Comment: Prof. Jeanloz is really passionate about planetary astrophysics! You'll learn a lot in the course, but the material is challenging (the problem sets took hours every week, even as a senior with a background in engineering and exposure to much of the material in upper division courses). However, the Prof. is very generous with the course - there are no exams, just a final 3 min presentation and 3-page paper (in retrospect, it was hard to write such a short paper/presentation since you have to be really concise!). I learned a lot from this class, although the course is designed to be more of a survey of topics rather than going in-depth. It'll help you try a little bit of everything and help determine what topics you like/don't like. Go to TALC! You'll learn so much better from other students and the GSI if you can discuss the course topics/reading and explain things to others.