There aren't a lot of jobs in the astronomy field if you don't have a PhD in the subject. You can get plenty of other jobs with a degree in astronomy (or better yet a degree in physics, which would give you a lot more job options and actually be better for applying for grad school in astronomy than just an astronomy degree) but not many in astronomy itself. Without a PhD, you could teach high school or community college (with a masters) and work as a data analyst or research assistant for national labs or NASA. With a PhD, you could work for colleges and universities, national labs and observatories, and NASA.