Tag Archives: ayanamsha

Ayanamsha Principles

Summary: Covering the basic principles and applications of the Ayanamsa (Ayanamsha) which is used to translate planetary positions from the Tropical zodiac into the Sidereal zodiac.

Quick Facts about the Ayanamsha

    • The Tropical Zodiac moves slowly relative to the background of the ‘fixed’ stars [1] and the Sidereal Zodiac does not move at all. So it, and all the signs in it, remain anchored forever against these stars.
    • The Ayanamsha is the angular distance between the starting point of the Tropical zodiac and the starting point of the Sidereal zodiac. Currently it is around 24 degrees.
    • Sidereal Position = Tropical Position – Ayanamsha
    • For example: if the Sun is at 29 degrees Virgo in the Tropical zodiac it will now be located at 29 – 24 deg. = 5 deg. Virgo in the Sidereal zodiac. However, if it lies between 0 deg. and 24 deg. in Virgo in the Tropical zodiac it will now be in Leo in the Sidereal zodiac. It has moved ‘backwards’ by the Ayanamsha amount. Suppose the Sun was at 20 degrees Tropical. This is equal to Sun at 20 – 24 = – 4 degrees from Virgo sidereal. This means it has moved backwards into the sign before it, so is now at 30 – 4 = 26 degrees Leo.
    • The Ayanamsha is important. It enables the position of the planets (as calculated by astronomers) to be accurately placed in their correct signs, houses and Nakshatras in the Sidereal chart. This forms the foundation for accurate predictions.
    • The Ayanamsha used by most professional Vedic astrologers is that calculated by Lahiri (although some astrologers use a small correction factor to ‘fine-tune’ it).
    • Lahiri’s Ayanamsha is also officially recognised by the Indian Government. They have standardised on this Ayanamsha because many (but not all) religious festivals in India are based on the Moon (sometimes both Sun and Moon), its phases and position in the Nakshatras or lunar mansion
    • Because of the astronomical phenomenon known as the ‘precession of the equinoxes’ the Ayanamsha is not a fixed number, but increases slowly with time.
    • If we take Lahiri’s Ayanamsha we find it was about 23 degrees in 1950 (the year I was born) and is now about 24 degrees. So it increases by an average of about 1 deg. every 72 years.
    • At some time in the distant past the two zodiacs were in perfect alignment and coincided exactly . Both then had the same starting point in the sky – estimated to be around 285 AD (if using the Lahiri Ayanamsha).
    • If we are just beginning our studies of Jyotish it is highly recommended we start with Lahiri’s Ayanamsha. This is usually an option (often default) in Vedic astrological software. Lahiri’s Ayanamsha is published in most ephemeris (ephemerides) tables. After we gain more experience we can explore the consequences and results of different Ayanamshas.

Ayanamsa (Ayanamsha) – Basic Principles

The Ayanamsa (pronounced ‘Ayanamsha’) is the angular distance, measured in degrees, between the starting point of the Tropical zodiac (used by most western astrologers) and the starting point of the Sidereal zodiac used by all Vedic astrologers.

So, what is the difference between the two zodiacs? Well, both the Tropical and the Sidereal zodiacs are identical in that both have 12 signs and each sign occupies exactly 30 degrees of the sky (or ‘celestial sphere’). Both also have identical names for the signs e.g. Aries, Taurus, Gemini, etc. The only difference between them is where they start in the sky and this difference is called the ‘Ayanamsha’.

The starting point of the Tropical zodiac (astrologers call this ‘zero degrees Aries’) can be measured with very high precision by astronomers and this precise point in the sky then referenced to the very distant ‘fixed’ stars [1] in our own galaxy. This measurement of the Spring (sometimes called ‘Vernal’) Equinox defines the position of zero degrees Aries in the sky. So, the Tropical zodiac is linked to the seasons. Also the signs of this zodiac slowly move through the sky. They don’t stay in the same place when referenced to the distant stars.

The starting point of the Sidereal zodiac cannot be measured directly, but its position can be inferred. It can also be found by ‘reverse engineering’ – by examining real life events matched against birth-chart predictions. Various scholars and academics have arrived at their own figures for the angular distance between the starting points of the Tropical and Sidereal zodiac. Most accepted Ayanamshas are within one or two degrees of each other [3]. Although this doesn’t sound much, it can have a major influence on chart interpretation and predictions if a planet’s position ‘moves’ between signs or houses as a result of different Ayanamshas. It also seriously affects the divisional charts (e.g. ninth divisional chart or ‘Navamsha’ – which is examined for details about marriage and partnerships) used in Jyotish. It can also affect the interpretation of transits too!

The Tropical Zodiac moves against the background stars

If the Spring equinox point always remained in the same location (with reference to the ‘fixed’ background stars) the Ayanamsha concept would be fairly straightforward.

Unfortunately things get more complicated as the starting point of the Tropical zodiac actually moves relative to the background of the ‘fixed’ stars over a period of time. This movement, although small (e.g. an average of about 1 degree per 72 years), is caused by the astronomically observable ‘precession of the equinox’ phenomenon [2].

To further complicate things, the rate of movement of the equinox point itself varies over a period of time. This is due to complex gravitational interactions between the Earth, Sun, Moon, Jupiter, etc. in our solar system. So the figure of 1 degree per 72 years is just an average. Complex astronomical algorithms can compute a more accurate figure over long periods of time.

Footnotes

[1] The ‘fixed stars’ are so far away from earth that their angular motion relative to our sun is extremely small, even over many thousands of years. So we can legitimately use the term ‘fixed’ or ‘immovable’.

[2] The equinox point on the Earth’s orbit around the sun moves, relative to the background of the ‘fixed’ stars, due to what is called the ‘precession of the equinox’. This is a well-defined astronomical phenomenon which is due to a slight ‘wobble’ on the Earth’s axis of spin.  The wobble is caused by gravitational forces from Sun and Moon that act on the bulge at the equator (as the rotating earth is not a perfect sphere due to ‘centrifugal’ forces) . It is a bit like a child’s spinning top or toy gyroscope that wobbles – the top spins rapidly about the central axis of spin, but the axis itself slowly rotates and  traces out a conical shape. The Earth takes around 26,000 years to complete 1 precessional cycle (calculated using present rate of precession).

[3] Ayanamshas Compared. The following, frequently quoted  figures were calculated by an online Ayanamsha tool  for the 1st January 2024:

Raman Ayananmsha: 22 deg 44 mins

KP Ayanamsha: 24 deg 06 mins

Lahiri Ayanamsha: 24 deg 11 mins

Fagan-Bradley Ayanamsha:  25 deg 04 mins

Note the very close agreement between the Lahiri calculation and that of KP (Krishnamurti Paddhati system). The Fagan-Bradley figure is not used by Jyotish Astrologers, as it was intended for Western  Astrologers using the Sidereal Zodiac.


Additional Information on Vedic Astrology

Introduction to Jyotish. A range of articles for people entirely new to Vedic Astrology. Including: Introduction, FAQs, Origins and Karmic Implications.

Key Concepts in Jyotish. Articles covering the Sidereal Zodiac, Planetary Forces, Forecasting Analogies and ‘Planetary Antidotes’.

For Western Astrologers. Articles examining major differences between the two systems and the paradigm shift needed by Western Astrologers wanting to understand the subject.

Learn Jyotish. An extensive collection of articles covering key facts, concepts and methods. Aimed at ‘foundation level’ students. Includes essential information needed before beginning chart interpretations. Covering: Chart Formats, Planets, Houses, Mahadasha Periods, Transits, Aspects, Birth-time Errors, Natural and Functional Benefics / Malefics, Chart Interpretation Basics, etc.

Jyotish – Sidereal Zodiac

Summary: This article examines the differences in the zodiacs use by Vedic Astrology and Western Astrology.  It explains why Jyotish uses the fixed sidereal zodiac and not the movable tropical zodiac. It shows how sun signs, ascendants and all planetary positions can appear in different signs in the two systems.

Jyotish uses the Fixed Sidereal Zodiac

    • Jyotish astrology uses a different zodiac from that used in western astrology
    • The zodiacs used in both Jyotish and Western Astrology are based on an imaginary sphere in the heavens. In both systems this is divided into 12 equal parts, each of 30 degrees, just like the segments in an orange. Both zodiacs use the same sign names e.g. Aries, Taurus, etc. for each of the segments. The sun takes about one month to apparently ‘move’ through each zodiac sign.
    • Jyotish uses the fixed or sidereal zodiac. ‘Sidereal’ means ‘with respect to the stars’. So the starting point of the sidereal zodiac is permanently fixed in one position using the background of non-moving stars in our own galaxy as a reference point [1]. So, in the sidereal zodiac, the sign divisions remain forever fixed against the background of the stellar constellations. Therefore the starting point of the first sign (called ‘Aries’) is always fixed in Vedic Astrology. This means all the other signs of the zodiac are also permanently fixed relative to the distant background stars.
    • Western Astrology uses the movable, tropical zodiac. The starting point of this zodiac actually moves relative to the background of the ‘fixed’ stars over a period of time according to the position of the equinox. This movement is caused by the astronomically observable ‘precession of the equinox’ phenomenon [2].
    • So, in Western astrology the position of what is known as the sign of ‘Aries’ actually moves through the sky against the background of the fixed stars. It is not linked to a particular stellar constellation at all! Many people, including students of Western Astrology, find this fact very, very surprising.
    • Astronomers often criticise Western astrologers for using the movable tropical zodiac as the sign ‘Aries’ actually moves through the sky over a period of time. However, this objection cannot be levelled against Jyotish astrology as it uses a fixed and not a movable zodiac.

Ayanamsa – Angular Difference Between the Two Zodiacs

    • The angular difference between the two zodiacs is known as the ‘ayanamsa’ and this figure increases with time [3]. Although the starting point of both zodiacs coincided roughly 1700 years ago, the Western astrologer’s tropical zodiac has now moved away from this position.
    • At this point in time (2021) there is a difference of about 24 degrees between the two zodiacs. Therefore, if our Sun is at 29 degrees Virgo in the Western tropical zodiac it will now be located at 29 – 24 deg. = 5 deg. Virgo in the sidereal zodiac. Notice, still in Virgo in this case in both Jyotish and Western astrology.  However, if our sun lies between 0 deg. and 24 deg. in Virgo in the Western tropical zodiac it will now be in Leo in the sidereal zodiac used in Vedic astrology. It has moved backwards in the Vedic chart by the ayanamsa amount (about 24 degrees) and ends up in the previous sign [4]. So, in this case our ‘sun sign’ will now be different: Virgo in Western astrology, Leo in Jyotish! The same principle applies to all other planetary positions in our chart and to our ascendant too. This difference in astrological sign can explain many anomalies in charts interpreted by modern Western astrologers.

Nakshatras – ‘Stellar Constellations’

    • Jyotish regards the ‘stellar constellations’ or Nakshatras as being of considerable importance in chart interpretation, compatibility analysis and in determining the best time for important actions (Muhurtha).
    • There are 27 Nakshatras (sometimes known as ‘Lunar Mansions’) equally distributed throughout the sky (technically: ‘distributed as equal sectors along the ecliptic’).
    •  It is therefore hardly surprising that Jyotish uses a zodiac which is permanently anchored relative to the fixed stars and also to the Nakshatras.

Footnotes

[1] The ‘fixed stars’ are so far away from earth that their angular motion relative to our sun is extremely small, even over many thousands of years. So we can legitimately use the term ‘fixed’ or ‘immovable’.

[2] The equinox point on the Earth’s orbit around the sun moves, relative to the background of the ‘fixed’ stars, due to what is called the ‘precession of the equinox’. This is a well-defined astronomical phenomenon which is due to a slight ‘wobble’ on the Earth’s axis of spin (a bit like a spinning top whose axis itself slowly moves, tracing out a conical shape). It takes around 26,000 years for the earth to complete one precessional cycle.

[3] As of 2021 the angular difference between the two zodiacs is now about 24 degrees. This figure (or one very close to it), derived by Lahiri, is accepted by Jyotish astrologers. Most astrological tables show Lahiri’s ayanamsa. The tropical zodiac, therefore, moves  relative to the sidereal (fixed) zodiac by about one degree every 71 years. (Although this movement seems small it was observed by ancient Egyptian astronomers thousands of years ago – Wow.) Over time it makes a big difference!

[4] The difference in planetary positions between the zodiacs is now around 24 degrees. If our sun was, say 14 degrees in Virgo in Western Astrology, it will be at 14 – 24 = – 10 degrees Virgo in the Vedic system! So it will be 10 degrees before the start (or zero position) of Virgo. This simply means it has has moved backwards and changed sign into the position of 20 degrees in Leo in the Vedic system (as -10 + 30 = 20). However if our sun was at 28 degrees Virgo in the Tropical zodiacit will now be at 28 – 24 = 4 degrees Virgo in the sidereal zodiac. It has still moved backwards, but in this case it has not changed sign


Additional Information on Vedic Astrology

A useful diagram of the Nakshatra placement in the Sidereal Zodiac (use ‘Lunar Constellations’ dropdown) from the Maharishi Jyotish website.

Introduction to Jyotish. A range of articles for people entirely new to Vedic Astrology. Including: Introduction, FAQs, Origins and Karmic Implications.

Key Concepts in Jyotish. Articles covering the Sidereal Zodiac, Planetary Forces, Forecasting Analogies and ‘Planetary Antidotes’.

For Western Astrologers. Articles examining major differences between the two systems and the paradigm shift needed by Western Astrologers wanting to understand the subject.

Learn Jyotish. An extensive collection of articles covering key facts, concepts and methods. Aimed at ‘foundation level’ students. Includes essential information needed before beginning chart interpretations. Covering: Chart Formats, Planets, Houses, Mahadasha Periods, Transits, Aspects, Birth-time Errors, Natural and Functional Benefics / Malefics, Chart Interpretation Basics, etc.