Jyotish Term
Ayanamsa — अयनांश
Short answer. Ayanamsa is the angular difference between the sidereal zodiac (used in Vedic astrology) and the tropical zodiac (used in Western astrology). It is currently about 24° and grows roughly 50 arc-seconds per year due to precession of the equinoxes.
The Earth's rotational axis wobbles slowly over a 26,000-year cycle (the precession of the equinoxes), which causes the position of the vernal equinox to drift backwards through the constellations. The tropical zodiac (Western astrology) ignores this drift and re-anchors itself to the equinox each year. The sidereal zodiac (Vedic astrology) tracks the actual fixed stars and accounts for the drift via an ayanamsa correction. Several ayanamsa variants exist — Raman, Krishnamurti, Fagan-Bradley — but the most widely used in modern Vedic astrology is the Lahiri Ayanamsa, adopted as the official Indian standard by the Calendar Reform Committee in 1955 and used by Swiss Ephemeris under the constant SE_SIDM_LAHIRI. This is also the ayanamsa Zavora uses. The practical consequence: a planet at 5° Aries in tropical astrology is at approximately 11° Pisces in sidereal Vedic astrology in 2026.
Related terms
- Rashi — Rashi is the Vedic term for a zodiac sign — one of twelve 30° divisions of the sidereal zodiac. Each rashi has a ruling planet, an element, and a quality that shapes how planets in that sign behave.
- Kundli — A kundli is a Vedic birth chart — a diagram showing the position of the nine grahas (planets) in the twelve bhavas (houses) at the exact moment of birth. It is the foundation of all Jyotish prediction.
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