What Is A Supernova ?
Everything in this Universe has to die, universe itself will die one day but do you ever come to know about any star dying in universe anywhere,no! But when a red giant dies,it emits so much light,energy and vibration that it can be seen through simple set of binoculars.And the chain of immense explosions that occurs when a red giant dies is known as a supernova.A supernova occurs when a star collapses because of being unable to conduct fusion in it's core due to lack of fuel.
Ocurence Of Last Supernova
Last supernova occurred in 1604 which was clearly visible with naked eyes on watching with little concentration.Scientists caught this fact by a mistake,they kept tracking the debris of that supernova for years but later on they recognized that it's the debris of explosion.A supernova averagely occurs every 50-100 years in our galaxy and it emits so much light for the moment it explodes that our whole galaxy together emits.The amount of iron atoms that it sends can tear of sun into bits very easily.Supernova occurs in stars that are 1000 times of sun or more.