Eccentric and Epicyclic Theories in Indian Astronomy

The great Kepler bequethed the Three Laws of Motion to the world and became immortal. That the planets move in elliptical orbits, that a planet moves fastest at perihelion and that the squares of their sidereal periods equal the cube roots of their semi-major axes.

The Hindu astronomers never talked about ellipses. The Indian astronomic books say that the planets go in an epicycle, whose center moves along the mean circular orbit from west to east. This the Epicyclic Theory.

Another theory called the Eccentric Theory says that the planet goes in a circle whose center is not the Earth, but a different point other than the Earth. The distance of this point from the Earth, is said to be equal to the Epicycle's radius. Bhaskara says " The Celestial Sphere's center coincides with the Earth's center. The circle in which a planet goes does not coincide with the Earth's center ". To obtain the true longitudes from the mean, Indian astronomers prescribed bhujaphalam, ( called Equation of Center in the case of Mandaphala, and in the case of the inferior and superior planets, this bhujaphalam also indicates the reduction to geocentric longitudes from the heliocentric ).

From this explanation from Bhaskara, it is clear that the Indian Theory is Heliocentric.