Overview of Jyotisa or Vedic Astrology
Vedic Astrology is a moon school tradition that employs a version of the lunar mansions called nakstras, that are similar to the sieu of Chinese astrology. These are used to delineate the natal chart and “personal chronological development”.
Vedic tradition includes three unique facets. Vedic astrologers employ a specialized lunar chart in the development of a womanize personality profile. It is also more mathematical than Tibetan or Chinese Astrology. Lastly the Vedic astrologer create a personality chronology that tracks activities to months and days without predictive techniques like Chinese and Tibetan astrology.
Vedic astrology basically focuses on Karmic debt and accumulated merit from past lives.
There are five basic subdivisions of Vedic astrology:
1.) Jakata natal chart
2.) Prasna hooray charts
3.) Varshaphala predictive astrology
4.) Muhtra electoral
5.) Yatra mundane astrology
Each subdivision has numerous methods and variations for the calculation and interpretation of data. There are sixteen sodasavarga (some times shortened to vargas) or divisional charts representing specific areas of life such as destiny, marriage, education, luck etc. and subdivides the 30 degrees of each zodiac sign into smaller increments of degrees and minutes. Not all of the Vargas are consulted regularly. Most common are: rasicakra (sign chart) or bhavacakra (house chart); horacakra (half sign chart), drekandacakra (third-sign chart), saptamsacakra (seventh-sign chart), navamsacakra (ninth-sigh chart), dasamsacakra (tenth-sign chart), and dvadsacakra (twelfth-sign chart) that are used in the jakata. The complexities of construction and interpretation can be enormous and can fill volumes of books when one includes additional charts and their subdivisions.
Much of the knowledge concerning interpretation of each chart type has only been passed on by oral tradition and is carefully guarded by master astrologers.
For women a specialized Moon chart called candralagna is used. It is common in Vedic as well as Chinese and Tibetan astrology to not include the outer planets of Uranus, Neptune and Pluto as well as Chiron and the asteroids because they were not visible in Vedic times. Some modern Vedic astrologers include them in their work. Yet different from Chinese and Tibetan (which are closely related) the Vedic system treats the north and south nodes of the moon like planets even though they are not celestial bodies. They are called Rahu and Ketu respectively.
The basic difference in calculating a Vedic chart from a western chart is that it is calculated from the sidereal zodiac not the tropical zodiac. The easiest way to develop a jatuka is to begin with a western chart and convert it by subtracting the degrees and minutes of ayanamsa from the Ascendant and from each planetary position. For this you need a chart of years and calculated ayanamsa. Between 1924 and 2050 the ayanamsa ranges from 22deg. 42min. To 24deg. 28min. So to estimate you Vedic house cusps and planetary positions subtract 23 deg. from their western positions.
For beginners the best way to interpret the meaning of the positions is to use charts from Books of Vedic Astrology. Still like all forms of astrology the best way to learn is to use and reflect upon you own chart. You know yourself better than anyone else does so your chart is just an abstraction of you and your life. Astrology is a language and a tool to understand the forces and energies at work in that picture. Better still is to take a course or learn from experienced Astrologers.