Ghosts by Light Echoes
"Using recently discovered faint light echoes, astronomers have divined when three known supernovas occurred. The visible echoes are described as being much like sound echoes. They're created when light from the explosion expands outward and reflects off dust and travels toward Earth." --Moroni Sanchez
Ghosts by Light Echoes is licensed under a Attribution-Noncommercial-Share Alike 3.0 Germany License.