Historical Supernova Remnant
RCW 86 is thought to be a remnant of an exploding star that the Chinese discovered in 185 AD. There was some editing done to this photograph to show the different composition of the supernova. The blue and green are X-ray energies and the red and yellow are cooler temperatures in infrared. Because there is a lot of iron present in this supernova but not a neutron star, it suggests that it is a type Ia supernova (thermonuclear explosion that destroys a white dwarf star). RCW 86 is 8,200 light-years away and has a radius of about 50 light-years.