SUPERNOVA

Within galaxies, as stars were being born, others died...often in enormous cataclysmic explosions. These explosions, called supernovae, are important to the evolution of galaxies because they distribute all the common elements such as oxygen, carbon, nitrogen, calcium, and iron into interstellar space. Explosions of especially massive stars also create and distribute heavier elements such as gold, silver, lead, and uranium. The supernova pictured here is of a smaller type, used by astronomers to determine distance. This one appears to us now as it looked when the universe was about five billion years old.