Introduction to Houses Kepler College ES-174 ©2008 J. Lee Lehman

Houses John & Peter Filbey. 1986. The Astrologer's Companion. Aquarian Press: Wellingborough. Michael P. Munkasey. 1988. An Astrological House Formulary. NCGR Journal: Winter 1988-9: pp 37-45 J. D. North. 1986. Horoscopes and History. Warburg Institute: London.

Houses and the Babylonians The Babylonians provided the basis for houses in developing systems for calculating the Ascendant and Midheaven. The Babylonians produced tables of rising times, which were the key to understanding the "problem" of houses.

Houses in the Hellenistic Period The Greeks typically used the Whole Sign House system, in which one sign is completely equivalent to one house, with the first sign (house) being the sign of the Ascendant. Despite the ability to accurately determine the Ascendant and Midheaven, full listings of house cusps are rare from this period. Common systems found are the standard method-5°, dual longitude method, and the single longitude method.

Ecliptic-based House Systems Equal House Whole Sign Houses Porphyry Recent variants: the Natural Gradation System and M. House method

Equal House Method The Ascendant (or in some cases, the Midheaven, or some other point) is calculated, and then all other cusps are computed as beginning 30° from that calculated cusp.

Whole Sign Houses In the Whole Sign house system, the Ascendant is computed. The 1st House begins with the sign of the Ascendant, and each succeeding house is the succeeding sign.

Porphyry House System The arc of the ecliptic between the MC and Ascendant is trisected, or between the Ascendant and IC. This produces Equal Houses at 6 am and 6 pm. Dates from 3rd Century CE.

Time-based House Systems Alcabitious Systems Classical System Natural Hours Placidus Koch Topocentric

Alcibitius Declination House System "(Sometimes spelled 'Alcabitius'). The diurnal arc of the ascendant is trisected and projected by hour circles onto the ecliptic to form the house cusps." (MPM) This is called the "standard method" in North.

AIcibitius Semi-Arc House System "The diurnal arc of the ascendant is trisected and projected by vertical circles onto the ecliptic to form the house cusps." (MPM)

Classical House System "The diurnal arc of the ascendant is trisected and projected by hour circles onto the ecliptic to form the house cusps, but 5° is subtracted from the ASC to form the first house cusp. This slight correction to the Alcibitius Declination house system described above was used in antiquity to correct for observational effects due to atmospheric refraction close to horizon." (MPM) This is called the "standard method with the five degree shift" in North.

Natural Hours House System "The times of sunrises and sunset are noted for the location and date of the horoscope. The degrees of the ASC at Sunrise and Sunset give the degrees of the ascendant and descendant respectively. The hemispheres between the ASC and DSC are divided into six sectors, each representing two 'hours' of time. These sectors also give the house cusps. Note that the ascendant and descendant are no longer tied together as a pair in this system, and the MC may fall in any house." (MPM)

Placidian House System "The celestial equator circle is cut at 30° intervals starting at the Aries point, and these points are projected onto the ecliptic using house circles. The original cusps are then recalculated in a complicated adjustment cycle which continues until no further cuspal movement is perceived." (MPM) This system works by trisecting the semi-arc of each degree of the Ecliptic.

Koch House System A variation on Alcabitious, using the trisection of the diurnal arc of oblique ascension from Horizon to Ecliptic. Devised by Walter Koch

Topocentric House System "This is a very slight mathematical variation of the Placidian algorithm, which, supposedly, allows for a more accurate calculation of the intermediate house cusps in the polar regions.“ (MPM) Developed in the early 1960's by Wendel Polich and A. P. Nelson Page

Meridian House System "The celestial equator circle is cut at 30° intervals starting at the Aries point, and these points are projected onto the ecliptic using hour circles." (MPM)

Space-based House Systems Campanus Regiomontanus Morinus

Campanus House System "The prime vertical is cut at 30° intervals starting at the east point of the horizon, and these points are projected onto the Ecliptic using house circles." (MPM) “[This] was widely used in Iran as early as the 11th century... Biruni claimed that he invented it.” (Kennedy: 155)* * Kennedy, E.S. 1990. Ibn Mu'ādh on the Astrological Houses. Zeitschrift Gesichte de Arabisch-Islamischen Wissenschaften 9. Frankfurt am Main, pp 153-160.

Morinus House System "The celestial equator circle is cut at 30° intervals starting at the Aries point, and these points are projected onto the ecliptic using longitude circles." (MPM)

Regiomontanus House System "The celestial equator circle is cut at 30° intervals staffing at the Aries point, and these points are projected onto the ecliptic using house circles. This is similar to the Placidian house system, but without the complicated adjustment algorithm required by that method." (MPM) Ibn Mu`ādh clearly defined this system in the 11th century.* * Kennedy, E.S. 1990. Ibn Mu'ādh on the Astrological Houses. Zeitschrift Gesichte de Arabisch-Islamischen Wissenschaften 9. Frankfurt am Main, pp 153-160.

Vedic Houses Most Vedic astrologers use what we would now call the whole sign house system. Sometimes the Ascendant is taken as the middle of the house, with the houses consisting of zones 15° before and after the Ascendant, projected in an equal house system from the 1st house. An unequal house system called Sri Pati that is equivalent to Porphyry is also sometimes used.