Much to my surprise, there is substantially less information on this topic on the internet than I initially thought there would be. Wikipedia has very little to go on, and I can't find any papers or serious discussions of this topic. There are many people asking similar questions on websites like yahoo answers, but the answers to these questions are shaky at best and never cite sources. Also, let it be clear that I am not talking about high altitude nuclear explosions that were technically in space, as these programs deal almost entirely with their effects on the atmosphere and had little to say on the effects in a vacuum. The question is simple: Would a nuclear explosion in the vacuum of space be more effective, less effective, or comparably effective than on Earth? It seems to me that there are several pros and cons: The pros: -There would be nothing blocking the intensity of the gamma rays -The range on the weapon should increase (a Wikipedia article said this was a benefit of the high-atmospheric nuclear testing that was done) -Charged particles and shrapnel (whatever shrapnel is worth) would move at extremely high speeds and not be slowed down The cons: -No atmospheric shockwave -No atmosphere to heat up To me, it sounds like it may be more effective at annihilating human life and electronic devices than actually damaging structures. This begs a couple of more questions: From a military perspective, would it be easier or harder to shield a craft from a nuclear blast than on Earth? Is it possible (viable) with current technology to shield against these gamma rays? Would conventional explosions be more or less effective? From an "Armageddon" perspective, would close-proximity nuclear blasts even be a viable option for blasting apart or diverting asteroids or comets? I would love to discuss this with anyone willing.