Ayanamsa is the angular difference between the tropical zodiac (used in Western astrology) and the sidereal zodiac (used in Vedic astrology). Due to the phenomenon called precession of the equinoxes, the Earth's axis wobbles slowly, causing the equinoctial points to shift backward through the zodiac at about 50 arc seconds per year. Ayanamsa compensates for this shift.

Why Does Ayanamsa Matter?

Because of precession, a planet at 20° Aries in the tropical chart sits at approximately 20° minus ~24° = about 26° Pisces in the sidereal chart today. This ~24° difference is the current Ayanamsa. Different schools use slightly different calculations for this value, leading to different planetary placements in the birth chart. Choosing the correct Ayanamsa is therefore critical for accurate predictions.

Lahiri Ayanamsa (Chitrapaksha)

The most widely used system in South India and the official Ayanamsa adopted by the Government of India. It is based on the position of the star Chitra (Spica) at 180° longitude. Most Telugu astrologers and Panchangam publishers follow Lahiri. The Mana Pandit Kundali tool defaults to Lahiri.

Raman and KP Ayanamsa

B.V. Raman's Ayanamsa differs from Lahiri by about 0°22′ — a small but significant difference for precise house calculations. Krishnamurti Paddhati (KP) uses its own Ayanamsa developed by K.S. Krishnamurti which places greater emphasis on the sub-lord system of prediction. KP is popular among astrologers who focus on precise event timing.