Brightest Galactic Event

Gamma Ray Bursts (GRB) are extremely energetic flashes of Gamma Rays which are observed in distant galaxies. These are "Brightest Electromagnetic" events known to occur in the Universe. Till now no GRB's has been spotted in our "Milky Way Galaxy".

Occurrence :

Most GRB's are believed to originate during "Supernova"  when Fast rotating stars of High masses collapse at the end of their life time to become a "Neutron star, Quark star or a Black Hole". Most of the GRB's occurred far away from the earth nearly billions of light years away which indicates that the explosions are extremely energetic and are extremely rare.

They release the "Total energy" our Sun releases in it's whole lifetime in just a short span of time ranging from 10 milliseconds to several minutes.

Only a Very Few GRB's occur every million years in each galaxies.

Incoming danger :

It has been theoretically hypothesized that a GRB in a Nearby galaxy pointing towards earth may endup in a mass destruction possibly the end of "The World". The highly energetic gamma rays can destroy the Ozone Layer exposing all creatures on the earth to harmful UV rays. They are strong enough to cause "Genetic Mutations" and even may kill all of us at instant.

Fortunately there are no such big stars within our galaxy or in nearby galaxies to cause GRB's :)