The Science of Astrology is concerned with the observations of the positions of certain bodies and certain points in the heavens in relation to the earth and with the correspondences between these relative positions and the events which occur on the Earth. That such correspondences do exist is unquestionable. Modern scientific experiments and observation could easily verify this and confirm the findings of the ancient scientists. It does not necessarily follow that the planets and the stars themselves affect or cause such events. It is sufficient to note that certain positions or groupings of the stars or planets in relation to the earth actually do correspond to certain types of events which occur on the earth.
To make the necessary observations and to translate these observations into terms of correspondence with events occurring on the Earth, both physical and psychological, Hindu Astrologers evolved a rational procedure which is based on five main factors: 1. The Zodiac fixed background to which all heavenly bodies are referred. This background is divided into twelve equal parts. (See Figure I). 2. The Asterisms-Subdivisions of the Fixed Background or Zodiac into smaller sections marked by the Fixed Stars. (See Figure 2.) 3. The Solar System-The Sun, the Moon and the planets which, like the Earth, comprise our own Solar system. The motions of these bodies from point to point within the Fixed Background and in relation to the Earth. 4. The Houses-Imaginary space divisions, radiating out vertically from any particular point on the Earth's surface, and marking out divisions of space, traversed by this point during each twenty-four hours, as the Earth revolves on its own axis. 5. Time-Any given moment at which an event occurs.
In order to determine these positions and groupings accurately, Astrologers use a fixed background or plane of reference called the Zodiac.The Zodiacal Circle is in the same plane as the Ecliptic which is the approximate path of the Earth and Planets in their motion around the Sun. The Zodiac, therefore, is merely the Ecliptic extended limitlessly into space.
These twelve equal sections or divisions of the Zodiac are called the Signs of the Zodiac and are named and numbered as follows:
1. Aries 2. Taurus 3. Gemini 4. Cancer 5. Leo 6. Virgo 7. Libra 8. Scorpio 9. Sagittarius 10. Capricorn 11. Aquarius 12. Pisces
Vedic Terminology :
1. Mesha 2. Vrishabha 3. Mithuna 4. Karka 5. Sinha 6. Kanya 7. Tula 8. Vrischika 9. Dhanu 10. Makara 11. Kumbha 12. Mina
It was observed by the ancient Astronomers that many changes occurred within the 30 degree zones mapped out by the Zodiac. It was therefore, found necessary to subdivide each of the twelve sections or Signs of the Zodiac. Using the belt of Fixed Stars which encircle the Earth at the Equator as markers, they divided the Zodiacal Background into 27 sections, the boundary of each being marked by a particular Fixed Star, located close to the Zodiacal belt. These sections are known as the Asterisms or Nakshatras.
They begin at the same point in the Constellation Aries which marks the beginning of the Zodiac,. and since each extends over an arc of 13 deg-20', there are therefore twenty-seven of them in the complete circle of 360 degrees.
The Zodiac and the Asterisms form the fixed background to which all the variables or moving points used in Astrology are referred. A sort of backdrop, in front of which the drama of our solar system is played.