The Sun is Green

May 17, 2013 at 2:00 am 9 comments

By Chad Upton

I know, the sun doesn’t look green. But, keep in mind the sky looks blue and we know it’s not really blue. The sky appears blue for the same reason some people’s eyes look blue — an optical illusion known as the Tyndall effect.

sun is green

When scientists measure the wavelength (color) of the sun, the peak output is in the transition area between blue and green (about 500 nanometers). So, technically, the sun is green-blue. But, why doesn’t it look green?

It doesn’t look green because it also emits light at other wavelengths, enough that our eyes blending these wavelengths together perceive the combination as white light. Because of the way our eyes work, we can only see a green star (such as the sun) if its photons are limited to the green range. Therefore, you’ll never actually see a green star (as green).

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photo: Roxanne (cc)

sources:, discover magazine, blogstronomy

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9 Comments Add your own

  • 1. Charlie Himmelfarb  |  May 17, 2013 at 2:40 am

    Does that explain the “Green Flash” I have seen at sunset just as the last bit of sun drops below the horizon?

  • 2. Zurk  |  May 17, 2013 at 10:49 pm

    I wish the sun looked green….

  • 3. chrisbma  |  July 3, 2013 at 3:18 pm

    The sun is not green. That would indicate that the sun emits one spectral color: green. The sun emits all colors. In physics, we call this color “white”. If you are referring to the peak color, then you have to be careful. The peak color is not a concrete concept and depends on whether you are in frequency space or wavelength space. In wavelength space, the peak color of sunlight before hitting our atmosphere is violet. In frequency space, the peak color is green. Which one is right? They are both right. This illustrates the pointlessness in assigning special meaning to the peak color of light with a broad spectrum. Sunlight is white. If sunlight were green, then we would not be able to see the redness of flowers or the blueness of butterfly wings under the illumination of sunlight.

    Also, the sky is blue because of Rayleigh scattering + eyes that don’t violet that well, and not because of the Tyndall effect.

  • 4. Reaper  |  March 16, 2016 at 3:48 pm


  • […] Oricât de nebunesc ar suna această afirmație să nu uităm faptul că și cerul pare albastru cu toate că lucrurile nu stau chiar așa. Efectul Tyndall este vinovat pentru această iluzie optică prin care cerul pare să aibă culoarea albastră sau pentru care unii oameni par să aibă ochii de altă culoare, notează […]

  • 6. MARTIN MCCLELLAN  |  November 6, 2018 at 1:57 pm

    I know it’s green. I use to stare at it as a child. No I’m not blind but as a child I did not know it is bad for your eyes.

  • 7. Aaron Tyler Warren  |  June 3, 2019 at 4:04 pm

    I read a report from NASA that said, the visable light output of the sun’s radiation isn’t blue-green, it emits mostly yellow and green photons in the visable spectrum… I don’t know what the color temp of sunlight is in outer space, but I think the blue green color temp is within the atmosphere… maybe?

  • 8. Alisami  |  February 1, 2022 at 9:06 am

    I think it is true

  • 9. Charles Gomez  |  January 17, 2023 at 2:55 am

    Like Mr McClellan , I too did the same, several times, when I was little (around 10 or so, when curiosity has no upper limit), surprised to discover by direct experience (and exposition) that, in fact, the sun is really green.

    Yet, although I have not develkoped eyes issues either, doing the same thing now would be very dangerous, and I’d advise seriously against it. In these last 40 years, CFCs and who knows how many more pollution wastes have critically damaged our atmospheric protective layers, so I guess nowadays the risk of serious harme can be real.


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