Summary: Comparison of the two main types of birth-chart format used in Jyotish
Most Western Astrologers use a circular format birth-chart, but this is not used in Jyotish.
There are two main types of chart formats used in Vedic Astrology – the North Indian and the South Indian system. This often causes confusion to those new to the subject as the charts seem completely different. However, each format is just a different way of representing the same information.
The ‘diamond’ type grid is mainly used in North India and the ‘rectangular grid’ type of chart in South India. Both charts in the diagram below represent exactly the same astrological data. In the North Indian system the ascending sign is always placed in the ‘top diamond’ box and the signs are often numbered 1 to 12, i.e. Aries to Pisces. For the horoscope shown the ascendant is in the 12th sign Pisces, with both Jupiter and Venus in the ascending sign, Rahu in the 4th sign Cancer (corresponding with the 5th house in this chart), etc.
Signs in Jyotish have exactly the same names as those in Western Astrology (e.g. Aries, Taurus, etc.) – but their position in the sky is different from the position of the Western Astrological signs. This is because Vedic Astrology references the signs to the background of the fixed stars in the sky – so it uses the Sidereal Zodiac and not the Tropical one used in the West. Currently there is approximately a 24 degree difference between the two zodiacs (the tropical zodiac uses the spring equinox point as a ‘zero’ reference for the start of Aries and this moves against the background of the fixed stars due to the precession of the equinoxes.)
If we are just beginning the study of Jyotish I believe a slightly modified form of the rectangular South Indian chart format is much easier for Westerners to use.
South Indian Jyotish Birth-chart Format
In the South Indian system each sign always stays in the same box (e.g. Pisces top left).
The sign count is made clockwise around the rectangle (e.g. Aries 1, Taurus 2, Gemini 3 ……. Pisces 12).
The ascendant is shown by a single diagonal line on the chart.
Houses, which correspond exactly with signs in this system, are counted clockwise from the ascendant.
For example, if the ascendant is in Leo then the whole of Leo becomes the first house, the whole of Virgo the second house, the whole of Libra the third, etc.
To help students access and process a lot of information I have added extra compartments to each of the rectangles. This enables us to put in additional, at-a-glance information such as the house number (counting clockwise from the ascending sign), in which house the sign ruler is placed, planetary aspects to the house and what the house number would be if the moon was used as an ascendant: