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PHYSICS APPRECIATION: CHERENKOV RADIATION

I'm a student, enthusiast and massive nerd, this is my best attempt at sharing all the awesome little secrets and tid bits, beyond your average high school science class. (It's cool I swear).

In a visit to Sizewell power station last year (highly reccomend), I learned that nuclear reactors don't glow the radioactive green we see in cartoons:

But rather a brilliant blue:

It's cause is simmilar to that of a sonic boom. Normally, matter can't accelerate past the speed of light, however, the speed of light in water, is much slower than the speed of light in a vacuum (around 75%). This means that, charged particles emitted during nuclear reactions, are able to exceed the speed of light in their medium (water), and things get weird.

Water is dielectric (able to be electrically polarised), so when charged paricles faster than the speed of light travel through it, its particles become polarised. In order to return to their ground state, the particles emit photons.

The photos travel as waves with high frequencies and short wavelengths (remember ROYGBIV?), which tend towards the blue/violet end of the visible light spectrum, hence the blue. (And perhaps even ultraviolet, which we can't see).

If anyone wants me to go more in depth, or if I've made any mistakes, please lmk!!