Astronomy

B.Sc in Astrophysics is a 3 year Undergraduate course. And, to get admission in this course you need to pass in higher secondary school certificate exam from any recognized board and you must have physics and mathematics in your class 12th examination. You have to score minimum 50% marks in your class 12th examination. The eligibility criteria vary from colleges to colleges:
1 Tata Institute of Fundamental Research, Pune
2 Indian Institute of Astrophysics, Bangalore
3 Birla Institute of Technology & Sciences, Pilani
4 Punjab University
5 Indian Institute of Science, Bangalore
6 Raman Research Institute, Bangalore
7 Inter-University Centre for Astronomy and Astrophysics, Pune
8 National Centre for Radio Astronomy
9 Osmania University, Hyderabad
10 Andhra University
11 Institute of Fundamental Research, Tamil Nadu

Hello,
So, you are confused between if you can go to the ISRO or any space science after BCA, then let me clarify you that you cannot go just after BCA. The reasons are following:
(1) Indian Space Research Organization is the only organization in India which conducts all its space program. To enter in ISRO, you must have at least M.Tech in Computer Science or Information Technology. ISRO does not hire the candidates who are only graduates. And if they do then it's a very rare case. So, no chance to get admission there.
(2) ISRO wants the candidates who are specialized with the branches like Aerospace, Aeronautics, Astronautics, Electronics, computer science & IT, Remote sensing & Navigation, Communication, etc. In BCA, you will just get the basic knowledge of Computer Application, BCA is not the stream of core specialization in computer science. So, no chance to go there.
(3) Although, in Space Science Organization, there are huge vacancies for computer science and IT students. But don't ever think to go there with only your graduation degree and no work experience. They do have a ton of weightage on your work experience in a particular field. Through BC, if you can't handle their ultra complex software and programming features. You cannot encrypt the data as they want. So, there are a lot of things which you cannot do with just BCA.
So, I suggest you to do MCA after that from one of the premier institutions and have a lot of experience in any space science or related field. This might help you go get admission in ISRO.
Kindly upvote the answer if you feel satisfied.
Ask any query at any time.
Good luck.

Hi Vani,
It's good that you have a keen interest in Astronomy and Astrophysics. Let me tell you the list of colleges which are the best in India. According to that, you can choose. Here are the list of colleges:
Following are the best institutes for studying Astrophysics:
1. Aryabhatta Research Institute of Observational Sciences (A.R.I.E.S.), Nainital
2. Cochin University of Science and Technology: Department of Atmospheric Sciences, Kochi (Kerala)
3. Harish Chandra Research Institute, Allahabad
4. Indian Institute of Astrophysics, Bangalore
5. Inter University Centre for Astronomy and Astrophysics (I.U.C.A.A.), Pune
6. National Centre for Radio Astrophysics (N.C.R.A.), Pune (Maharashtra)
7. Tata Institute of Fundamental Research, Pune University Campus,
8. Osmania University: College of Science, Hyderabad (Andhra Pradesh)
9. Physical Research Laboratory (P.R.L.), Ahmedabad (Gujarat)
10. Raman Research Institute, Bangalore (Karnataka)
I'll help you out.
Alll the best.

Required Education
Space science is a demanding field of study; depending on the career desired, it requires motivation for years of college and post-baccalaureate study. Degree options include Bachelor of Science in Space Science, Bachelor of Science in Earth and Space Science, or a master's degree or doctorate in atmospheric and space science. Those looking to teach space science can get a Bachelor's, master's, or doctoral degree in education and space science. Students in technical or education programs can expect classes in physics, mathematics, astronomy, and other similar courses; Bachelor's degree programs typically last more than four years due to laboratory requirements.