Why do astronomy at all?
This, believe it or not, is a common question at our "Ask an Astronomer" sessions in the visitor centre at Jodrell Bank. There are several answers to this, some of which are: it's interesting, there are technological spin-offs, and it (hopefully) inspires children to develop an interest in science or engineering.
The research itself can be a bit incomprehensible to non-specialists, so public outreach relies on enthusiastic experts explaining what they do in non-technical language. As I've commented before, it wouldn't be a bad thing if the funding councils made it a condition of funding that you have to do some public outreach.
Some astronomers do this already of course (on the other hand, some hate the idea and avoid the whole public interaction thing at all costs). Last week there was a paper on astro-ph describing a project to bring science into schools using astronomy, and a collaboration between the teachers and astronomers.
The scheme consists of four visits to the school by a real astronomer during the school year. The first visit is very similar to something that the organisers of the Researchers in Residence scheme did: before meeting the researcher, they asked the kids to draw their idea of what a scientist looked like. Then the researchers come in and spend some time with the class, doing activities and explaining what they do, and then the kids are asked to draw their idea of a scientist again. The second picture is almost always dramatically different to the first. No more elderley men with strange hair, a lab coat and smoking test tubes! Progress!
Seriously, there is a lot that can be done with astronomy in schools. With a bit of imagination it can be used to cover a variety of different areas within the curriculum, something we have been trying to do with the astronomy and space Go For It for the Guides as well. If only more astronomers, and scientists in general, were willing to put in a bit of effort now and then.