User:Aditya soni/WorkinProgress/The Sign-wise Equal house division of the Zodiac or Rasi-chakra

 The Sign-wise Equal house division of the Zodiac or Rasi-chakra is a very old system of house division; in this system all houses are of equal length. Unlike the Western astrology that measures the longitude of a house from the exact ascendant-point in the sign rising in the east treated as its cusp, in Hindu astrology the entire sign is treated as a house irrespective of the ascendant-point in the sign rising in the east. The standard Hindu convention is to treat the house and the sign of equal length. It considers the twelve houses in the fixed Rasi-chakra (Zodiac), and is practically an "Equal-sign Equal house system". Hindu astrology is sidereal astrology , in which system planetary movements are tracked against the fixed position of the stars or nakshatras; it is believed to give a more accurate astronomical representation of the Sun’s position in relation to the skies i.e. the Zodiac, using the Ayanamsa (amount of precession), and incorporates star-signs based on the movement of the Moon.

Vedic concept
The Vedic Rishis were aware of the Zodiac (Rig Veda I.164.48) which awareness echoes in the Atharvaveda (Mantra X.viii.4) as :-


 * द्वादश् प्रधयश्चक्रमेकं व्रीणि नभ्यानि क उ तच्चिकेता |
 * तव्राहतास्व्रीणि शतानिशंकवः षष्टिश्चखिला अविचाचलायो ||

the Rishi speaks about the wheel of twelve spokes, which has three navels with three hundred sixty nails. The spokes are the twelve Solar months or twelve Zodiacal signs or rasis, the three hundred sixty nails are the three hundred sixty degrees of the Zodiac, and the three navels are the three sets of Chaturmasas (Four months x three) that make up a year. The horoscopic picture (birth-chart) is the superimposition of the Space-divisions over the Elliptical orbit; the four vertical and horizontal lines (in the South Indian chart) that intercept the orbit lead to a four-fold division of space in two dimensions leading to a periphery of twelve columns or houses and a near quandrular demarcation that depicts a two-fold division. This picture is evident from Parasara’s description of the Kala Chakra and Jaimini’s Rasi aspects. The mathematical features of the sequence of peripheral divisions through the three-fold, four-fold and five-fold divisions; the superimposition of these space-divisions onto a curvilinear path yields the divisions 4, 8, 12, 16, 20, 24, 28…., or 4(n-1) division of the periphery for an n-fold division of space – n=(1+3 I). The nakshatra-divisions of the Zodiac are only twenty-seven in number and the real mathematical process was a division of the ecliptic into one hundred eight parts of three degrees twenty minutes each (equal to one navamsa or 1/9th division of a sign) which fact is corroborated by Maitrayaniya Upanishad (VI.14) which tells us that – "Time beginning with the moment to the twelve-fold-natured-year is the form the Sun bears. Half of the year belongs to fire and half belongs to water. From the beginning of Makha (120 degrees) to the middle of Sravista (300 degrees) belongs to fire (Agni)(clockwise). Step by step from the end of Sarpa (120 degrees) to the middle of Sravista belongs to water (300 degrees – anticlockwise). Then by subtlety are the single parts of time, the navamsas, together with the moving ones (the planets), by this measure time (the year) is measured."

Rasi-chakra or Zodiac
The Zodiac or the Bhachakra is composed of three hundred sixty degrees of the celestial space which is divided by twelve to mark the twelve equal Zodiacal signs or rasis. Rasi-sandhi is where two signs join. The longitudes of the houses (bhava sphutas), rasimanas (oblique ascensions or rising periods of the twelve signs) and other important calculations are all computed for Sayana rasis (tropical position), from these the Ayanamsa is subtracted and the Nirayana bhavas etc., are obtained. Rasi-chakra is simply a figure of the fixed zodiac with the limits and occupants of its twelve signs as well as the lagna clearly marked. Bhava-chakra is the division of the heaven into twelve houses with reference to time and space. According to Hindu astrology, a bhava means one-third of the arc of the ecliptic intercepted between any two adjacent angles, viz., the Udaya lagna (Eastern Horizon), the Patala lagna (Lower Meridian), the Asta lagna (Western Horizon), and the Madhya lagna (Upper Meridian). Bhava-sandhi is where two bhavas join.

Hindu astrology is primarily based on constellations or nakshatras, the longitudes of constellations differ from place to place but for purposes of predictive astrology each constellation is treated as having a jurisdiction of thirteen degrees twenty minutes i.e. the zodiac divided by twenty-seven nakshatras or 360 degrees divided by 27; the word, sidereal, pertains to the zodiac of the constellations of the fixed stars. All signs are as in the fixed zodiac and the longitudes of planets also refer to their location on the fixed zodiac. According to older Hindu texts, the words signs and houses fall on each other, but the count of the signs is always made from Aries which is the first sign, and the count of the house begins from the lagna; the duration of a sign rising differs from latitude to latitude.

Ashwini nakshatra marks the beginning of the Zodiac, Revati, placed exactly on the Ecliptic, identifies this constellation as zero degree Aries and marks the divergence of the point of the Vernal Equinox from it but its own identity is in doubt. Therefore, Chitra or 'Alpha Virgo', a far brighter star is taken to fix the position of Revati exactly one hundred eighty degrees away from Chitra. Surya Siddhanta position is the traditional basis of the Chitra Paksha Ayanamsa.

Significance
Hindu astrology is based on the whole sign equal to one house principle. The principle of dividing the zodiac into twelve equal parts relates to the original Whole sign houses system. The advantage of this system is that the houses (bhavas) are easier to calculate, and it is easier to read the planetary combinations and permutations i.e. the yoga-formations, planetary aspects and other harmonic divisional results. The  lagna  determines the entire field of action, through it are interpreted all the different aspects of life. According to Hindu astrology the sign ascending is the first house and any planet placed therein is deemed to be in the first house; the sign next to the ascendant will constitute the second house and any planet placed therein is deemed to be in the second house. The sign and house are deemed synonymous. All yogas given in ancient Hindu astrological texts are based on this principle; Parasara, Jaimini, Mantreswara, all followed this method of house division. Therefore, Gopesh Kumar Ojha recommends this method, which is simpler and favoured by majority, should be followed. In the Parashari system of Hindu astrology a sign is equal to a bhava or house. Planets involved in mutual exchange of signs or Parivartana yoga i.e. each occupy the other’s house, give rise to auspicious and inauspicious yogas. The mutual exchange of signs between lords of favourable bhavas viz the lords of the 2nd, the kendras, the trikonas and the 11th bhava, are said to produce twenty-eight auspicious yogas known as Maha yogas; those born with Maha yogas are most fortunate and wealthy. The mutual exchange of the lords of the these bhavas with the lord of the 3rd give rise to eight inauspicious Khala yogas but the lords of the 6th, the 8th and the 12th, which are known as the Trika bhavas, as involved between themselves and all other bhava-lords give rise to thirty very inauspicious Dainya yogas.