There are three main sub-divisions of astrology according to the Vedas. Samhita encompasses the study of the collectivities in the world, namely weather forecasts, natural disasters, cyclones, floods, earthquakes, wars, economic trends, governments, national and international events, and yearly predictions. Siddhanta or Ganita is the mathematical aspect of astrology. There are five important Siddhantas that are important for every astrology to study before beginning to learn astrology: Surya Siddhanta, Paulisha Siddhanta, Romaka Siddhanta, Vasishta Siddhanta and Pitamaha Siddhanta. The third division of astrology is called Hora. This deals with individual horoscopes and electional astrology (Muhurta). Muhurta or auspicious timing is the study of favourable planetary dispositions for accomplishing success in day to day activities. 

 

To put it in other words, genethlialogy is the branch of astrology that deals with making predictions about human lives based on the positions of planets at birth. Mundane astrology deals with groups, communities, countries or all of humanity as a whole. It predicts whether, earthquakes, cultivation of crops or breeding of animals, etc. Horary astrology gives answers to particular queries posed to the astrologer and the answers are based on planetary positions at the moment the question is asked. 

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A horoscope is a pictorial representation of planets and their corresponding positions in the zodiac signs at the time of birth of an individual or event. The casting of a horoscope enables us to predict the likelihood of an occurrence in the life of the event or the individual in question. Since the sky is not flat but is rather a sphere, the planets are calculated based on ecliptic points, that is, the intersection of the plane of the earth’s orbit with the celestial sphere. This is the orbit around which the sun rotates including other planets. The path is approximately 7-8 degrees above the ecliptic. In order to identify the specific position of the planets, the vernal equinox is taken as a reference point, that is, the intersection between the equator and the ecliptic path. On this path are other star groupings which do not alter their relative positions in the sky. These star groups are the zodiac signs starting from Aries to Pisces. They are divided into 30 degrees each. 

In layman's terms, horoscopes are linked to mapping the positions of the celestial bodies during the time an individual was born or when a significant event took place. The information from the chart in relation to the future is of utmost relevance in trying to comprehend the person's life journey. In issuing a horoscope, the first step is gathering the placement of the various components of the sky. The coordinates of planet locations are computed from a spherical region called the celestial sphere. The most critical path on this sphere is the ecliptic, which is the orbit of the Sun, and by extension, the orbit of other planets. This path is the center of the planetary ecliptic which is made up of 7 to 8 degrees above the ecliptic plane.

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For precise positioning, the vernal equinox is taken as the point of reference. This point acting as a "starting point of the universe," is the place where the Earth’s equator meets the ecliptic, and serves as the basis for placing the zodiac signs. The zodiac is 360 degrees around and is split into twelve equal sections each of which depicts one from the twelve signs from Aries to Pisces and each section has a measure of 30 degrees on the celestial sphere.