It turns out that the answer to my question is much simpler than I thought. My hunch was that water in the atmosphere somehow bent light to conform to its crystalization pattern. This was off. As Blaylock put it, "The answer isn't out there, the answer is in your camera."

My camera, I have discovered, has a hexagonal aperture, which causes a hexagonal diffraction pattern, not a hexagonal light scattering pattern through gasses, which, I realize now, makes absolutely no sense in regular experience. The Hubble, on the other hand, is designed in such a way that creates a square diffraction pattern, though it has a circular lens.

The next question, which I'd realized without seeing the signifigance of, was phrased by Blaylock. "Stars have a diffraction pattern, but galaxies don't. Why do you think that is?"

The answer was immediately obvious to me, but may not be to the reader. A star is, for all intents and purposes, a fixed point of light. A galaxy, however, though just as bright, from the right distance, is much larger and much further away. The individual stars that we do see do create diffraction patterns of their own, but the effect is smeared and blurred by the sheer distances involved. To clarify, the angular distance between one star on one side of a galaxy and another star on the other side of the same galaxy is just enough, over billions of light years, to blur out any diffraction pattern. If the galaxy itself shows any diffraction pattern at all, it's insignifigant and hard to see.

A star creates a diffraction pattern when a galaxy doesn't for the same reason a laser going through a double-slit creates a diffraction pattern while a regular lightbulb shone on a double slit doesn't. The distance differences, the uncertainty of original position of light as it tries to interfere, gives you a clear image.