Most western astrological systems divide the astrological chart (or natal chart) into a number (usually twelve) houses, which depend on the time and place of birth (or initiation) rather than on the date. The houses are divisions of the sky ( including that part of it hidden to us by the Earth beneath our feet) and are usually numbered from the position of the eastern horizon at the time of the observation. There are a range of approaches to calculating these divisions and a wide variety of opinion among astrologers over which house system to use.

To calculate the houses of a chart it is necessary to know the exact time of birth. If the time of birth is unknown some astrologers will use a birth time set for noon or sunrise, but an meaningful interpretation of such a chart cannot be expected.

The houses are departments of life, described in terms of man's physical surroundings as well as personal life experiences, and many modern astrologers assume that they have some correspondence with their natural sign, i.e. the first house has a natural affinity with the first sign, Aries, and so on.

In quadrant systems houses are classified as angular (1st, 4th, 7th, and 10th), succedent (2nd, 5th, 8th, and 11th), and cadent (3rd, 6th, 9th, and 12th). Angular houses represent the potential for action, succedent houses give stability and purpose, cadent houses are communicative and enable change or adaptation.

In old astrological writers (e.g. William Lilly), house could also be used as a synonym for domicile or rulership, as in the sentence "The Moon has its house in Cancer" - meaning that Cancer is ruled by the Moon.

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 aloted a house, it's 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 as the chart as the planets within the house. In traditional Western & Hindu

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, eg. 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., and this is sometimes referred to as "natural rulership", as opposed to the former which is sometimes called "accidental rulership".

The traditional rulerships are as follows: Aries (Mars), Taurus (Venus), Gemini (Mercury), Cancer (Moon), Leo (Sun), Virgo (Mercury), Libra (Venus), Scorpio (Mars), Sagittarius (Jupiter), Capricorn (Saturn), Aquarius (Saturn), Pisces (Jupiter).

The majority of modern western astrologers believe that Uranus is the ruler of Aquarius instead of Saturn, Neptune is the ruler of Pisces instead of Jupiter, Pluto is the ruler of Scorpio instead of Mars, while Venus and Mercury still have dual rulership of Taurus & Libra and Gemini & Virgo respectively. Some modern astrologers reject the dual rulerships all together and assign no planets to Taurus and Virgo. Some astrologers treat the new planets as co-rulers of the signs in addition to their traditional rulers (or vice-versa), while others who practice more traditional forms of astrology often opt not to assign the outer planets sign rulership at all. Traditional (Hindu) astrology strictly adheres to the traditional rulerships system listed in the paragraph above, and the debate continues between those astrologers those who consider the newly discovered planets as only rulers or even corulers of certain signs and those that do not or opt for them to be rulers at all.

Traditionally, a planet is said to be strengthened (dignified) if it falls within the astrological sign that it rules. If a planet is in the sign opposite that which it rules, it is said to be weakened (detriment).

Signification

• First house: Identity, self-image, movement and expression, physical appearance, and the impact of the personality on the environment. This is the way you present yourself, and how you start things. Planets here may also indicate the manner of one's birth.

• Second house: Values, substance, money, possessions, security, stability, the here and now, sense of self-worth, emotional resources, rewards, comfort, inner talents and resources.

• Third house: awareness, mental expression, early schooling, siblings, attitudes, daily life, companions, all forms of communication and short journeys, adaptability to new ideas, ability to relate to one's surroundings and environment.

• Fourth house:
  
  
  
  Home, foundations, parents, domestic matters, heritage, roots, sources of nourishment.

• Fifth house: Anything added or taken away from the fourth house, children, romance and love affairs, ego, creative expression, play and gambling, attitude to change.

• Sixth house: Housework, employment and employees, attitude to work, general health, purification, ritual, habits, hobbies.

• Seventh house: All kinds of partnerships, marriage, awareness of others, how one relates to people.

• Eighth house: Joint or shared resources, sex, inheritance, sex and regeneration, emotional union.

• Ninth house: Travel, religion, search for meaning, higher education, goals and aspirations, seeking and finding.

• Tenth house: Public image, profession, persona, reputation, values and standards, ideals, how one would like to project oneself.

• Eleventh house: Friends, social values and concerns, groups and group awareness, hopes and dreams, attitude to humanity.

• Twelfth house: Hidden motives, confinement, retreat, self-transcendence, service and sacrifice, escapism, charity.

House systems

There are many ways to divide the ecliptic into twelve houses. In most systems, the ascendant (eastern horizon) marks the beginning (cusp) 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 House) use the midheaven (MC) as the cusp of the tenth house and the imum coeli (IC) as the cusp of the fourth house.

Most quadrant systems fail or exaggerate the house sizes when a chart is drawn for a location in extreme northern or southern latitudes, but since these births are comparatively rare, this does not seem to worry most astrologers.

There are dozens of house systems now available for modern astrologers to choose from; the following is only an incomplete list. (please add to it)

Placidus

The most commonly used house system in modern Western astrology. There seems to be no particular reason for its popularity except that calculation tables have always been easily available. The system is based on a division of time rather than space as in most other systems. The times taken for each degree of the ecliptic to rise from the IC to the ascendant, and from the ascendant to the MC, 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 defined only for latitudes between 66°N and 66°S.

Equal

The ecliptic is divided into twelve divisions of 30 degrees each. As long as there is an ascendant, twelve equal houses can be measured from it, so this system works for all locations although there will be anomalies in charts for locations within the polar circles.

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.

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 Vettius Valens in his 2nd century work The Anthology.

Koch

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

Topocentric

View 1:This is a recent system, invented in Argentina, that its creators claim to have 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, which would seem to corroborate that system. The geometry is somewhat complicated and the reader is referred to .

View 2:Placidus house system computed by space division algorithm, instead of Placidus's original time based algorithm. Thus Topocentric house cusps positions differ by up to 1 degree from original Placidus, eliminating error introduced by time based alg., giving exact position of house cusps.

Explanation: Topocentricity mentioned in above linked article applies to objects like Sun, Moon and planets and their house positions. For house cusps positions there's no difference between topocentric or geocentric ones.

Krusinski

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