Everything in the world dies, even the stars. A supernova occurs when a star “dies.” A supernova is the explosion of a star. These explosions release enormous amounts of energy, an amount equivalent to a few octillion nuclear warheads, or a million tons of TNT. A supernova will radiate more energy than our son in his entire life. Supernovae play an important role in the galaxy by being the main source of heavy elements in the universe. Throughout the life of a large star, they create heavy elements within their core. When one of these stars explodes, it releases heavy elements into the galaxy. The elements then disperse and move to create new stars and the cycle continues. Supernovae occur when a star can no longer resist the force of gravity and collapses. There are two types of supernovae. Type II supernovae have hydrogen absorption lines in their light spectrum. Type II supernovae occur in stars whose mass is much greater than that of our Sun. This is an implosion-explosion event. During fusion, outward pressure is created to balance the inward pull of gravity. However, once the star runs out of fuel, it will transform into a red supergiant. While the star is still a red supergiant, its core becomes hotter and denser. During this time, more nuclear reactions occur, delaying the collapse of the core. However, once the core runs out of fuel this time it has nothing left to fuse together and the core collapses. Implosions, or collapses, of the iron cores of massive stars are caused by extreme pressure. When the core collapses, the temperature of the core rises to over 100 billion degrees. The energy from the crushed iron will first be overcome by gravity, but will bounce back through the layers of the star. When it reaches the star's hydrogen envelope, it explodes and a shock wave is produced. Many heavy elements are released by the explosion and are scattered throughout the galaxy to form new Type I Supernovae stars, devoid of hydrogen in their line spectra. These types of supernovae show marked maxima in their light curves, then gradually disappear. There are three subclasses type I, Ia, Ib and Ic. Type Ia, the white dwarf star has a companion star in a binary system. The stars must be close enough for material from the red giant to flow into the white dwarf..