A cataclysmic event that terminates the life of a star with a mass of about 12 Suns or more with a huge explosion in which most of the star is blown apart. When the star has exhausted the light elements for fusion, heavy elements (e.g. iron) begin to accumulate in its core, from which the star gains no more energy by fusion. Thus, it cannot resist gravitational pressure and the core collapses into a massive neutron star or even a black hole. The shock wave that this collapse causes in the outer layers of the stellar material will violently blast them away into the surroundings. The exact reasons of stellar core collapse vary according to the properties of the star, its size and its chemical composition. A supernova shines so intensely over almost the entire electromagnetic spectrum that a supernova hundreds of thousands of light years away can be seen with the naked eye in the Earth’s sky.