Your child is too young. Don't rush him. Like already mentioned by others there are lots of courses which you can enroll your son into once he has finished his schooling.
Meanwhile, you can teach him about space in a manner which he’ll enjoy and understand. For instance there’s Space Camp in India. They take kids to the US Space and Rocket Centre at Huntsville. There they are given hands-on astronaut training. They are also taught basic mathematics and physics related to the space. I think your kid will love the experience and this will also help him gain confidence and conviction for his future. They have a group on Facebook, might help you to decide. Anyways here’s their link
http://spacecampindia.com/ . Best of luck!