Dear aspirant hope you are doing well..

Educational requirements for becoming an astronaut:

• You will have to take up science stream with Physics, Chemistry and Mathematics as your core subjects after your 10th grade.
• After that do your Bachelor's degree from a recognised university.You can take up subjects like physics, chemistry, mathematics, biology etc. in your Bachelor's. However, it  is suggested that in your Bachelor's you do courses in aerospace or aeronautical engineering and avionics and then your Master's and Ph.D in the same.
• Trying scoring the highest possible score in all the competitions or academic examinations you give. Since there are multiple people applying for this and this job is in huge demand, the chances of you getting in are very low and thus to maximise your chances, you should secure maximum possible marks.
• After your graduation you can join the ISRO by giving the Joint Entrance Examination (JEE). For joining NASA will have to appear for the NASA Space Physical.
• Try getting an internship in these fields so that you know the basics of the field work involved, it will give you the required experience to pacify the needs of the job and will further enhance your chances of employability.
• It will be advisable to either join the Air Force or Indian Space Research Organisation (ISRO) prelimnarily and then join an astronaut training programme. This will give you the required field training.

Colleges offering courses in Astrophysics/Aeronautics are:

• Indian Space and Research Organisation (ISRO), Bangalore
• Osmania University, Hyderabad
• Andhra University, Vishakhapatnam
• Punjabi University, Punjab
• IIT Bombay, Mumbai

Hope it's helpful..

Thank you