Any possibility to shift from computer science to astronomy and astrophysics? please suggest option

It's possible but a tough task trying giving subject test to backup ur interest

*look for.

It is possible, but you have to have a lot of prior research experience in order to get into decent PhD programs. Also, it will be difficult since you wouldn't have had physics courses in your undergrad, which grad schools looks for. Moreover, apart from the general GRE, you'll have to appear for the Physics GRE and score >800 (~85 %ile) in order for your profile to become even remotely competitiv... See more