Astronomy

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.

Which course you are talking about? Anyway you can check this link to get an idea:- http://www.iiap.res.in/phd2013_beta/?q=node/2 Good luck.