Astrology is part of Jyothisa which include astronomy also. By astronomy we mean to examine the position of planets and other heavenly bodies. It does not concern itself with how they affect the life of the world or the individual. Such functions belong to astrology. During Vedic period, astrology is used to find muhurtha, auspicious time to start an event. The predictive astrology is developed much later

The three skanda or part of jyothisa are: siddhanta, hora and samhita. The siddhanta skandh, deals with arithmatics, trigonometry, geometry and algebra. The design and measurement of Yagnavedi and homakunta is done with help of Siddhantha Skandha. Hora skandha deals with the position of planets and its influence on us. This branch of Jyothisa is predictive in nature. The Samhita skanda of jyothisa deals with right measure of house, presence of water underneath earth, manufacturing of perfume etc. Nimitta and sakuna are also part of it

There are seven grahas, celestial bodies that influence us. They are Sun, Moon and five planets namely, Mars, Mercury, Jupiter, Venus, Saturn. Two more celestial bodies as Rahu and Ketu were also mentioned in Jyothisa sastra. They are chayagrahas or shadow planets. And their orbits are opposite to that of sun and moon. Apart from Navagrahas, Nakshatra, the constellation also influence us