This image shows the latest results as colored dots superimposed on an artist’s conception of the Milky Way. Red dots show stars that formed when the Milky Way was young and small, while blue shows stars that formed more recently, when the Milky Way was big and mature. The color scale shows how many billion years have passed since those stars formed. Image via G. Stinson (MPIA)
Cygnus Loop Nebula | NASA Remnants of a supernova which occurred between 5 and 8,000 years ago. Astronomers say this explosion was so massive it would have easily been visible with the naked eye in the night sky.