If you're in high school, take physics and all the math you can. In college, astronomy 101 is a good place to start. It won't require physics or calculus, but the upper level astronomy and physics classes will if you decide you'd like to take more classes. Keep in mind there aren't a really any jobs in astronomy if you don't have a PhD in the field (you can work as a data analyst with a bachelors or masters, or teach high school or community college, or get a somewhat-unrelated-to-astronomy job in another field without one) so if you do want to do astronomy for a living, you'll be school for a while.