Sayana – Nirayana OR Tropical – Sidereal
Buddhike Sri Harsha Indrasena, Sri Lanka
12th November 2011
It is often heard that Sayana-Nirayana and Tropical-Sidereal terms are being used loosely
and interchangeably. What is the correct terminology?
What is the definition of Tropical and Sidereal?
http://en.wikipedia.org/wiki/Sidereal_and_tropical_astrology defines Sidereal and
Tropical as follows:
Sidereal and tropical are astronomical terms used to describe two different definitions of
a "year". They are also used as terms for two systems of ecliptic coordinates used in
Both divide the ecliptic into a number of "signs" named after constellations, but while the
sidereal system defines the signs based on the fixed stars, the tropical system defines it
based on the position of vernal equinox (i.e. the intersection of the ecliptic with the
While classical tropical astrology is based on the orientation of the Earth relative to the
Sun and planets of the solar system, sidereal astrology deals with the position of the Earth
relative to both of these as well as the stars of the celestial sphere. The actual positions of
certain fixed stars as well as their constellations are an additional consideration in the
What is the meaning of Sayana and Nirayana?
1) Sayana means ‘with Ayana (Ayanamsha)’,
2) Nirayana means ‘with out Ayana (Ayanamsha)’.
Sayana and Nirayana are relative terms. Why are these terms relative?
If longitudes are calculated according to Tropical astrology, it is necessary to subtract
Ayanamsha to get Sidereal Longitudes. So the figures are obtained only after using
Ayanamsha. The converse is also true. If planetary longitudes are calculated according to
Sidereal system (say Surya Siddhantha longitudes) and if Tropical longitudes are wanted,
then it is necessary to add again Ayanamsha.
Therefore Sidereal astrologers may call Tropical longitudes as ‘Sayana’ if they obtain
Tropical longitudes by adding Ayanamsha to Sidereal longitudes. Sidereal longitudes of
sidereal astrologer are, therefore, ‘Nirayana’.
In the same way Tropicalists who calculate planetary longitudes using Tropical methods
are ‘Nirayana’. For the tropicalist, Sidereal longitudes are ‘Sayana’ because the
tropicalist has to subtract Ayanamsha or Ayana from Tropical figures to get Sidereal
Sayana-Nirayana OR Tropical-Sidereal
Therefore considering the meanings of the words Sayana and Nirayana
1) For the Tropicalist, Sidereal astrology is Sayana and Tropical astrology is Nirayana.
2) For the Siderealist, Tropical astrology is Sayana and Sidereal astrology is Nirayana.
Do siderealists use Tropical longitudes?
The answer is yes.
Sidereal astrologers do use Tropical longitudes once in a while in Horoscope reading.
One example is calculation of Ascendant according to Panchanga method. Traditional
Hindu astrology is based on the sidereal or visible zodiac, accounting for the shift of the
equinoxes by a correction called Ayanamsha. Therefore in practice when it is called
Sayana it refers to Tropical astrology. Nirayana refers to Sidereal astrology. Even in
Greece before Ptolemy Sidereal Zodiac was in use, and that was the practice in
Was Sidereal astrology in use in ancient Greece?
Naming of the Zodiac according to solar seasons, or Tropical Zodiac, was introduced by
Ptolemy (2nd century AD) following the discovery of Precession of Equinoxes by
Hipparchus (ca. 130 BC). But before Ptolemy, even in Greece the Zodiac was named in
“But earlier Greek astronomers like Eudoxus spoke of vernal equinox at 15° in Aries,
while later Greeks spoke of vernal equinox at 8° and then 0° in Aries (cf. p. 16, S. Jim
Tester in ref.), which suggests use of sidereal zodiac in Greece before Ptolemy and
Hipparchus.” (Source: http://en.wikipedia.org/wiki/Sidereal_and_tropical_astrology)
Do stars move?
Stars hardly move if at all. For practical purposes stars do not move.
Fixed stars are Sidereal. Tropical positions of stars are obtained by adding Ayanamsha to
sidereal position of stars. Since Solar seasons shift along the back ground of belt of fixed
stars, Ayanamsha increases at a rate of 1.4 arc degrees per century. Therefore stars appear
to be moving according to Tropical astrology. This is rather a theoretical phenomenon
than the truth.
The positions of stars are invariably fixed. Otherwise it is not possible to measure
Precession of Equinoxes. It is possible to calculate Equinoxes even if the stars move but
not Precession. Precession is calculated in relation to a background of fixed stars.
Synodic Lunar month is neither Sidereal nor Tropical
Sidereal system defines the signs based on the fixed stars, the tropical system defines it
based on the position of vernal equinox.
Synodic month is based on Lunar Tithis. Tithis are calculated in relation to Sun. Tithis
are not related to either stars (Sun is not a Star in astrology!!!!!!!!) or Vernal Equinox. So
by definition Tithis are neither Tropical (Sayana) nor Sidereal (Nirayana).
BUT, since Lunar months are named according to Sidereal Solar months, it is not wrong
altogether to say that Lunar months are Sidereal.
It is good idea not to use words Sayana and Nirayana any longer because these are
relative terms. The correct terms are Tropical and Sidereal.