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Sidereal vs Tropical Zodiac: Understanding Ayanamsa and Celestial Axes

Why Vedic astrology uses the fixed sidereal stars (with Lahiri ayanamsa) while Western systems use seasonal equinoxes.

By NaamSetu Editorial TeamPublished 6 September 20266 min read

The distinction between Vedic (Sidereal) and Western (Tropical) astrology rests on how zero degrees Aries is defined.

Learn more about high-precision calculation algorithms on [NaamSetu Jyotish](https://jyotish.naamsetu.in).

## Precession of Equinoxes and Ayanamsa Due to the Earth's axial precession, the equinoxes drift relative to fixed stars at roughly 50.29 arcseconds per year. The cumulative angular difference is called **Ayanamsa**.

## Lahiri Ayanamsa Standard NaamSetu uses the **Lahiri (Chitrapaksha) Ayanamsa**, which aligns 0° Libra with the star Spica (Chitra). This is the official astronomical standard recognized by the Indian Calendar Reform Committee.

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