<p>A pure astronomy major will be somewhat less math intensive than physics or astrophysics. Generally, a pure astronomy major will have to take the introductory calculus based university physics sequence, as well as the full calculus sequence. Differential equations and linear algebra will be required in some programs. Beyond that though, the rest of the courses would usually be astronomy courses. There will still be a lot of math in the astronomy courses, but it will be the math as it is applied to those specific courses, rather than learning the pure math behind the physics or the astronomy. </p>
<p>With astronomy though, the more math and physics you know, the better off you’re going to be, so it would be advisable to use elective credits for additional physics courses.</p>
<p>edit-Most astronomy departments will have courses within the astronomy department that are basically “physics for astronomers” type courses. For instance, many schools will have a course on General Relativity that is geared for astronomy students, and deals primarily with the applications of GR to astronomy. General Relativity is probably the most important part of physics for an astronomer to know, beyond the introductory calc based physics. The issue there though, is that to really study GR, you need at least something of an education in classical mechanics and electromagnetism.</p>