Ayana Bala is identical to Cheshta Bala for the Sun (the Sun has no own Cheshta Bala because he is always in Sama motion).
Mercury plays a special role in so far as it is strong with northern as well as southern declination. So Mercury is again the most neutral planet.
All planets (including Mercury) have medium Ayana Bala near the equinoxes.
The planets form 3 groups, each of them having their own rules for Ayana Bala calculation. All planets have 50% Ayana Bala strength (30 Virupas) in the equinoxes (0 Aries and 0 Libra).
The specific rules are
The rule for Ayana Bala calculation is
where eps is the obliquity of the ecliptic (23:27). The rules for addition/subtraction of the Kranti value are
Find out the tropical longitude of a planet i.e. add Ayanamsa to its longitude. Calculate the distance from the nearest equinoxe. This value must be between 0 and 90. There are 3 Khandas (portions) for 3 possible Rasis: 45 (1st sign), 33 (2nd sign) and 12 (3rd sign).
Example: A planet in 10° Pisces has distance 20° from equinoxe (0° Aries) and will get a value of 20/30 * 45 = 30.
2.) Planets in the 2nd sign (30°-60°) will get the Khanda of 45 plus proportional value (of 33) for their longitude in the 2nd sign.
Example: a planet in 10° Scorpio has distance of 40° from equinoxe. So the value is 45+ 10/30 * 33 = 56.
3.) Planets in the 3rd sign (60° - 90°) get a value of 78 (=45+33) plus the portion of the Khanda value (12).
Example: a planet in 15° Cancer has distance 75° from equinoxe. The total value will be 78 + 15/30 * 12 = 84.
The result must be between 0-90. Planets near the equinoxes get a small value (near 0); planets near 0°Cancer or 0°Capricorn get a high value (near 90).
Same vice versa for Sun, Mars, Jupiter and Venus i.e. 90 must be added for for positions between Aries and Virgo; the value must be deducted from 90 for Libra to Pisces.
For Mercury 90 must always be added.
The result must be divided by 3 to get Ayana Bala in Virupas. The value must be between 0 and 60 Virupas.
The calculation rule is
where len is the tropical longitude of the correponding planet/luminary.
The rules for addition/subtraction are the same as above.
The table shows that the results are quite similar; the tolerance is within 2 Virupas.
|Planet||Length||Declination||Method 1||Method 2||Method 3|
|Sun||10°22 Taurus||14°56 N||49.1||48.8||49.4|
|Moon||29°55 Cancer||21°12 N||4.2||3.9||4.0|
|Mars||07°32 Pisces||10°12 S||17.0||18.8||18.5|
|Mercury||15°05 Taurus||17°36 N||52.5||50.5||51.2|
|Jupiter||06°57 Cancer||23°23 N||59.9||59.1||59.8|
|Venus||26°28 Pisces||02°29 S||26.8||28.2||28.2|
|Saturn||25°20 Capricorn||20°54 S||56.7||56.6||57.1|