how-to topic

Hi, Something that comes out quite a bit, especially when I give talks to 'non-beginners' is how to interpret certain spectral constituents. An example is Balmer lines: I know they represent Hydrogen, but a lot of people say 'so what? Aren't stars full of hydrogen, so it's hardly surprising! What do Balmer (and other series) lines actually have to say about what's physically going on? And again, we know what absorption lines are, but it would be good to have some details about their significance.

Just a couple of examples I've met with, but it would be really good to have a how-to hour about how to understand activity from spectral features - for observers.