Our galaxy, the Milky Way, is a spiral galaxy. Its main components are a bulge at the center, a thin disk and a thick disk where the spiral arms are located, and a halo. The thin disk is believed to be the youngest component of the galaxy. So imagine how surprised astronomers were when they found some stars in it almost as old... read full story
"These ancient stars in the disk suggest that the formation of the Milky Way's thin disk began much earlier than previously believed, by about 4–5 billion years,"