The Sidereal Zodiac: Why Your Vedic Sign Is Different
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Quick answer: The sidereal zodiac divides the twelve signs by the real positions of the stars. The tropical zodiac used in Western astrology starts Aries at the spring equinox. Because Earth's axis slowly wobbles (precession), the equinox drifts back about 50 arc-seconds a year, and the two zodiacs are now about 24° apart. Most placements move back one sign in a Vedic chart.
What is precession?
Earth's axis traces a slow circle like a spinning top, about once every 26,000 years. So the Sun's position against the stars at the spring equinox shifts a little every year. The two zodiacs lined up roughly two thousand years ago and have drifted apart since.
What is the ayanamsa?
The gap between the two zodiacs is called the ayanamsa. The most widely used value is Lahiri, about 24°12′ in 2026. Subtract it from a tropical position to get the sidereal one. Other values differ by less than a degree or two, which matters only for placements near a sign boundary.
What does it change in my chart?
| Western Sun | Minus 24° | Vedic Sun sign |
|---|---|---|
| Leo 10° | Cancer 16° | Cancer |
| Leo 28° | Leo 4° | Leo |
| Capricorn 5° | Sagittarius 11° | Sagittarius |
Placements in the last six degrees or so of a sign keep their sign; earlier ones move back a sign. The same goes for the Ascendant and the Moon.
Which zodiac is right?
Both, for different purposes. The tropical zodiac follows the seasons; the sidereal zodiac follows the stars. Nakshatras and Dashas are built on the sidereal zodiac, so Jyotish has to use it.
FAQ
How do I find my Vedic sign?
Cast a Vedic chart and it will show you. As a rough guide, subtract about 24° from your Western positions.
Is my Western reading still useful?
Yes. Each system stands on its own. Read Western interpretations with your Western signs and Vedic ones with your Vedic signs, without mixing them.
Which ayanamsa should I use?
Most Vedic astrologers default to Lahiri, and so do we.