Kundali Basics5 min read · Updated 2026-06
Why is your Vedic sign often one back from your Western sign? The answer is the ayanamsa — the gap between the sidereal and tropical zodiacs.
Western astrology uses the tropical zodiac, which fixes 0° Aries to the spring equinox. Vedic astrology uses the sidereal zodiac, which measures signs against the fixed background stars. Because the Earth's axis slowly wobbles — a motion called the precession of the equinoxes — the two systems have drifted apart over the centuries.
Today the gap is roughly 24°, which is why many people find their Vedic Sun sign is the one before their Western Sun sign. Someone who is a late Leo in Western astrology may well be a Cancer in Vedic terms.
The exact size of the gap is called the ayanamsa, and it increases by about 50 arc-seconds a year. The most widely used value in Jyotish is the Lahiri (Chitrapaksha) ayanamsa, adopted as a standard in India, though other ayanamsas such as Raman and KP exist.
When a Vedic chart is cast, the software subtracts the ayanamsa from the tropical positions to obtain sidereal longitudes. This single adjustment is the main calculational difference between a Western and a Vedic chart.
Neither system is simply right or wrong; they answer different questions and rest on different philosophies. The sidereal approach ties the signs to the actual constellations and underpins the nakshatra system and dasha timing that give Jyotish much of its predictive power.
If you read both Western and Vedic interpretations, expect the sign placements to differ. Judge each system by its own tradition rather than expecting them to match.
The sidereal zodiac used in Jyotish is offset from the tropical zodiac by the ayanamsa, currently about 24°, which often shifts the Sun back by one sign.
It is the most widely used sidereal correction value in Vedic astrology, named after astronomer N. C. Lahiri and adopted as an Indian standard.
Yes, it increases by roughly 50 arc-seconds per year due to the precession of the equinoxes.
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