Hello Aparna,

In order to gain admission to any of the top undergraduate programs in Aeronautical or Aerospace Engineering, you will need to 

• Give an English language proficiency examination (either TOEFL,IELTS Academic or PTE Academic). Scores from all three of these exams are generally accepted in universities around the world. You will have to obtain a score satisfying the minimum requirement for the university to which you are applying.
• Obtain a senior secondary percentage which is equivalent to the minimum requirement of the specific university. In most international programs, AISSC and ISC are accepted. A few other states boards are also accepted in some universities. International Baccalaureate scores are also generally accepted universally.
• In case your senior secondary percentage qualification does not meet the university requirement, you will have to take either the SAT or ACT exam. 

Some of the best universities for an undergraduate education in Aerospace or Aeronautical Engineering are:

• Massachusetts Institute of Technology (USA)
• Harvard University (USA)
• University of Cambridge (UK)
• The University of Tokyo (Japan)
• University of Michigan (USA)
• Tsinghua University (China)
• National University of Singapore (Singapore)
• Delft University of Technology (Netherlands)
• Caltech (USA)
• KAIST (South Korea)

First you need to decide which course, Universities you are interested then I can help you regarding to Study in Abroad.

Good Luck!