What Causes a Supernova Explosion?
A supernova occurs when a super massive star explodes. It is a dramatic end to a star’s life.
Supernovae (which is the plural form of supernova) become very bright and cause an enormous burst of radiation that can outshine an entire galaxy before disappearing. The outburst usually lasts about a month and expels much of a star’s remaining matter at an extremely high rate of speed – typically around one tenth the speed of light. This creates a shock wave that effects the interstellar medium in the vicinity of the supernova.
So how does this explosion happen? The right ingredients need to be in place. Supernovae are extremely rare – occurring only once every fifty years within a galaxy the size of our own Milky Way.
They can only happen when an aging massive star can no longer generate energy from nuclear fusion and undergoes a rapid gravitational collapse. This collapse releases potential energy that heats up and throws off the outer layers of the star in the form of an enormous explosion.
While it is difficult to predict when the next supernova may occur, scientist have speculated that there are a couple of good candidates in our galaxy. Rho Cassiopeiae, Eta Carinae, RS Ophiuchi, U Scorpii, VY Canis Majoris, Betelgeuse, Antares, and Spica all could explode within the next thousand to hundred million years – which is a very short time on the galactic scale!