Picture yourself during the early 1920's inside the dome of the Mount Wilson Observatory. ... Humason is showing Shapley stars he had found in the Andromeda Nebula that appeared and disappeared on photographs of that object. The famous astronomer very patiently explains that these objects could not be stars because the Nebula was a nearby gaseous cloud within our own Milky Way system. Shapley takes his handkerchief from his pocket and wipes the identifying marks off the back of the photographic plate.
The destruction of this planet would have no significance on a cosmic scale: to an observer in the Andromeda nebula, the sign of our extinction would be no more than a match flaring for a second in the heavens: and if that match does blaze in the darkness there will be none to mourn a race that used a power that could have lit a beacon in the stars to light its funeral pyre. The choice is ours.