Hello Priya !

If you have interest in Astronomy , after 12th you should opt for graduation in Science or Engineering subjects as a primary step.

After that , you can look for master level courses like M.Sc Astronomy, and M.Tech (Space Technology and Applications), as well.

Now there are ample of job opportunities in this field if you are talented enough like ,  in firms like Bhabha Atomic Research Centre (BARC), Inter-University Centre for Astronomy and Astrophysics (IUCAA), NASA, Technology Information, Forecasting and Assessment Council (TIFAC) etc.

Hope it helps !