Friday, May 02, 2014

FAQs regarding Computation of Planetary Longitudes !

Q - What is the Western method ?

A- The Western method is to find out the Mean Anomaly of the planet, then the true Anomaly and the add to it the Argument of Perihelion to get Theta ( Theta = v + w ). The next step is to reduce it to Cartesian coordinates, x, y and z and then the last step is to reduce it to Spherical coordinates, r, theta and phi.

Q - What is the Indian Method ?

A - The Indian method is to reduce the planet first to the Heliocentric Coordinate System, Manda Kriya, then reduce it to the Ecliptic Coordinate System, Parinathi Kriya and then reduce it to the Geocentric Coordinate System. Sheegra Kriya.

Q - If both methods are different, why some say Indians plagiarised from the Greeks ?

A - Such talk is all rot and nonsense.

Q - What are the elements involved in the Western method ?

A - In Western Astronomy, we have six orbital elements

Mean Anomaly, m
Argument of Perihelion, w
Eccentricity, e
Ascending Node, N
Inclination, i, inclinent of orbit
Semi Major Axis, a

Q- The elements involved in the Indian Method ?

A - The Nine Orbital Elements of the Indian School of Astronomy and Maths, from which planetary longitudes are computed.

Mean longitude of Planet, Graha Madhyama , M
Daily Motion of the Mean Longitude, Madhyama Dina Gathi, Md
Aphelion, Mandoccha, Ap
Daily Motion of Aphelion, Mandoccha Dina Gathi, Apd
Ascending Node, Patha, N
Daily Motion of Ascending Node, Patha Dina Gathi, Nd
Heliocentric Distance, Manda Karna, radius vector, mndk
Maximum Latitude, L, Parama Vikshepa
Eccentricity, Chyuthi,e

Q - What about the dates of the astronomers who computed first ?

A - Parameswara - 15th century C E
Nilakanta - 16th
Kepler - 17th
Laplace - 18th

Dear readers, it is clear from this data who computed planetary longitudes first !

More info about Computation of Longitudes at

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