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Why your bathroom taps have been lying to you for years

Do you ever get the sense that you’re being lied to? That those around you have fed you untruths your entire life and no-one else seems to question it?

I’m not talking about the latest twists in the current crazy political landscape or any half-baked conspiracy theories about the Sun’s evil, unseen twin. No, I am talking about something much closer to home: your bathroom taps.

Bathroom taps often use red for hot and blue for cold

We use them everyday and they’ve been quietly whispering to us since childhood that red is hot and blue is cold. But is that really true? Not quite. Let’s take a look at some hot things. A blowtorch, for example, with its strong flame is very clearly blue. A normal open flame is yellow. Yet only when a fire starts to cool down and die out does it then glow red.

Although they are not on fire, stars are the same. The hottest stars – those with the greatest surfaces temperatures – shine blue. Stars with temperatures in the mid-range – like the Sun – are yellow. Red stars are the coolest – either because they are small or because a big star has swollen during the red giant stage of its death throes.

Next time you look up at a starry sky try and pick out the red ones. These massive dying stars are the perfect illustration of the need to ignore you bathroom taps!

Stars by temperature. As a general rule hot, big stars are blue and small, cool stars are red. But any red star you can see in the night sky is a big star that is cooling during its death throes (red dwarfs star to dim to be seen unaided).

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