Most great explosions that happen in space-based science fiction movies are accompanied by an almighty ‘ka-boom!’, but you already know that this is only possible in Hollywood space.
In reality, an explosion in space would be deathly silent.
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On Earth, the most damaging part of an explosion is the shock wave it creates in the air.
This is when the chemical reaction that makes an explosive material explode creates a highly pressurised, hot gas that expands rapidly, travelling outward from the explosion as a wave of destruction.
The shock wave is carried by the particles in the air and will keep going until it loses its energy, giving us the blast radius.
But in outer space, there are very few particles.
The initial explosion will still involve a high-pressure gas at high temperature, but there won’t be any atmosphere to carry the shock wave.
This means an explosion in space won’t be as destructive as it would be on Earth.
The target would still explode, sending shrapnel out into space on a trajectory that could, in theory, go on forever if nothing stood in its way.
With no oxygen in space, an explosion wouldn’t produce a roaring fire.
It could ignite the oxygen inside a spaceship, though, so there would be some flames in certain circumstances.
While the detonation of the spaceship Nostromo at the end of Ridley Scott’s Alien, or the huge explosions during space battles in Star Trek are spectacularly unrealistic, 2014’s Interstellar is a good example of a movie getting an explosion in space nearly right.
The scene occurs in complete silence, and fire appears only where oxygen is escaping from the exploding ship.
What are your favourite sci-fi tropes, and how scientifically accurate are they really? Let us know by emailing contactus@skyatnightmagazine.com
This article appeared in the February 2025 issue of BBC Sky at Night Magazine
