If a civilisation living on a planet orbiting a nearby star a few light years away detonated a 50MT thermonuclear bomb in space near the planet with direct line of sight to the Hubble space telescope, say, would the explosion be detectable by Hubble in any way (visual, gamma ray burst, infra red, x-ray)? (assuming we knew it was coming and were ready for it).

 

And if so could they, and us, use this method to communicate with each other in a form of nuclear "morse code" using several bombs (albeit with a 4-year period waiting for the reply).

 

I presume that no lasers or other man-made radio waves could carry that sort of distance and still be detectable?

 

If you put square miles of tin foil behind the bombs you could focus its energy in one direction.

well, hubble could probably see it but it would probably just register as a tiny tiny tiny tiny solar burp unless it was somewhere where there wer no stars at all. lasers would carry that far and theoretically forever.

it does give a distinct EM spike yes, but you`d have to be listening for it.

I dont think so, I think it would be too insignificant. Hell, hubble can't even see a planet the size of earth around a star; the star itself is too bright. A nuke going off would be super super tiny compared to how much the planet reflects.