In this episode, Scientific American editor George Musser talks with Caltech Astronomer Josh Simon about dark matter, and about the efforts to try to locate the so-called missing satellites of the Milky Way--small galaxies that have yet to be found in the numbers that the cold dark matter theory predicts. Plus we'll test your knowledge of some recent science in the news. Websites mentioned on this episode include: tinyurl.com/27g9op; www.astro.caltech.edu/~jsimon