Blast from the Past

Bright 'pearls' of light mark the expanding shock wave from Supernova 1987A, an exploding star that was first seen from Earth in February 1987. As the shock wave races away from the site of the explosion at thousands of miles per second, it rams into gas that was expelled from the star long before the explosion. The collision makes the gas glow. Astronomers continue to study the aftermath of the explosion to understand more about the original star, the physics behind its demise, and how material from the star is scattered into space. Hubble Space Telescope snapped this image in 2003. [NASA/P. Challis, R. Kirshner (Harvard-Smithsonian CfA)/B. Sugerman (STScI)]