<p>Aerospace Engineering and Astrophysics are two very different disciplines. To succeed in Engineering you need above average intelligence, a strong work ethic and can obtain satisfaction from creating tangible devices. You can work as an Aerospace engineering with a bachelors degree. A career in Astrophysics is on a completely different plane in its intellectual demands and is almost certainly the most difficult major there is. If you are not the smartest person you know there is little chance that you can earn the PhD that is the minimum qualification for an astrophysicist. Remember, astrophysicists study the most difficult things to understand that are encountered in science such as the Big Bang, Dark Matter, Dark Energy and both the large scale structure of the Universe and atomic processes that are responsible for it.</p>
<p>You will need an understanding of General Relativity and Quantum Mechanics that a far more difficult than anything you would encounter as an engineer. There are only a few hundred people working as astrophysicists in the entire country. It could be there are not many positions in the field to be filled or that the number of people with the intellect to be an astrophysicist is so limited.</p>