<p>Take my advice with some seasoning, because my Ph.D. in astrophysics dates back to the early Iron Age (1989), but I would second (third? fourth?) the recommendation for a B.S. in physics over astrophysics.</p>
<p>My B.S. was in physics. I considered doing an self-designed astrophysics major, but the courses that it looked like I needed would have left me only one class short of a physics degree. I figured that the physics degree would give me more employment options and went that route, taking astronomy courses as electives.</p>
<p>Some of my fellow grad students had done their undergraduate degrees in astrophysics, and every one of them had some gaping holes in their training. While they all got caught up just fine, it seemed so obvious that the courses would have been valuable that we were all kind of scratching our heads. It was for that very reason, we were told, that astrophysics graduate admissions committees prefer to see students with physics backgrounds.</p>
<p>That said, if your son has no desire to go on to graduate school, and instead might want to teach or use his astrophysics background in some other way, then a B.S. in astrophysics would probably be just fine.</p>