A new video released by NASA’s Chandra mission shows how Cassiopeia A has evolved over more than a dozen years in X-ray light. Cassiopeia A, which is located about 11,000 light-years from Earth, is the most studied nearby supernova remnant. When the original star ran out of fuel, it collapsed onto itself and blew up as a supernova, possibly briefly becoming one of the brightest objects in the sky. Although astronomers think that this happened around...
