Over 2 decades of Chandra X-ray Observatory views of the Crab Nebula and Cassiopeia A have been time-lapsed. The Chandra team explains here. Credit: NASA/CXC/A. Hobart Congress averts government ...

A SEARCH for X-ray emission from galactic objects on April 29, 1963, disclosed two localized sources, one of which appeared in Scorpius and the other in the direction of the Crab Nebula.