My suggestion: major in physics. Take one or two astronomy courses for fun if you'd like, but get a very solid grounding in physics first. I am an astrophysics grad student, and I never took a single astronomy course as an undergrad. Sure, it was a bit annoying taking my first graduate level class in astronomy when I didn't know anything about supernova remnants or accretion disks. But I was well-prepared for the first year grad courses in quantum mechanics, E&M, nuclear/particle physics, etc., and I was fairly well-prepared for the PhD qualifier (well...I get the results next week, so maybe I shouldn't speak too soon). The grad students I know with pure astronomy backgrounds tend to have more trouble with the first year of grad school. If you're planning to be a professional astronomer, it's probably a better idea to do your undergrad degree in physics and just take a few astronomy courses on the side. All the astronomy professors I know in my department tell me that they have much less trouble with people who come in with physics degrees than they do with the astronomy folks. It's possible to pick up the necessary astronomy knowledge on the side. But quantum mechanics isn't something you can learn in your spare time outside a classroom (unless you happen to be a genius).
However, maybe you're interested in quitting with a bachelor's degree. I would still suggest physics or perhaps even physics and engineering. Be warned: with just a physics BS your job prospects aren't all that great. But they're even worse if you have an astronomy degree. At least with a physics degree you can get a job at an engineering firm, in software development, or even as an analyst. With an astronomy degree I'm not really sure what you can do except graduate school. Don't get me wrong, I love astronomy. I wouldn't be majoring in astrophysics if I didn't. But no matter your career path, physics is a far better bet than astronomy at the undergraduate level.