スミソニアン博物館さんのインスタグラム写真 - (スミソニアン博物館Instagram)「Twenty years ago this week, @nasachandraxray released the "First Light" image of the Cassiopeia A supernova remnant 11,000 light-years from Earth. Cas A (its nickname) is the glowing debris field left behind after a massive star exploded. When the star ran out of fuel, it collapsed onto itself and blew up as a supernova. Shortly after the Chandra telescope was launched aboard the Space Shuttle Columbia in 1999, astronomers directed the observatory to point toward Cas A. The image revealed, for the first time, a dense object called a neutron star that the supernova left behind. Chandra has returned to Cas A over the last 20 years to continue to learn more about the physics of the explosion and the change in the cosmic object. #Chandra20」8月28日 5時42分