Can I do M.Sc in physics to become an astronomer after doing B.Tech in aeronautical engineering? I am a student of class 12 and I am studying in India. I want to be an astronomer and I know that I have to get a B.Sc, then M.Sc, and then Ph.D in astronomy. I have also started to learn the python programming language. I came to know that there are less opportunities for research in astronomy, since many organizations like ISRO not only employ scientists, but also employ engineers to make satellites and spacecrafts. I will try my best to become an astronomer, but to have life security (if i am unemployed), can I do aeronautical engineering so that I can even get employed in ISRO? After having a degree in engineering and after doing engineering can i do M.Sc in physics and then i start preparing to be an astronomer?

Let me tell you about myself a bit, I love to study science and I love to learn about stars (I have also watched documentaries on astronomy like "How the universe works" and "Cosmos"). I also love aircraft so aeronautical engineering would also be a job that I would love. And please tell me should I also do some extra courses which would enhance my skills as an astronomer?
It is good to see that you are interested in astrophysics at an young age. 
No problem with you doing the clichéd BE that everyone in India is forced with, you can still get your PhD in Astrophysics. 

Your 4 years of B.Tech aeronautical is going to be tough, so be prepared for it. In the mean time, keeping in mind your aim of becoming an astrophysicist, prepare yourself equipped with programming languages, especially Python/C++. The reason I say this is because you don't need too have much of an astronomy background to do M.Sc Astronomy, but you definitely need to have a good knowledge in a programming language. 

There are websites like Course Era or EdX and plenty more on the internet that can help you with learning python/C++ in an interactive way. Go for it, and trust me it will help you a lot.

As a final year student doing my PhD in Astrophysics (hailing from India) let me tell you the information I have acquired over the years.

With regard to the Masters/PhD in Astronomy/Astrophysics, the procedure is quite different in different countries. 



Procedure within India

There are plenty of Universities in India that offer you a Masters course in Astrophysics. 

Almost all the details required are summarised neatly in THIS PAGE, 
so I am not going to go through the list of things required. 



Procedure for Europe

You would need:


All your original mark sheets attested by the college/university (Bachelors, Masters, etc)
Two/three recommendation letters, and the number of letters depends on the university you are applying to. 
A completely filled application form.
IELTS scores (depends on country)
Statement of purpose, as to why you want to do the course.


This is pretty much all you need for Europe. For certain universities, you might be having a Skype interview, wherein they might ask you about the stuff you know. 



Procedure for USA:

When it comes to the USA, it gets quite complicated!

You will need:


All your original mark sheets attested by the college/university (Bachelors, Masters, etc)
Two/three recommendation letters, and the number of letters depends on the university you are applying to. For most universities it will be online forms that your professor needs to fill after he/she receives the mail.
A completely filled application form. This is going to cost you somewhere from around 50-80 dollars depending on the university.
GRE scores (both general GRE and subject (Physics,Chemistry etc.) GRE) that you can send to the university directly online by paying money (25 Dollars for each university). Only a few universities accept you without a subject GRE.
IELTS/TOEFL scores. TOEFL scores can be sent online, but if you are taking IELTS you have to go to British council and have them send it. 
Statement of purpose, as to why you want to do the course. 




So it depends on where you want to apply. I would recommend you to apply to both, to increase your chances. For Europe, the chances of you getting through depends on the country you apply. For USA, the chances of you getting through solely depend on your GRE scores. It doesn't matter whether you are a gold medallist in your Bachelors, it all boils down to GRE. If you fail there, your entry into USA will be difficult.  

One advantage of Europe is that, mostly, the PhD is only for 3/4 years, depending on the country. Whereas in the USA, it is mandatory for the student to write exams in the first year, teach/be a research assistant in the second year, and only in the third year start the PhD project. 



To search for PhDs in Astrophysics depends on the country you are applying for. But as a start, you can have a look at http://jobregister.aas.org/. PhD calls, internship calls, post-doc positions, etc. related to astrophysics will be posted here during the start of every month. 



With regard to your question 


  can I do aeronautical engineering so that I can even get employed in ISRO?


Yes you can definitely do that. ISRO not only employs aeronautical engineers, but also people who have completed their BE in electrical and electronics and also computer science. 

Have a look at THE CAREERS WEBSITE OF ISRO to get more information.



Good luck with your future!