Zodiac or Bha-Chakra (भ-चक्र)

As seen from the Earth, the 9 graha (ग्रह) travel along a belt like path called the Zodiac or the bha chakra (भ - चक्र).

The Sun appears to move in an Elliptic Path that marks the center line of the Zodiac belt.

The zodiac belt has a span of about 8 degrees on either side of this elliptic.



The term zodiac is derived from the Latin word zōdiacus and from the Greek zōdiakos kuklos, that means a "circle of animals".

“Zoon” means "animal" and 6 of the 12 signs of the classical Greek zodiac are represented as animals.
In Vedic Astrology, the term used for Zodiac is bha-chakra. bha = to shine; chakra = wheel.



According to bR^ihat parAshara horA shAstra (BPHS), Chapter III:

शृणु विप्र प्रवक्ष्यामि भग्रहाणां परिस्थितिम्‌।
आकाशे यानि दृश्यन्ते ज्योतिर्बिम्बात्यनेकशः॥ २॥

Listen O Brahmin, I speak of the state of graha that shine;
In the sky there can be seen various luminous bodies.



तेषु नक्षत्रसंज्ञानि ग्रहसंज्ञानि कानिचित्‌।
तानि नक्षत्रनामानि स्थिरस्थानानि यानि चै॥ ३॥

Of these (some) are named the Nakshatras and the others as graha;
Those that are stationery are called Nakshatras.


गच्छन्तो भानि गृह्णन्ति सततं ये तु ते ग्रहः।
भचक्रस्य नगश्व्यंशा अश्विन्यादिसमाह्वयाः॥ ४॥

Those shining (bodies) that move continuously, grasping the Nakshatras, are the Grahas;
The bha-chakra (zodiac) comprises of Ashwini etc. (27) asterisms.


तद्‌द्वादशविभागास्तु तुल्य मेषादिसंज्ञकाः।
प्रसिद्धा राशयः सन्ति ग्रहास्त्वर्कादिसंज्ञकाः॥ ५॥

This (zodiac) divided into 12 parts is correspondingly named as mesha etc.;
(these parts are) known as Rashi; the Graha are named as Sun etc..




Just like a circle, the Zodiac has 360°.

Each Zodiac Sign / rāśi (राशि) thus spans 360/12 = 30°.

The 12 zodiac signs or 12 rāśi (राशि) are:
 

Order	Western Name	Vedic Name
I	Aries	meSha (मेष)
II	Taurus	vR^iSha (वृष)
III	Gemini	mithuna (मिथुन)
IV	Cancer	karka (कर्क)
V	Leo	siMha (सिंह)
VI	Virgo	kanyA (कन्या)
VII	Libra	tulA (तुला)
VIII	Scorpio	vR^iShchika (वृष्चिक)
IX	Sagittarius	dhanu (धनु)
X	Capricorn	makara (मकर)
XI	Aquarius	kumbha (कुम्भ)
XII	Pisces	miina (मीन)

rāśi = heap; and refers to a “heap of stars”.

The groups of stars or Asterisms span the zodiac and are these called nakṣatra (नक्षत्र).


27 nakṣatra (नक्षत्र) span the zodiac hence each nakshatra spans 360/27 = 13°27’

In other words, each rāśi harbors 2 ¼ nakṣatra (नक्षत्र).

The nakṣatra (नक्षत्र) are Fixed Stars. i.e. they appear to be in a fixed position when seen from Earth.


The 9 graha (‘planets’) move through the zodiac belt (grasping the nakshatras) at varying speeds.