Field Guide to X-ray Astronomy A brief overview of the history behind X-ray Astronomy: from the differences between optical and X-ray telescopes to descriptions of good Web sites on the subject. http://chandra.harvard.edu/xray_astro/ - More
X-Ray Astronomy Article from Wikipedia which explains what this is and the history behind it. http://en.wikipedia.org/wiki/X-ray_astronomy - More
X-Ray Astronomy: 40 Years of Seeing the Invisible Article by Robert Roy Britt that looks back at the history of X-Ray astronomy. http://www.space.com/scienceastronomy/astronomy/xray_anniversary_020618-1.html - More