What is Ayanamsa, and which one should I choose?
Why Indian charts differ from Western ones by about 24°, and the difference between Lahiri and KP.
Western astrology measures planets from the point where the Sun crosses the equator in spring (the tropical zodiac). Indian astrology measures them against the fixed stars (the sidereal zodiac). Because the Earth's axis slowly wobbles — a motion called precession — these two starting points drift apart by about 50 seconds of arc every year. The gap between them is the ayanamsa.
Today the ayanamsa is a little over 24°. That is why a planet at 10° Taurus in a Western chart sits at about 16° Aries in an Indian one, and why the Sun's sign in a Western chart is usually one sign ahead of the Sun's sign in an Indian chart.
Why there is more than one
Everyone agrees on the drift; astronomers and astrologers differ on the exact year the two zodiacs coincided. Each choice gives a slightly different ayanamsa. AstroRealm offers the two used most in South India:
- Lahiri (Chitrapaksha) — recommended by the Government of India's Calendar Reform Committee (1955) and used in most Indian panchangams and horoscope software.
- Krishnamurti (KP) — used in the Krishnamurti Paddhati (KP) system. It is about 6 arc-minutes smaller than Lahiri.
Does the choice matter?
For most people, no: a 6′ difference rarely changes the rasi, nakshatra or lagna. It matters when the Moon or the lagna sits very close to a boundary, and it matters a great deal in KP astrology, where sub lords span only a fraction of a degree. If you are taking the chart to an astrologer, choose the ayanamsa they use. Every AstroRealm printout states which ayanamsa it used, with its exact value.
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For guidance only. Please consult an astrologer before taking decisions.