The Effects of Nuclear Explosions on Space

I believe that unless it's something close, or it's something to a planet, or maybe close to, I don't know, like a nebula, maybe it will push away that. But other than that, maybe the only thing in space that will happen, if it's in the vacuum of space, would be gravitational waves. Well, you won't get a mushroom cloud, that's for sure, because that only happens in the atmosphere. So I imagine like a big, bright ball of light that will flash for a second and disappear.