Drawing on observations from Chandra, Newton, and previous X- ray observatories, the author provides an accessible introduction to the history, methods, and future of X-ray astronomy. Throughout he emphasizes the importance of Chandra—a space-based telescope like Hubble—and future telescopes like it, and discusses why X-ray astronomy is worth the expense. Schlegel is a research astrophysicist at the Smithsonian Astrophysical Observatory.