You’ve got an important job to do, and you’d better get compensated well for it. And you will. Not as much as a doctor or lawyer, and certainly not as much as a Wall Street bigwig, but better than your average bear. As a physicist, you will make around 100k a year. A bit less if employed by a college or university, but potentially quite a bit more if working for the government. You know, like in one of those Top Secret laboratories that you see in James Bond movies. However, contrary to what you may have picked up from the movies, very few physicists are chimpanzees. (You really need to start watching less low-brow cinema.)
Obviously, what degree you have attained and where you are at in your career also determine how much you are making. If you got a degree in physics but it was only a bachelor's, and you are applying the knowledge you acquired there to engineering or computer science, you may be pulling in more in the 70-75k range. But if you have a PhD, you'll be much closer to that 100k mark as a teacher, and if you hold a critical, supervisory position on a research project of great national importance, 150k or more is totally realistic.
There are similarities between what many physicists and astronomers do, and not surprisingly, there also similarities between their salaries. If you find yourself getting pulled more in the direction of astronomy (perhaps by some mysterious gravitational force), you can expect to make roughly the same amount as a physicist. Oh, and when preparing to ask for a raise... reach for the stars.