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The Debunker: Is the Sun Yellow?

by Ken Jennings

Take a break from your fun in the August sun to ask yourself: what do I really know about this giant glowing globe of plasma shining down on my picnic/game of Ultimate Frisbee/clothing-optional beach right now? Given that the Sun is what makes life on Earth possible, it's appalling how much misinformation we've been fed about our nearest star. Speaking of our nearest stars: Ken Jennings, that one guy from Jeopardy!, may not be as bright as the Sun, but he's an expert on debunking myths and misconceptions. All month, he'll be lighting up our stellar misconceptions regarding the sun.

The Debunker: Is the Sun Yellow?

You'd think you'd be on pretty safe ground calling the Sun yellow, wouldn't you? It certainly looks yellow. Scientists call it a "yellow dwarf." Even Superman says he gets his super-powers from Earth's yellow sun—so much brighter than the red sun of his native Krypton.

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In fact, sunlight contains all the colors of the spectrum, which is why a prism (or raindrops) can separate it into an entire rainbow of color. Our sun is burning hydrogen into helium at a temperature of about 5,500°C, and stars of that heat actually peak in the green portion of the spectrum. The Sun is putting out more green photons than any other color.

The atmosphere scatters a lot of the shorter-wavelength photons—blues and violets—before they get to our eyes, which is what makes the sky blue. Losing that short-wavelength light pushes the remaining light into the warmer part of the spectrum: yellow if the sun is overhead, sometimes even orange or red when it has more atmosphere (near the horizon) or pollutants to shine through.

But what if you could get rid of that pesky atmosphere? You'd be dead, of course, but you'd finally see the Sun in its actual color: white. Sunlight is almost pure white, not yellow, to human eyes, and that's it would look from space if you could ever get that vantage point. NASA sometimes color-corrects photographs of the sun to give it the yellow-orange glow that we earthlings expect, but they've been lying to us for years. Just like that yellow sun wearing sunglasses on the evening weather! I hate that guy.

Quick Quiz: Nine countries have incorrect yellow suns on their national flags. Can you name one of the two countries—both in Asia—that have scientifically accurate white suns?

Ken Jennings is the author of six books, most recently his Junior Genius Guides, Because I Said So!, and Maphead. He's also the proud owner of an underwhelming Bag o' Crap. Follow him at ken-jennings.com or on Twitter as @KenJennings.