Supernova - Interesting facts

Term supernova refers to explosive death of some massive star characterized by an enormous amount of emitted energy. Supernova explosion emits incredible amount of energy- more energy that our Sun emits for its entire lifetime. The expanding shock waves from supernova explosions are also capable to create the formation of new stars. Our Sun, for instance, does not have enough mass to end its life as supernova. The earliest recorded supernova, SN 185, was recorder by Chinese astronomers in 185 AD.

The astronomers believe that supernova explosion occurs approximately twice every 100 years in our galaxy. This means that supernova explosion are relatively rare event within our Milky Way galaxy. Most galaxies have a supernova every 25 to 100 years.

The scientists have estimated that in order for Earth's ozone layer to experience damage from a supernova explosion, the blast would have to occur less than 50 light-years away. Luckily, all of the nearby stars capable of going supernova are located much further than this. The nearest supernova candidate is IK Pegasi (HR 8210), located at a distance of 150 light-years.

Theoretically, if there would to occur such near supernova explosion this would cause huge damage to our planet's ozone layer from massive X- and gamma-ray radiation that would induce a chemical reaction in the upper atmosphere converting molecular nitrogen into nitrogen oxides, causing major depletion of our ozone layer and exposing life on our planet to harmful ultraviolet light in the sun's rays.

The gamma ray radiation as a result from supernova explosion can also result in a birth of a black hole. As matter falls toward a nascent black hole, some of it becomes accelerated into a particle jet of enormous power, even capable to drill its way completely through the star before the star's outermost layers even have begun to collapse. A gamma-ray burst, if directly pointed at Earth, could cause major damage from up to 10,000 light-years away. So far, the closest gamma ray burst on record, known as GRB 031203, was 1.3 billion light-years away. Gamma ray bursts are thought to be the most powerful blasts in the Universe.

The closest supernova explosion witnessed in almost 400 years occurred in 1987, when a light from an exploding star in a neighbor galaxy, the Large Magellanic Cloud, reached Earth. It was appropriately named Supernova 1987A.

The main reason why astronomers study supernovas is to find some kind of signature behavior that would enable them to identify stars before they explode. Scientists can still only speculate whether stars give off a clear signal of impending blast or not.