You need to get yourself a Ph.D. in astronomy. While doing that, your dissertation advisor will provide you with advice on what kinds of jobs will be available, although most of the jobs that are likely to exist will either be at universities, planetariums, or government agencies (e.g. NASA).

Getting into a Ph.D. program in astronomy can be approached from several different directions in college as an undergraduate. For example, if you want to study stars, you probably should major in physics; if you want to study planets, you should look into an undergraduate degree in geology; if you want to study cosmology, perhaps you should get yourself a background in mathematics (or physics). In any case, you'll probably want to take college classes that bridge the fields - for instance, if you're majoring in geology because you want to study other planets, you should take enough astronomy to know what the other planets are and how they interact with each-other and the other things in the solar system (for example you ought to make sure that you understand why Jupiter's moon Io is as volcanically active as it is, or what it means that Neptune is an "ice" giant).

Astronomy is a pretty uncommon major, so you should ask a college course counselor (ideally an astronomy professor) where to go and whom to take classes from. Most of the University of California schools - certainly UC Los Angeles, Santa Barbra, Santa Cruz, and Berkeley - have pretty good astronomy programs or have in the past, but you might want to look into the University of Arizona or Hawaii, too, especially for graduate school. Still, as a 10th grade high school student, you have plenty of time to decide, so make sure you take a good look around before you choose (also, keep looking around - schools change, so which one is best for right you now might not be best when it's time to apply to a Ph.D. program, and vice-versa).

And make sure you take AP physics in high school, and as much math as possible. Also, take geology if you can (my high school offered it, but not all high schools do).