http://www.rssboard.org/rss-specification 720 http://ecuip-xtf.lib.uchicago.edu/xtf/search?expand%3Dsubject;f1-subject%3DConcepts;f2-associated-Lesson%3DX-Ray%20History Results for your query: expand=subject;f1-subject=Concepts;f2-associated-Lesson=X-Ray History Thu, 01 Jan 1970 12:00:00 GMT http://ecuip-xtf.lib.uchicago.edu/xtf/view?docId=grxr/EMS-penetration-atmosphere/EMS-penetration-atmosphere.dc.xml Only visible, radio, and some infrared radiation penetrates the atmosphere. Ultraviolet photons, X-rays, and gamma rays do not. While observations at any wavelength benefit from instruments in space, detection of celestial of ultraviolet, X-ray, and gamma-ray sources require instruments in space. The development of rockets led to our ability to place these special instruments in space. http://ecuip-xtf.lib.uchicago.edu/xtf/view?docId=grxr/EMS-penetration-atmosphere/EMS-penetration-atmosphere.dc.xml Thu, 01 Jan 1970 12:00:00 GMT