Astronomer

The Indian Institute of Space Science and Technology (IIST) is a leading government-aided institute and deemed university for the study and research of space Science. It is third in ranking after IIT and PEC Chandigarh for doing B.Tech Aerospace engineering. It is a good option to doing Aerospace engineering and joining ISRO.
An astronaut is a person trained by a human space flight program to command, pilot, or serve as a crew member of a spacecraft. Although generally reserved for professional space travellers, the terms are sometimes applied to anyone who travels into space, including scientists also. Following are the general eligibility criteria to become astronaut:
(a)Bachelor's degree from a recognised university in engineering, Science, or mathematics etc. An advanced degree is desirable.
(b)At least 1,000 hours pilot-in-command time in jet aircraft. Flight test experience is highly desirable.
(c)Medically fit
In order to become astronaut you will have to learn flying in addition to B.Tech Aerospace engineering degree. By the way, first and only two astronauts of India are from Fighter branch of Indian Air Force.

An astronaut is a person trained by a human space flight program to command, pilot, or serve as a crew member of a spacecraft. Although generally reserved for professional space travellers, the terms are sometimes applied to anyone who travels into space, including scientists also. Following are the general eligibility criteria to become an astronaut:
(a)Bachelor's degree from a recognised university in engineering, Science, or mathematics etc. An advanced degree is desirable.
(b)At least 1,000 hours pilot-in-command time in jet aircraft. Flight test experience is highly desirable.
(c)Medically fit
Indias first two astronauts were from Indian Air Force Fighter Pilot branch. By the way opportunities for Astronauts in India is almost nil.

Hi Rohith,
First of all, you have to study advanced physics and mathematics. Now, you can either sit in competitive exams and get a good rank, or pursue higher education in reputed institutes until you get a Ph.D. Your current course won't be an obstacle. By first year, I think you mean intermediate or class XI. If yes, then it's perfect. If you mean B.Sc., then it's still cool, you have a lot of time left.
Having a creative mind and good grip on subjects of astrophysics, particle physics, quantum mechanics, cosmology, and basic Newtonian physics will be very helpful. For that, I would recommend reading books on the subject. I'm going to give a recommendation list in the end.
Don't think that only good numbers, good ranks, or tags of top institutes can make you an astrophysicist. There are many research centres and organisations, even ISRO, who don't take these criteria too seriously.
Believe in yourself. If you have the brain of an astrophysicist, you will be recognised just with good knowledge, good percentage, and interest. No need for excellent marks.
It's a very technical field, and I'm myself very interested in this, so I would recommend having a good grasp on interesting topics like string framework, spacetime, nothingness, symmetry, inflation, entropy, etc. After this, make sure you have enough qualifications and marks. You'll have to pay attention to supplementary subjects like maths because they can dampen your overall prospects.
Recommended books:
The Fabric of the Cosmos by Brian Greene: must read, general-level, would explain most complicated topics with the least hassle like about time, quantum mechanics, inflation, etc.
Stardust by John Gribbin: a very beautiful book that's more literature than Science.
A Brief History of Time by Stephen Hawkins: somewhat advanced but needed once you're serious about being an astrophysicist.
You might also try The Theory of Everything and An Elegant Universe.
I hope this helps.
All the best.