Hi Sirisha, 

Most astronormer career choices, would require you to have a Ph.D. So, start with pursuing a bachelors in Physics, Chemistry, Math or Aeronautical Sciences and then go further for a masters or specialiszation in Astronomy. The Inter-University Centre for Astronomy and Astrophysics, Pune, India is one of the best institutes offering Ph.D programs. You can also look for the following univerisites: 

1. Indian Institute of Science, Banglore.

2.The Inter-University Center for Astronomy and Astrophysics, Pune

3. indian Institute of Astrophysics, Banglore

4. Raman Research Institute, Banglore

5. Physical Research Laboratory, Ahmedabad

6.Tata Institute of Fundamental Research, Mumbai

7. The National Center for Radio Astrophysics, Pune 

Read up more about the career choice at Careers360 using the link given here: https://www.careers360.com/question-career-path-to-become-astronomer-nasa

Thanks,