Milk Bar

The Milky Way Galaxy is a collection of gas, dust, and about 200 or so billion stars. It's got three main parts: the central bulge (sometimes called the "hub"), the disk, and a spherical halo of stars. Our Galaxy is a spiral, because the disk appears to have great sweeping spiral arms. Surprisingly, we know a lot about the disk. It's hard to map it out because we're in it; imagine being deep in the woods and trying to figure out what shape the forest boundary is. Still, using various different methods, astronomers have been pretty successful getting a feel for it. The inner part is different, though. There's 25,000 light years worth of dust, gas, stars, and assorted junk between us and it, so even seeing those stars gets to be pretty hard. Enter the Spitzer Space Telescope. This is an observatory designed to see infrared light, invisible to ...