With a title like the King of the Monsters and a filmography spanning over six decades, Godzilla is a pretty iconic guy across the board. But he wouldn’t be the kaiju we know and love without his famous atomic breath. In any given Godzilla movie, it’s usually a bluish or greenish blast that obliterates enemies and buildings. That blue color means that Godzilla’s signature attack is much more destructive than it looks.

In my latest Because Science, I’m taking on the physics of an atomic belch. We’ve studied mushroom cloud-producing explosions for some time, and we know that most of the energy of the blast goes into the shock waves and thermal radiation. That’s what’s causing the damage you’re likely familiar with. In his movies, Godzilla’s atomic breath doesn’t seem to cause blast wave-like damage. So what is the real destructive aspect? The color is the key.

A small but appreciable percentage of an atomic blast’s energy comes from ionizing radiation–radiation that has the energy to knock electrons off of atoms and destroy molecular machinery like DNA. When certain gases are ionized, they emit light, sometimes bluish greenish light. So if Godzilla’s atomic breath is nearly always that color, it means that enough radiation is spewing out of its mouth to coerce the air into giving up photons. And if that’s the case, atomic breath is even worse than it looks–you’ll have to watch my latest episode above to find out why!

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