Gamma ray bursts are the most powerful explosions ever detected in the Universe, but astronomers have been uncertain what causes them. There are two theories: collisions between neutron stars, or supernova explosions from very massive stars. New data gathered by the European Space Agency’s XMM-Newton X-ray observatory have helped rule out the first, and maybe confirm the second. By analyzing the afterglow of a recent burst, astronomers were able to detect chemical elements which are found in supernovae.