Hello,

To become an astronomer you need to take Science group in 11th and 12th with maths and Physics.

Next I will list out some of the courses (UG, PG< etc) that you can do after your 12th:

UNDERGRADUATE

• B.Sc in Astrophysics – 3 year full-time course

• B.Sc in Astronomy – 3 year full-time course

• B.Tech in relevant Engineering

MASTERS

• M.Sc Astronomy

• M.Tech (Astronomy and Space Engineering)

DOCTORAL

• PhD. in Astronomy
• PhD. in Astronomy and Astrophysics
• PhD. in Astrophysics
• PhD. in Atmospheric Science and Astrophysics

SOme of the top colleges that offer courses in astronomy are:

• Indian Institute Of Astrophysics (IIA), Bangalore
• Tata Institute Of Fundamental Research (TIFR), Mumbai
• Raman Research Institute (RRI), Bangalore
• National Centre For Radio Astrophysics, Pune
• Inter-University Centre For Astronomy And Astrophysics (IUCAA), Pune
• Institute of Physics (IOP), Bhubaneswar
• Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bangalore
  
  Good Luck