Am I the only one immediately thinking "war"?
These bursts might be some start detonations in a war between two alien species, which would be really frightening..!
These bursts might be some start detonations in a war between two alien species, which would be really frightening..!
In any case it's far more likely this is some natural phenomenon.
So the flashes in the sky could be enormous depth charges, thrown blind into the abyss to reduce narrow probability counts or ferret out the hidden home worlds.
Since an attack can be total, and come from anywhere, and you can never know if you fully succeeded, the peoples of Glurk-42 had a nervous disposition.