What is Lahiri Ayanamsha? Sidereal vs Tropical in Vedic Astrology
Why Indian astrology uses the sidereal zodiac, what the ayanamsha correction is, and how Chitra Paksha (Lahiri) is computed.
The problem the ayanamsha solves
The Sun does not return to the same fixed star on the same tropical date. Over centuries, the equinox drifts against the backdrop of the nakshatras — roughly 50.3 arc-seconds per year. Tropical (Western) astrology ignores this drift; sidereal (Vedic) astrology subtracts it. The correction angle is the ayanamsha.
Why Lahiri / Chitra Paksha?
Chitra Paksha sets the ayanamsha so the bright star Spica (Chitra) sits exactly at 0° of Tula rashi — a standard recommended by Indian astronomical treatises and used by most panchangas. Lahiri's value is a smooth polynomial fit that stays within about ±0.01° of the classical value across 1900–2100.
What it changes in your chart
Because the ayanamsha in 2026 is about 24.2°, roughly 80% of charts have every planet shift by at least one nakshatra compared with a tropical calculation — and nearly half change Lagna. That is why the same birth data can produce "different" charts on different sites; the difference is almost always the ayanamsha, not the maths.