What would a nuclear explosion look like in the vacuum of space?

Answer 1

I know sound cannot travel in a vacuum but light can.
On Earth, the interaction with the surrounding matter, be it air, water, or whatever, means that the initial energy is very quickly, in a few milliseconds, spread out over a fairly large amount of matter, no matter what the nature of the explosive.This material, typically air, forms a luminous fireball that expands at the speed of sound in the air that has been heated by the explosion, which is faster than the speed of sound in ordinary cool air. The result is a shock wave at the surface of the fireball. As the fireball expands it compresses and heats the surrounding air, while losing energy by radiation and also because of the work it is doing on the outside air, all of which causes it to cool. Eventually it cools to the point where it is no longer luminous, the shock wave moves out ahead and makes the BANG! that we hear and that may knock down buildings, and a cloud of swirling debris, smoke, and maybe brownish nitrogen oxides are left behind.
In the space, the first few milliseconds proceed as they would in air (say), but then the transfer of energy to the surrounding air never takes place. As a result the initial small, intensely hot fireball simply keeps expanding at very high speed, and the expanding gases and any fragments fly off in straight lines. The fireball cools by radiation at first, but as its density drops it becomes so transparent that radiation is suppressed. For a chemical high explosive, the expansion speed would be a few thousand feet per second. Visually the effect would be of a very brief, brilliant flash in a region only a little bigger than the actual extent of the explosive material. Of course there would be no billowing swirling smoke, and any fragments would almost certainly be moving too fast to be visible. The effect would probably be something like that of a big flashbulb.
For a nuclear explosion, the fireball would radiate mainly in the x-ray and ultraviolet, which are not visible to the eye, although the visible part of the radiation would produce a blue-white flash. The expansion speed would be many hundreds or thousands of times faster than for a chemical explosion, so that the time scale would be less than a millisecond. All the material near the source would be vaporized, so there would be no fragments. If the explosion was truly in space, and not in a tenuous atmosphere, then viewed from a survivable distance the effect would probably be similar to, but even less spectacular than, a chemical explosion.
The idea of blowing up an asteroid is not the way to do it in the real universe. Many of the fragments would remain on a collision course and like the blast from a shotgun; the fragments can do up to ten times as much damage as the original, intact object.
"Stand-off" nuclear explosions are favored by some scientists and might work with both solid and rubble-pile objects.
"Rubble-Pile" asteroids and finds that blowing them up with bombs may be much more difficult than with asteroids made of solid rock. It is a bit like the difference between hitting a sandbag and a solid sandstone block with a sledgehammer -- the sandbag absorbs the impact with little disruption but the sandstone block shatters.
A nuclear bomb is detonated several hundred yards away from the object.
One thing most scientists agree on is there is no need to maintain an arsenal of nuclear weapons in space ready to intercept rogue asteroids. They also point out that there are ways to deflect asteroids that don't require nuclear explosions and we should be looking at these methods more closely.
In theory, an asteroid that is found to be on a collision course with our planet can be deflected to avoid an impact.
The deflection involves changing the asteroid's course with a sideways push or, preferably, changing its orbital speed so that it arrives before or after, rather than when Earth crosses its path. In either case the deflection is far more effective if it can be carried out years or decades ahead of the predicted collision.

Answer 2

Awesome, it would look awesome. The shape of the explosion would depend on the weapon. But, in general, unless engineered to go off differently, the shape would be spherical. There would be no mushroom cloud, as you indicated, because there would be no cold air to trap the explosion and cause it to expand out like the top of a mushroom. There would be no traditional shock wave because gas, like air, is required for a shock wave. There would be a different sort of shock caused by the impact of the heat and radiation flux emitted by the explosion. There would still be a lot of heat and some of that would be in the visible range like infrared. There would also be a lot of light as the intense energy would be manifest over the entire spectrum of visible light depending on the energy levels. And as the explosion is in a vacuum, there would be no ejecta and debris from the ground to obscure the light. This would be a spectacular and relatively long lasting flash because it takes time to deplete all that energy; it would not be a puff. BTW: It does not take matter to have light. Light is energy; all it takes is energy in the visible light range. And a nuke has plenty of that. ABTW: Nuclear and atomic explosions are the same thing. When an atom splits, it's the nucleus of that atom that does it.

Answer 3

It would be very large and violent! Without the pressure of the atmosphere or the gravitational effects of earth, the explosion's spherical size would increase at an astonishing rate. Additionally, the sonic energy (vibration and sound) of the explosion observed on earth would be contributed to the force of the explosion itself!
Suppose that your fist is the explosion. With your other hand closed tightly around your fist (earth), try to open your fist. What happens?
Now try the same thing with just your fist alone (space) and try opening it with the same amount of force as before. See the difference?

Answer 4

Here are a couple of places to look. They tell you their theories about the look of the explosion and 'sound' as it were.

Answer 5

A big blast of white light,that would slowly die out as it expanded and cooled.

Answer 6

an explosion would be pure heat energy,
no shock wave, no THUMP, just heat

Answer 7

Ever seen a star?