The San Francisco Amateur Astronomers is one of those societies that truly make learning enjoyable. Its name might summon images of Trekkies at a sci-fi convention, but club members are supernice and hail from all kinds of professional backgrounds. You've likely seen them cavorting around the city when something cosmological is about to occur — you can simply identify them by their enormous painted telescopes, which are sometimes handmade but always effective. Best of all, they're so darned accessible and informative that it's fun to stop and gab with them about Leonid meteor showers or just life in general. If you're interested in, you can always sign up and revel in the society's myriad star parties and field trips to dark sites in Northern California (which is definitely a big deal, considering all the light pollution that has mucked up the skies for modern-day Galileos). They also hold their annual Astrophotography, Literary and Art Awards, an event that's invariably kooky and ethereal, a bit like really good interpretive dance for science and technology types. You can get your fair share of scholarly fun with presentations on stuff like solar eclipses and black holes, so you can live out all your vicarious Stephen Hawking fantasies.