Parinathi Kriya, Reduction to Ecliptic !

We have said before that the mean longitude of the planet should be subject to a trignometric correction to get the Vikshepa Vritteeya Sphuta or Reduction to Aphelion. Then it is reduced to Ecliptic by the formula

Sin h = 1 - Cos l Sin Y Cos Y / Cos l

The longitude thus obtained is subjected to another trig correction, Reduction to Perihelion or Sheegra Kriya. The term Trignomety, it must be mentioned, is derived from the Sanskrit Trikonamithi and Geometry, from Jyamithi. Brahma Gupta in his mathematical treatise Brahma Sphuta Siddhanta defined Jya as 5 degrees of 1/6 th of a Zodiacal Sign. Bhujamsa, he said, is radius multiplied by modern sine. In hoary times, Astronomy was sister to Astrology and both were united by Mathematics. Astronomy and Maths ( Ganitha ) is one the Three Skandas ( branches ) which constitue Jyothisha or Astro Physics. Samhita ( Philosophy ) and Hora ( Astrology ) were the other branches.