ''}}<sub>MC</sub>
|-
|- style="text-align:center;"
| Porphyry || Trisection of MC-Asc longitude arc (11th, 12th cusps)<br/>Trisection of Asc-IC longitude arc (2nd, 3rd cusps) || Longitudes of MC, Asc and [[Imum coeli|IC]] || rowspan="2"|{{math|''λ''}}<sub>Asc</sub>
|-
|- style="text-align:center;"
| Carter's Poly Equatorial || rowspan="4"| [[Celestial equator]] || rowspan="4"| 12 equal sectors of 30° in [[Right Ascension|RA]]<br/>(2 [[Hour angle|sidereal hours]]) || RA of [[Ascendant|Asc]] || rowspan="2"| Along great circles containing the [[celestial pole]]s || Not the MC
|-
|- style="text-align:center;"
| Meridian || rowspan="3"| RA of MC || [[Equatorial ascendant|East Point]]<br/>(Equatorial Ascendant) ||{{math|''λ''}}<sub>MC</sub>
|-
|- style="text-align:center;"
| Morinus || Along great circles containing the [[ecliptic pole]]s || {{math|''λ''}}<sub>MC</sub> + 90º || Not the MC
|-
|- style="text-align:center;"
| Regiomontanus || rowspan="2"| Along great circles containing the North and south points of the [[Horizontal coordinate system|Horizon]] || rowspan="2"|{{math|''λ''}}<sub>Asc</sub> || rowspan="2"|{{math|''λ''}}<sub>MC</sub>
|-
|- style="text-align:center;"
| Campanus || [[Prime vertical]] || 12 equal sectors of 30° || [[Zenith]]
|}

====M-House (Equal Mc)====
This system is constructed in a similar manner as the Equal house, but houses are measured out in 30 degree increments starting from the [[Ecliptic coordinate system|longitude]] of the midheaven (Mc), which acts as the 'cusp' or starting point of the 10th house. The ascendant does not coincide with the cusp for the 1st house.{{sfnp|Hand|2000}}

====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]], this system was first described by the 2nd-century astrologer [[Vettius Valens]], in the 3rd book of his astrological compendium known as ''The Anthology''.{{sfnp|Gansten|2023}} Martin Gansten argues that in Valens, houses were often provisionally approximated by sign position alone, but calculation of places by degree was consistently upheld in principle as more accurate and useful.{{sfnp|Gansten|2023}}

====Carter's Poly Equatorial====
This house system was described by the English astrologer Charles E. O. Carter (1887–1968) in his ''Essays on the Foundations of Astrology''.{{sfnp|Carter|1978|pp=158-159}} The house division starts at the [[right ascension]] of the ascendant and to it is added 30º of right ascension for each successive cusp. Those cusps are then restated in terms of celestial longitude by projecting them along great circles containing the North and South [[Celestial coordinate system|celestial poles]]. The 1st house cusp coincides with the ascendant's longitude, but the 10th house cusp is not identical with the Midheaven.

====Meridian====
Also known as the Axial system, or Equatorial system, it divides the celestial equator in twelve 30° sectors (starting at the local meridian) and projects them on to the [[ecliptic]] along the great circles containing the North and South [[Celestial coordinate system|celestial poles]]. The intersections of the ecliptic with those great circles provide the house cusps. The 10th house cusp thus equals the Midheaven, but the [[Equatorial ascendant|East Point]] (also known as Equatorial Ascendant) is now the first house's cusp. Each house is exactly 2 [[Hour angle|sidereal hours]] long.{{sfnp|Foreman|1992|p=31}} This system was proposed by the Australian astrologer David Cope in the beginning of the 20th century and has become the most popular system with the Uranian school of astrology. The Ascendant (intersection between the ecliptic and the horizon) preserves its importance in chart interpretation through sign and aspects, but not as a house determinant, which is why this house system can be used in any latitude.{{sfnp|Houlding|2006}}
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====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 [[Regiomontanus|Johann Müller of Königsberg]], the Regiomontanus system was later largely replaced by the Placidus system.{{sfnp|Rusborn|2023}}

====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 attributed to [[Campanus of Novara]] but the method is known to have been used before his time.<ref>{{harvp|North|1986|pp=175-176}}: "The eastern origins of the Campanus (Prime Vertical) method. Evidence from al-Bīrūnī".</ref>

====Sinusoidal====
Sinusoidal systems of house division are similar to Porphyry houses except that instead of each quadrant being divided into three equal sized houses, the middle house in each quadrant is compressed or expanded based on whether the quadrant covers less than or greater than 90 degrees. In other words, houses are smooth around the zodiac with the difference or ratio in quadrant sizes being spread in a continuous sinusoidal manner from expanded to compressed houses. Sinusoidal houses were invented and first published by Walter Pullen in his astrology program [[Astrolog]] in 1994.<ref>{{Cite web|url=http://www.astrolog.org/astrolog/astsine.htm|title = Sinusoidal House Systems}}</ref>

===Time-based house systems===

====Alchabitius====
The predecessor system to the Placidus, which largely replaced the Porphyry. The difference with Placidus is that the time that it takes the ascendant to reach the meridian is divided equally into three parts. The [[Alchabitius]] house system was very popular in Europe before the introduction of the Regiomontanus system.

====Placidus====
This is the most commonly used house system in modern [[Western astrology]]. The paths drawn for each degree of the ecliptic to move from the Imum coeli to the horizon, and from the horizon to the midheaven, are trisected to determine the cusps of houses 2, 3, 11, and 12.{{sfnp|Rusborn|2023}} The cusps of houses 8, 9, 5 and 6 are opposite these. The Placidus system is sometimes not defined beyond polar circles ([[latitude]]s greater than 66°N or 66°S), because certain degrees are ''circumpolar'' (never touch the horizon), and planets falling in them cannot be assigned to houses without extending the system. This result is a weakness of the Placidean system according to its critics, who often cite the exceptional house proportions in the higher latitudes.<ref>[http://www.astrodatabank.com/AstrologyFAQ.htm#EqualHouse Astrodatabank FAQ n.5]</ref>

Named for 17th-century astrologer [[Placidus de Titis]], it is thought the Placidus system was first mentioned about 13th century in Arab literature, but the first confirmed publication was in 1602 by [[Giovanni Antonio Magini]] (1555–1617) in his book "Tabulae Primi Mobilis, quas Directionem Vulgo Dicunt". The first documented usage is from Czech, 1627.{{sfnp|Singer|2007}}

====Koch====
A rather more complicated version of the Placidus system, built on equal increments of Right Ascension for each quadrant. The Koch system was developed by the German astrologer [[Walter Koch (astrologer)|Walter Koch]] (1895–1970) and is defined only for latitudes between 66°N and 66°S.  This system is popular among research astrologers in the U.S. and among German speakers, but in Central Europe lost some popularity to the Krusiński house system.{{sfnp|Houlding|2006}}

====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 topocentric system can also be described as an approximation algorithm for the Placidus system. Topocentric houses are also called Polich-Page, after the names of the house system creators, Wendel Polich and A. Page Nelson.{{sfnp|Houlding|2006}}

===Chart gallery===
The following charts display different house systems for the same time and location. To better compare systems subject to distortion, a high latitude city was chosen (Stockholm, Sweden) and the time corresponds to a [[Ascendant#Long and short ascension|long ascension sign]] (Cancer). For clarity purposes, all the usual aspect lines, degrees and glyphs were removed.

<gallery>
Whole Sign house divisions.jpg|Whole Sign house divisions
Equal (Asc) house divisions.jpg|Equal (Asc) house divisions
M-House house divisions.jpg|M-House house divisions
Porphyry house divisions.jpg|Porphyry house divisions
Meridian house divisions.jpg|Meridian house divisions
Morinus house divisions.jpg|Morinus house divisions
Regimontanus house divisions.jpg|Regiomontanus house divisions
Campanus house divisions.jpg|Campanus house divisions
Alcabitius house divisions.jpg|Alcabitius house divisions
Placidus house divisions.jpg|Placidus house divisions
Koch house divisions.jpg|Koch house divisions
Topocentric house divisions.jpg|Topocentric house divisions
</gallery>

===The MC in non-quadrant house systems===
In the whole sign and equal house systems the Medium Coeli (Midheaven), the highest point in the chart, does not act as the cusp or starting point of the 10th house. Instead the MC moves around the top half of the chart, and can land anywhere in the 7th, 8th, 9th, 10th, 11th, 12th, depending on the latitude. The MC retains its commonly agreed significations, but it does not act as the starting point of the 10th house, whereas the Equal house system adds extra definition and meaning to the MC including any cusps involved, any interpretations applied to the MC itself concur with other house systems.{{sfnp|Hand|2000}}

This is also the more common criticism of the whole sign and equal house method as it concerns the location of the Medium Coeli (Midheaven), the highest point in the chart. In the equal house system, the ascendant/descendant and midheaven/IC axes can vary from being perpendicular to each other (from approx. +-5 deg at most at equator to approx. +-15 degrees at Alexandria to +-90 degrees at polar circle). As a result, equal houses counted from the ascendant cannot in general place the midheaven on the tenth house cusp, where many feel it would be symbolically desirable. Since this point is associated with ambition, career, and public image, the argument is that the Midheaven, therefore, must be the cusp of the similar tenth house. It has also been linked by extension with Capricorn (the tenth sign of the zodiac). The equal house system always takes the MC to be first and foremost THE most important indicator of career; whereas the 10th house cusp, while taken into account, is interpreted simply as a weaker 2nd MC cusp. The Midheaven is not associated with house locations defined by the Whole Sign and Equal House system, rather, the Midheaven placement relies on the specific location of the Ascendant, so the Midheaven can be found anywhere between the 8th and 11th houses.{{sfnp|Mayo|1979|p=76}}