Supernovae, colossal explosions of massive stars and one of the most violent phenomena in astronomy, will be explored at the University of Colorado at Boulder's Fiske Planetarium in July. CU-Boulder Professor Emeritus Richard McCray will present "Supernovae" on Thursday, July 6, and Friday, July 7, at 8 p.m. During the show McCray will describe what astronomers have learned about supernovae from ancient and modern observations. He also will talk about why all the heavy elements in the universe, including those on Earth, were produced by supernovae explosions.