I'm pretty sure that 99% of that galaxy didn't feel a thing. The size of m82 is 40000ly and a largest supernovae will affect( not necessarily destroy stuff ), 3

I'm pretty sure that 99% of that galaxy didn't feel a thing. The size of m82 is 40000ly and a largest supernovae will affect( not necessarily destroy stuff ), 3000ly around itself. Relevant: http://en.wikipedia.org/wiki/Near-Earth_supernova http://en.wikipedia.org/wiki/Near-Earth_supernova