The Chandra X-ray Observatory (CXO), previously known as the Advanced X-ray Astrophysics Facility (AXAF), is a Flagship-class space observatory launched on STS-93 by NASA on July 23, 1999. Chandra is sensitive to x-ray sources 100 times fainter than any previous x-ray telescope, enabled by the high angular resolution of its mirrors. Since the Earth’s atmosphere absorbs the vast majority of x rays, they are not detectable from Earth-based telescopes; therefore space-based telescopes are required to make these observations. Chandra is an Earth satellite in a 64-hour orbit, and its mission is ongoing as of 2018.
Chandra is one of the Great Observatories, along with the Hubble Space Telescope, Compton Gamma Ray Observatory (1991–2000), and the Spitzer Space Telescope. The telescope is named after the Nobel Prize-winning Indian-American astrophysicist Subrahmanyan Chandrasekhar.
Before NASA’s Chandra X-Ray Observatory, observation in these tiny wavelengths had turned up a uniformly glowing background. When astronomers started using the spacecraft for ling-duration deep-field surveys in 1999, they resolved the x rays into a plethora of individual extragalactic sources powered by supermassive black holes—quasars—and other active galactic nuclei.
500 Cool Astronomy Things 