Why is the sun yellow?

As anyone who knows me is aware, I’m a bit of a science nerd. I’m a biologist by education and inclination, but other aspects fascinate me as well. For example, here is a post from a theoretical astrophysicist about the colour of the sun.

There are plenty of stars that are bluer than the Sun, and many, many more that are redder, but as far as we can tell, the true color of the Sun is almost perfectly white, but slightly more yellow/red than blue.

But — and this is important — not from the surface of the Earth! Our atmosphere turns direct sunlight slightly yellow! The effect is worse near sunrise or sunset, and is least at high noon on the summer solstice (when the Sun is nearest its zenith), but it’s always present, and it always yellows the Sun slightly.

White sun, white clouds

On the same topic, Phil Plait discusses the lack of green stars in his blog Bad Astronomy.


Green stars not allowed

And it comes around to biology, because colour is all about perception.

When we look at the Sun, we see all these colors blended together. Our eyes mix them up to produce one color: white. Yes, white. Some people say the Sun is yellow, but if it were really yellow to our eyes, then clouds would look yellow, and snow would too (all of it, not just some of it in your back yard where your dog hangs out).

Ain’t science grand?


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