**Eccentric
and Epicyclic Theories of Eternal Astronomy, Sanatana Jyothis Saastra **

**By Govind
Kumar**

**All
planets traverse in ellipses and epicycles and this came to be known as the
Epicycles Theory.
In
the above diagram, the circle A is the mean orbit of the planet. P is the mean
Position of the planet and the small circle P is the epicycle.
The
small epicycles traversed by a planet are calculated and the **

**The
declination of the Sun is computed by the formula
Sin
J = Sin L Sin w
where
J is the Sun's declination of that particular date and time, L is the tropical
longitude of the Sun and w, the Sun's maximum declination, which is 23 degrees
and 27 minutes.
The
Sun's maximum declination will be reached during Karkyadi ( The First Point of
Cancer ) and Makaradi ( The First Point of Capricorn ). At Karkyadi, it will be
+23 d 23 m and at Makaradi, it will be -23 d 27 minutes.
**

** **

**And
at Meshadi ( The First Point of Aries ) and Thuladi ( The First Point of Libra
), the solar declination will be zero. Days and nights will be of equal duration
and hence they are called Equinoxes.
**

** **

**We
have said in our columns that the Indian astronomers said that the planets
revolve around a point different from that of the Earth and Indian Astronomy is
heliocentric.
**

The
above diagram depicts the Eccentric Theory and Reduction of the longitude of the
planet to the heliocentric coordinate system ( known as *Manda Kriya* ).

In
the above diagram

The
angle NAP = *Manda Kendra* or Mean Anomaly

The
Circle A is the mean orbit of the planet

The
Circle B is the true orbit

The
mean planet moves on the mean orbit, known as the deferent.

When
the planet is at N in the mean orbit, he is at M in the eccentric and this is
called*Mandoccha* ( Aphelion ).

When
the planet is at R in the mean, he is at S in the eccentric.

M
and S correspond to Apogee and Perigee in the case of *Manda Phala* correction
( otherwise known as the Equation of Center ).

When
the planet is at M in the eccentric, the position of the true planet coincides
with N, the mean planet and so the *Manda Phala* correction is
Zero.The Equation of Centre at both perigee and apogee becomes zero.

When
the Mean Anomaly lies between 0 and 180 degrees, the Equation of Center is
negative and this is known in Vedic Astronomy as *Meshadi Rinam*,* Rinam* meaning
minus. And when it is between 180 and 360, it is additive and it is known in
Indian Astronomy as *Thuladi Dhanam*, *dhanam* meaning
additive.

Anomaly
has been defined in Western Astronomy as the angle between position and
perihelion. Manda Kendra here is the angle between Position and Aphelion,
aphelion being mandoccha. The term manda explains that planets move slower at
Aphelion !