When you gaze up at the night sky, all the stars you see are part of our own Milky Way galaxy. The Milky Way holds 100 to 400 billion stars! Learn about how galaxies form, the perplexing mysteries of black holes, and how galaxies can differ from one another with science expert Velma and the rest of the Scooby-Doo gang. Part of the Scooby-Doo Space Discoveries series.