Cosmic X-ray background

Cosmic X-ray background, X-ray radiation pervading the universe. In 1962 the first X-ray detectors were flown above Earth’s X-ray-absorbing atmosphere in a sounding rocket. In addition to discovering the first cosmic X-ray source, Scorpius X-1, astronomers were also puzzled by a uniform glow of X-rays with energies greater than 1.5 keV (1 keV = 1,000 electron volts) coming from all directions. The radiation did not appear to arise from identifiable objects. The X-ray background seemed...