what kind of jobs are available for someone in astronomy with a bachelors or masters degree?

There aren't too many jobs in astronomy you can get without a PhD (and you'll certainly need one to do research in the field), but since a good astronomy degree would give you a solid background in math, physics, and some computer science, you'll be eligible for a bunch of other jobs related to those fields.  With a bachelors or masters in astronomy, you could teach high school (or community college with a masters) or work as a support tech or data analyst for a national lab or NASA.  But there aren't a ton of those jobs around.  You'll need a PhD in astronomy to do research in the field, and if you're going to get a PhD in astronomy, a physics major is actually better than an astronomy major (although a double-major in the two is best).  It better prepares you for a graduate program in astronomy, astrophysics, or physics, all of which can lead to a career in astronomy.