What is ayanamsha in astrology

Ayanamsha is a term you cannot avoid in sidereal astrology, yet it is rarely explained in simple words. Let's look at what it is, why it is needed, and which scale to choose.

What is ayanamsha in simple words

Ayanamsha is the difference, in degrees, between the beginning of the tropical and the sidereal zodiac. The word comes from Sanskrit and translates as "part of the path" (ayana + amsha).

In practice it solves a simple problem: if you know your Western (tropical) sign and want to find out your Vedic (sidereal) sign, you subtract the value of ayanamsha. With an ayanamsha of 24°, tropical Aries becomes sidereal Pisces.

Why it is needed

The sidereal zodiac is tied to the stars, the tropical one to the seasons. Because of the precession of the Earth's axis, their origins drift apart. Ayanamsha quantifies this drift as of a specific date. Without it, it is impossible to:

• calculate the sidereal position of planets;
• build a Vedic natal chart;
• compare Western and Indian horoscopes.

What kinds of ayanamsha exist

The value of ayanamsha depends on which star the reference point is tied to. This is where the many scales come from:

lunar.day offers more than forty ayanamshas, from historical to modern ones, and each of them affects which sign the Moon will fall into.

How ayanamsha affects the lunar calendar

In the lunar calendar's sidereal mode, it is ayanamsha that determines the Moon's position among the signs. Switch the scale from Fagan-Bradley to Lahiri, and the Moon's sign shifts by several degrees — important for precise practices.

Summary

Ayanamsha is the angle of the offset between the tropical and sidereal zodiac, currently about 24°. It converts seasonal signs into stellar ones and lies at the base of the entire Vedic calculations. The choice of scale depends on the tradition; by default lunar.day uses Fagan-Bradley, and it can be changed with a single click.

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See also: types of zodiac systems, tropical versus the sidereal.