In general, you can earn a BS in Aerospace/Aeronautical Engineering within four (4) years at an accredited College or University. However, the course-load is significant; and this is especially true at the top schools. Thus, most people spend five (5) years earning their BS. If you want to go on to a MS or PhD, then add on 2 to 4 more years depending on the specific area of study and the educational program. Also, the top schools in the world all have cooperative education programs (co-op) wherein you work a total of 4 to 5 semesters for a real-world company. While at these companies, you get paid well (not at the same level as a real engineer, but usually better than min-wage) and you get to see what life is like doing a real job outside of all the book-work and theoretical stuff you learn in your AE classes. Doing this adds generally one (1) more year to your studies but it can be worth it in the long run with legit business contacts as well as real world experience to apply to your first real engineering job.