The Milky Way's buried treasures

When I was younger, I'd haul my 'scope out to the driveway and peruse the heavens. Some of my favorite targets were open clusters: loose aggregations of stars that had dozens or even hundreds of members. These stars are all in the family, born by the same cloud of gas and still bound together by their own gravity. A lot of these objects are big and bright, easily visible in binoculars -- those tend to be close to us in space -- and others fainter, harder to spot. Most of those latter ones are just farther away, but some are partially obscured by galactic dust, which robs them of light, like a curtain in a window partially blocking the light form outside. I used to wonder how many open clusters the Milky Way sported. Thousands, I figured, and I also guessed a lot had been cataloged. But how many were behind such thick curtains of dust, hidden from our view? Some estimates are that there as many as 30,000 such groups. And now we're starting to find them.