I'm a PhD student doing astronomy.
Favorite quotes:
One thing to note is that comet-hunting used to be at least 50% of astronomy (back a couple hundred years ago). Now there might not be 50 people in the world who research comets.
~Chris White
From my astro classes:
It took the smartest brains our species has ever produced thousands of years to come up with our modern understanding of physics.
and
Star systems are like relationships. When only two bodies are involved, things work out pretty nicely. However, when you add in a third body, things get a lot more complicated and sometimes more fun.