What Is Ayanamsa
Share this post
If you have ever compared a Western horoscope with a Vedic one, you will have noticed that the planets are in different places, often a whole sign apart. The planets have not moved; the two systems start measuring the zodiac from different points. The gap between those two starting points is the ayanamsa.
Two zodiacs
The tropical zodiac starts at the spring equinox, the point where the Sun crosses the celestial equator going north. Wherever that point is, it is called 0° Aries. This zodiac is tied to the seasons and is used in Western astrology.
The sidereal zodiac is fixed to the stars. 0° Aries is a fixed place against the background of the constellations. This is the zodiac of Vedic astrology, and it is why the nakshatras, which are star groups, fit into it so naturally.
Why they drift apart
The Earth's axis wobbles slowly, like a spinning top. Because of this precession of the equinoxes, the equinox point slides backwards against the stars by about 50 seconds of arc a year. That is roughly 1 degree every 72 years, and a full circle in about 25,800 years.
The two zodiacs coincided around 1,700 years ago. Since then the equinox has slipped back by about 24 degrees. That accumulated angle is the ayanamsa (from ayana, movement, and amsa, portion).
Sidereal position = tropical position - ayanamsa
Example
Suppose the Sun is at 10° Aries in the tropical zodiac and the ayanamsa is 24°13'.
- 10° Aries is 10° from the start of the tropical zodiac. Subtracting 24°13' takes us back past 0° Aries into Pisces.
- 30° + 10° - 24°13' = 15°47' Pisces in the sidereal zodiac.
This is why most people's Sun sign in a Vedic chart is the sign before their Western one. Only those born in the last few days of a tropical sign keep the same sign.
Why there is more than one ayanamsa
Everyone agrees on the rate of precession. The disagreement is about exactly where the fixed zodiac begins, because no bright star marks 0° Aries. Different authorities anchor the zodiac in different ways:
| Ayanamsa | Basis | Compared with Lahiri |
|---|---|---|
| Lahiri (Chitrapaksha) | The star Chitra (Spica) at 0° Libra, opposite the start of Aries | About 23°51' in 2000 |
| Krishnamurti (KP) | K. S. Krishnamurti's value, used in the KP system | About 6' less |
| Raman | B. V. Raman's value | About 1°27' less |
| Fagan-Bradley | Used by Western sidereal astrologers | About 53' more |
The figures are approximate, and other values are also in use.
Lahiri is by far the most common. It was adopted by the Indian government's Calendar Reform Committee in the 1950s for the national calendar and panchangs, and it is the default in most Indian astrology software. Unless your astrologer says otherwise, a Vedic chart is almost certainly a Lahiri chart.
When does the choice matter?
For most positions it does not: a planet at 15° of a sign is in the same sign and the same nakshatra under any of the common values. The choice matters at the edges.
Near a sign boundary. With Lahiri, a Lagna might be at 0°40' Leo; with Raman, 1°27' less, it becomes 29°13' Cancer: a different Lagna and a different set of house lords. If you are finding your Lagna and it falls within a degree or two of a boundary, this is worth knowing.
Near a nakshatra or pada boundary. The Moon's star decides the birth star and the first dasha, and the pada decides the navamsa. A Moon within a few minutes of arc of a boundary can change star or pada between Lahiri and KP.
Dasha dates. The Moon's exact position inside its nakshatra fixes the balance of the first Vimshottari dasha, and with it every later date. One minute of arc shifts the dates by about 3 days when the first dasha is the Sun's (6 years) and about 9 days when it is Venus's (20 years). So the 6-minute difference between Lahiri and KP moves all dasha dates by roughly two weeks to two months. The 1°27' difference of Raman moves them by many months or even years.
Divisional charts. Finer divisions change sign every few degrees or less, so they are the first to change when the ayanamsa does.
Practical advice
- Be consistent. Predictive rules and dasha timings should be judged with one ayanamsa. Do not mix a Lagna from one system with dashas from another.
- Know what your software uses. When two programs or two astrologers give slightly different degrees or dasha dates for the same birth details, a different ayanamsa setting is the most common reason.
- Follow the method's own standard. KP rules were developed with the KP ayanamsa; mainstream Parashari practice in India uses Lahiri.
- Test doubtful cases against life events. When a Lagna or birth star is on a boundary, an astrologer compares both possibilities with the person's nature and with dated events, such as education, marriage or a move, to see which chart fits.
- Mind the birth time first. A four-minute error in birth time moves the Lagna by about one degree, far more than the gap between Lahiri and KP. An accurate birth time matters more than the fine choice of ayanamsa.
Summary
Ayanamsa is the slowly growing angle, a little over 24 degrees today, between the season-based tropical zodiac and the star-based sidereal zodiac used in Vedic astrology. Subtract it from a tropical position to get the sidereal one. Lahiri is the Indian standard; KP is about 6 minutes less and Raman about a degree and a half less. The choice changes a chart only near sign, star or pada boundaries and in the exact dasha dates, so pick one standard, know which one your chart uses, and stay with it.
Frequently Asked Questions (FAQ)
What is ayanamsa?
Ayanamsa is the angle between the tropical zodiac, which starts at the spring equinox, and the sidereal zodiac, which is fixed to the stars. Vedic astrology subtracts it from tropical positions to get sidereal positions.
What is the value of the Lahiri ayanamsa?
It was about 23 degrees 51 minutes at the start of the year 2000 and grows by roughly 50 seconds of arc a year, so it is a little over 24 degrees in the mid-2020s.
Which ayanamsa is correct?
There is no universally agreed answer. Lahiri (Chitrapaksha) is the Indian government's standard and the most widely used. KP astrologers use the Krishnamurti value, which is only about 6 minutes of arc less.
Why is my Vedic sign different from my Western sign?
Western astrology uses the tropical zodiac and Vedic astrology the sidereal zodiac. The two are about 24 degrees apart, so most people's Sun sign moves back by one sign in the Vedic chart.
Comments