This image, created from data obtained from NASA's Chandra X-ray Observatory and the European Southern Observatory's Very Large Telescope, shows a part of the roughly circular supernova remnant known as RCW 86. This remnant of an exploded star may be the one observed in 185 AD by Chinese astronomers. By studying it, astronomers gained a better understanding of new details about the role of supernova remnants as the Milky Way's super-efficient particle accelerators.