Astronomy

Hi
TIFR is an autonomous Research Institute under the Department of Atomic Energy, Government of India. It is also a Deemed University recognized by the University Grants Commission, offering Ph.D, Integrated M.Sc.-Ph.D, and M.Sc programs in physics, chemistry, biology, mathematics, computer science and science education. So for your B.Sc, you may apply to IISC through JEE.

Hi
The best institute for PhD in astrophysics is IIA which provides joint work with IISC. Take a look at eligibility here.
https://googleweblight.com/?lite_url=https://www.jest.org.in/eligibility&ei=Hh4AHIrd&lc=en-IN&s=1&m=987&host=www.google.co.in&ts=1465666711&sig=APY536yOfccbpAcl8PzDBtPj1ThUszsJfg

You can follow any of following paths to get a job in DRDO: (a) BTech-MTech in field of Computers, Mechanical, Electronics , Aeronautical, Metallurgy etc. DRDO hires both graduates and postgraduates (b) BSc-MSc in Physics , Chemistry. Biology graduates have very limited scope in DRDO.

Hi buddy, if you had made your mind to go for astrophysics, then the best option is to go for BSC. with Physics honor or a distinction in Physics. But if you wanna route through btech. then better go for Aeronautical Engg., although u always have a option to study astrophysics at Masters level if you have basic physics in u'r graduation. But the best option is via Bsc . This will restrict u' r deviation.

The best ones are at IISC and IISER. The course structure itself is very interesting if you are keen to go for astrophysics. You may also hv a look at IIA, Bangalore.

Hi
The best way is take pure sciences like physics to go for astronomy. IISER, IISC etc are best to pursue subjects like astrophysics. For space technology, mechanical, CSE, Electronics are the core branches If you plan to take b.tech + m.tech route. Institutes like IITs, nits also offer master's in it.

Hi JP
Love to see you have set your future big and different.
I would suggest to go for Aeronautical / Aerospace Engineering from a renowned college then you may pursue higher studies on same. It will take you to close to your dreams.
One more suggestion, if possible just read the 'Wings of Fire' the autobiography of Mr. APJ Abdul Kalam. It will charge you up again.

It is a good suggestion. You are also advised to obtain Flying licence to fulfill your dream. By the way in India , first two astronauts came from Indian Air Force fighter flying branch.