@ EpicFailLord123
There are quite a few things wrong with this, you need to understand both how a bomb works, and how it would react to it\'s environment.
Firstly, an explosion from a bomb is an incredibly fast chemical reaction. The molecules in the bomb react together, break apart and form new molecules. There is not enough space for the new molecules, so they push against each other, and force themselves away from one another. This creates intense pressure and is basically why explosions blow things apart. This also creates the heat output. The molecules are so tightly packed (pressurised), that they\'re vibrating like crazy because they\'re trying to find their own space.
Now think about that for a second, that\'s quite important, it\'s a reaction which creates highly pressurised molecules trying to find their own space.
On Earth an explosion in a field would be surrounded by air. The air molecules would offer little resistance against the explosion. The molecules would push the air outwards with great force, creating a shockwave.
In space, for all intents and purposes a vacuum, there would be absolutely no resistance against the explosion. This means all the molecules from the explosion would be able to push out and move in every direction un-opposed. Molecules move at close to the speed of light, so there will be an initial struggle while they all try to find their own way out from the centre, but since there\'s nothing holding them there for very long, the molecules dissipate into the vacuum of space almost instantly. For an explosion in a vacuum, it\'s that small initial struggle that\'s the only effective bit. Also, as a result of that, the proximity to it\'s target would be highly critical to it\'s effectiveness.
The power behind the explosion comes from the persistant pressure surrounding the reaction which forces the molecules to vibrate against each other for as long as possible. Since this allows the pressure to build, it also directly causes the temperature to increase proportionally.
Any bomb in an enclosed space is orders of magnitude more devasting than if it\'s detonated in air.
Also, just to note, the chemical reactions between the molecules can also release energy in another form - radiation, Beta and/or Gamma. Depending on the frequency/wavelength of that gamma radiation, it could be anything from radio waves, through the visible light spectrum, to x-rays and gamma rays.
TL:DR
A decent analogy would be to compare punching an idiot in the face to punching thin air. You put the same power into each strike. When you hit the idiot, you hope the lesson sinks in. But when you punch the air, it\'s as if you\'re just aggressively waving.
So, no, a nuclear explosion in space would not be a 10 foot invisible fire ball that would last for a year (a mini sun with it\'s own gravity?
); it would be almost the complete polar opposite. It would release just as much light energy and radiation as a nuclear explosion would here on Earth, and it\'s \'diameter\' would expand at almost the speed of light, thus it would be over in a fraction of a second.
