Earth's atmosphere often interferes with the reception of radiation, so once receivers could be positioned beyond the atmosphere, a new era in the study of the universe began.
The first cosmic X-rays were picked up in 1962 by a detector aboard a small rocket. Their source was later found to be Scorpius X-1, a binary-star system that is the brightest X-ray source in the sky.
Satellites, including Japan's Ginga, the European Space Agency's EXOSAT, and Germany's ROSAT, have provided intriguing insights into X-ray sources, such as black holes, neutron stars, and supernova remnants. Scientists will image some of these sources in 1998 with the first Advanced X-ray Astrophysics Facility, AXAF-1.
Ultraviolet astronomy began in earnest in December 1968 with the Orbiting Astronomical Observatory-2, which returned data covering one-sixth of the sky. From this, a catalog of bright UV sources was compiled. Subsequent missions glimpsed sources of extreme ultraviolet radiation—hot stars, supernovae, the active cores of galaxies, and quasars (the intensely energetic centers of far-off galaxies)— and produced more than 90,000 ultraviolet spectra.
In December 1990, an instrument package aboard the space shuttle Columbia provided spectroscopic observations in the far- and extreme-ultraviolet wavebands. The Astro mission also made images ofUV sources and assessed how UV radiation is scattered by cosmic dust and strong magnetic fields. The Extreme Ultraviolet Explorer was launched in June 1992 and has surveyed the entire sky, mapping sources of extreme UV radiation. It is being used to study white and red dwarf stars, eruptive variable stars, and thin interstellar gas.