I have a hard time explaining my understanding of what astronomers do when I am asked by family or other people I know. The first and most obvious answer I give is that they observe things, usually stars, in the sky so they can later study them. Most people, when I say this, probably don't realize that there are a lot of different kinds of stars that are formed and behave differently. The differences in these stars make them interesting for study. Why should one star form one way and another star form a completely different way? Learning about the forming conditions are just one jobs of the astronomer. Other astronomers are interested in how things first started billions of years ago. Learning about how other galaxies were formed and how they work gives us insight about our own galaxy. Then there is the question of what is space itself made of? Before the 20th century or so, astronomers thought space was made up of the aether but that was found to be false. The constant inquiry of astronomers has lead to a more accurate understanding about the very nature of space itself.
Those are just a few of the things that come to mind immediately when I am asked about what astronomers do. Of course, one can't think about astronomy without thinking of telescopes and pretty pictures as well. If most people don't really know what astronomers do then they also have less of an idea about how the telescopes work as well. So knowing how to operate the telescope is also a part of what astronomers do, at least if they want to collect any data.
Astronomers also employ math to come to conclusions about their data, or to support new ideas that are in the process of becoming theories. I always have to remember not to overlook this aspect when describing astronomy to other people, that astronomy is not just collecting data with a bunch of cool technology.
Although for me, the hardest part about trying to explain what astronomers do is to try and put it in some sort of context that most people will care about or be able to relate to. For most people, understanding how stars form and such is rather useless knowledge; it's (most likely) not going to cure cancer and it doesn't help run a business. To me though, learning and developing a better understanding of our universe is more important than managing a business. After all, we are all living in this giant expanse of space and to limit our interests to the mundane, everyday activity of ourselves is to miss the point of what it means to be inquisitive beings trying to expand our knowledge.
