Hi,
You can go for B.Sc in Astrology after 12th. It is a 3-year course involving the study of the physical and chemical properties of the celestial bodies and the natural phenomena that occur in the universe. The eligibility for this course is that you must complete your +2 with physics, chemistry, and mathematics.
Top universities offering the course are:
Osmania University, Hyderabad
Andhra University, Vishakhapatnam
Andhra University, College of Science and Technology, Vishakhapatnam
Punjabi University, Punjab

Top recuiting companies of the course are: Planetariums, Universities, Observatories, Laboratories, Defense and Space Research Organizations, Electrical Component Manufacturers, Electronic Equipment Manufacturers.

Average course fee: INR 5k to 5lakhs
Else
You can join any undergraduate programme and do Master's in astrology.

After Master's you can apply for Ph.D in it. For entrance into IIA , you have to give JEST I.e Joint Entrance Screening Test . It is conducted in the month of February.
Highly motivated candidates with a M.Sc. degree in Physics / Maths or M.Tech. in Engineering & exceptional candidates with B.E. /B.Tech. degree and a good background in physics are eligible to apply for admission to the Ph.D. programme.

You can know more about the course through the link: http://www.iiap.res.in/?q=opportunities/career