displays of raw energy—a single star can briefly shine more brightly than a billion Suns and can even outshine an entire galaxy of stars. These spectacular bursts of energy play an essential role in the creation of planetary systems, and of life itself. Solar systems, and planets like Earth, are constructed from heavy elements such as iron and oxygen, which only form in the interiors of stars. These heavy elements would never find their way into planetary systems without forces like supernova explosions to fling them into interstellar space.