Physics and Astronomy

Even though astronomy and physics are intimately co-mingled, they are not quite the same. The fundamental aim of physics is to uncover the fundamental laws of Nature, and to apply these rules in situations where they are helpful. Astronomy, in contrast, is concerned with a particular object which we find -- the Universe -- and everything in it, in much the same way that geology is concerned with a particular object, in that case the earth. There is a discipline of geophysics, just as there's a discipline of astrophysics, but in geophysics and astrophysics, the physics is often not an end in itself, but rather a tool used to understand what is there. Physics is used in the design of instruments, the interpretation of the data the instruments produce, and finally in the construction of the grand theories which explain the evolution of stars, galaxies, and the universe (or the earth!).