Career as Astronaut is dream for number of young students. There are a few steps to be Astronaut. You must either enter into reputed IITs or finish your Graduation and Post Graduation in Physics or Instrumentation etc. from a prestigious institute. You should choose Aeronautical engineering or Mathematics or Physics as your future subjects and then you can move further in your aimed direction.
There are huge opportunities for serious candidates in this specialization.
There are also a limited number of institutions that are doing high level research in astronomy. You should try to get your degree under the supervision of a astronomer. Then you will have a reasonable chance of success. At Graduation level, Astronomy courses are not offered by any mainstream universities in India. At the Master's and Ph.D levels, there are several options.
You can choose the institute offering the courses in India from the list given below.
1. Inter-University Centre for Astronomy and Astrophysics, (Pune)
2. Indian Institute of Astrophysics, (Bangalore)
3. Raman Research Institute, (Bangalore)
4. National Centre for Radio Astronomy
5. Indian Institute of Science, (Bangalore)
6. Osmania University, Hyderabad
7. Swami Ramananda Theerth University, Nanded, Maharashtra
8. Tata Institute of Fundamental Research, Mumbai
9. Madurai Kamaraj University, Madurai, Tamilnadu.
10. Radio Astronomy Center, Tamilnadu
11. Mahatma Gandhi University, Kottayam, Kerala.
Admission to these institutions will be based on common entrance test and interview. Candidates must have studies Physics as a main subject in Post Graduation. Some institutes admit engineering students as well. You can visit websites of those institutes for complete details of eligibility and selection procedure.