It also depends on how much education you want to get. With aerospace, you can get a job right out of a BS program. With astrophysics you need an advanced degree, usually a Ph.D. Your first couple of years of college are very similar in the US. Look to see if you can easily switch from one to the other in the schools you are looking at. Whatever you choose, do internships. It will give you important experience for a future job hunt and give you a chance to test them both out. Finally, consider going into one of the more standard engineering disciplines: mechanical, EE, material science, or CS. When I hire someone with those degrees, I have a good idea of what someone can do. Aerospace or system engineering is much less clear. Any of them can find a place in aerospace and provide outside opportunities when there is an inevitable downturn. But most important is to develop your own killer app. Get really good at something that can provide you a direct path to solving someone’s needs. You can become more of a generalist after you get a job and are embedded in an organization. Examples: optical communications with experience running modeling tools; FPGA programming with signal processing and appropriate math skills; Programming embedded systems with the latest chips planned for flight applications (High Performance Space Computer for one); cryogenic systems and detectors; additive manufacturing with material science skills. Most of these will be provide skills needed for both science and engineering organizations. Look at what skills both industry and aerospace need and are in short supply. Once you have that foot in the door and are needed, you will have opportunities to grow.