Here is a more general and brief background on supernovas in the universe that we have seen:

The universe twinkles with these cataclysms. They happen every second or so, usually in some unimaginably remote galaxy, blazing as bright as hundreds of billions of stars and creating a fireball that expands and cools for months.

We’re lucky that they rarely strike close to home. The last supernova in our own galaxy exploded in 1604, rivaling Jupiter’s brightness in the night sky and deeply impressing Johannes Kepler, the pioneering astronomer. A nearby supernova—within a few light-years—would bathe the Earth in lethal radiation.

So do these gamma rays effect us or will rays in the future effect us?  The comments on this thread are all over the place and entertaining.  This is one of those topics that will be debated for  a long time.