Can I do this with my degree?

I am about to start my senior year of high school. I want to be an astronomy/astrophysics major. But the school that i will most likely go to doesn't have that program (I'm probably going to University of Wisconsin Milwaukee). They do have a physics program -- like most schools. Now, would I be able to get the physics degree, and then be able to go to a graduate school that has the astronomy/astrophysics program and get a masters, and then PhD in that area of study, even though I would have a bachelors in physics? Or should I try my hardest my first two years, get my general ed out of the way, and transfer to U of chicago, or UW madison?