This animation illustrates how the powerful gravity of a massive galaxy cluster bends and focuses the light from a supernova behind it, resulting in multiple images of the exploding star. If the cluster were not present, astronomers would detect only the supernova light that is directed straight at Earth and would see only a single image of the supernova. In the case of the multiply imaged supernova, however, the light paths are bent by the cluster's gravity and redirected onto new paths, several of which are pointed at Earth. Astronomers, therefore, see multiple images of the exploding star, each one corresponding to one of those altered light paths. Each image takes a different route through the cluster and arrives at a different time, due, in part, to differences in the length of the pathways the light follows to reach Earth.
Credit: NASA, ESA, and G. Bacon, Z. Levay, and A. Feild (STScI); and S. Rodney (JHU) and the FrontierSN team; T. Treu (UCLA), P. Kelly (UC Berkeley), and the GLASS team; J. Lotz (STScI) and the Frontier Fields team; and M. Postman (STScI) and the CLASH team
Publication: March 5, 2015