# Is the Sun really green? **URL:** \ **Category:** Factual Questions\ **Created:** [January 7, 2003, 5:19am UTC](https://boards.straightdope.com/t/is-the-sun-really-green/147107 "2003-01-07T05:19:04Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![jclune](https://avatars.discourse-cdn.com/v4/letter/j/9dc877/32.png) [@jclune](https://boards.straightdope.com/u/jclune)\ **Post date:** [January 7, 2003, 5:19am UTC](https://boards.straightdope.com/t/is-the-sun-really-green/147107/1 "2003-01-07T05:19:04Z")
Dust scatters shorter wavelengths more so than longer ones. This is the reason the sky is blue. The reason the sun is first orange then red at sunset is because the dust particles between you and the sun are deflecting longer and longer wavelengths of light more and more as the light you are looking at passes through increasing amounts of atmosphere. That effect should also be occurring during the day, meaning that blue light is being taken out of the color you are seeing in the sun (which is what is making the sky blue). So, without atmosphere, would the sun appear to have more blue in it…shifting its “real” color towards green? I have heard this explanation given in an astronomy class and wonder if it is true and how large the effect is. This professor said that pictures of the sun and its light from space show it to be noticeably “greener”. Can anyone confirm or deny? ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [January 7, 2003, 6:28am UTC](https://boards.straightdope.com/t/is-the-sun-really-green/147107/2 "2003-01-07T06:28:04Z")
As you said, sunlight passes through increasing amount of atmosphere as the sun gets lower in the sky. When it’s 30 degrees above the horizon, the path is twice as long as when the sun is directly overhead. You’ll probably notice a slight change in color but not much, right? That’s more or less the difference between the color of the sun as seen from the ground and from space. Also, if you add blue to sunlight it’d be bluish white, not green. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [January 7, 2003, 8:25am UTC](https://boards.straightdope.com/t/is-the-sun-really-green/147107/3 "2003-01-07T08:25:37Z")
I think I’m right in saying that the peak (visible) wavelength of the sun’s light is somewhere in the green, but as long as there are other wavelengths involved, we’re going to perceive it as something else; even if the output were composed of two pure wavelengths; one in red and one in green, we wouldn’t perceive it as ‘reddish green’ - it would just look yellow. ---
**Author:** ![Urban\_Ranger](https://avatars.discourse-cdn.com/v4/letter/u/e9c0ed/32.png) [@Urban\_Ranger](https://boards.straightdope.com/u/Urban_Ranger)\ **Post date:** [January 7, 2003, 8:31am UTC](https://boards.straightdope.com/t/is-the-sun-really-green/147107/4 "2003-01-07T08:31:42Z")
Sol is a yellow star, so there’s where its peak output. Blue, white, and green stars are hotter while red and orange ones are cooler. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [January 7, 2003, 9:00am UTC](https://boards.straightdope.com/t/is-the-sun-really-green/147107/5 "2003-01-07T09:00:44Z")
> [@](#): > > \*Originally posted by Urban Ranger \* > **Sol is a yellow star, so there’s where its peak output. Blue, white, and green stars are hotter…** Not quite. “Yellow” is not a pure color but a mixture so you can’t have a peak at yellow. Sunlight peaks in the green, but it also has significant amount of blue and green light (it’s a smooth continuum) so it appears yellow. If it were hotter, there would be more blue and less red light so it would be a blue star. If it were cooler it’d be red. There’s no such thing as a green star. [rant]…which is why it’s ridiculous to claim that the average color of the universe is green! Why did any astronomer believe that result?![/rant] ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [January 7, 2003, 9:02am UTC](https://boards.straightdope.com/t/is-the-sun-really-green/147107/6 "2003-01-07T09:02:03Z")
Sorry, that should be “Sunlight peaks in the green, but it also has significant amount of blue and **red** light…” ---
**Author:** ![Desmostylus](https://avatars.discourse-cdn.com/v4/letter/d/c57346/32.png) [@Desmostylus](https://boards.straightdope.com/u/Desmostylus)\ **Post date:** [January 7, 2003, 9:24am UTC](https://boards.straightdope.com/t/is-the-sun-really-green/147107/7 "2003-01-07T09:24:09Z")
> [@](#): > > \*Originally posted by scr4 \* > **"Yellow" is not a pure color but a mixture so you can’t have a peak at yellow.** What exactly does that mean? For example, what color is a sodium D-line emission? ---
**Author:** ![Desmostylus](https://avatars.discourse-cdn.com/v4/letter/d/c57346/32.png) [@Desmostylus](https://boards.straightdope.com/u/Desmostylus)\ **Post date:** [January 7, 2003, 10:24am UTC](https://boards.straightdope.com/t/is-the-sun-really-green/147107/8 "2003-01-07T10:24:50Z")
> [@](#): > > \*Originally posted by Mangetout \* > \*\*I think I’m right in saying that the peak (visible) wavelength of the sun’s light is somewhere in the green, but as long as there are other wavelengths involved, we’re going to perceive it as something else; even if the output were composed of two pure wavelengths; one in red and one in green, we wouldn’t perceive it as ‘reddish green’ - it would just look yellow. \*\* > [@](#): > > _Originally posted by Urban Ranger_\*\* > Sol is a yellow star, so there’s where its peak output. Blue, white, and green stars are hotter while red and orange ones are cooler\*\* Both almost right. The peak emission is around 0.5 microns, which is green. However, the human eye has a sensitivity peak in the yellow, so it _looks_ yellow to us. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [January 7, 2003, 10:31am UTC](https://boards.straightdope.com/t/is-the-sun-really-green/147107/9 "2003-01-07T10:31:57Z")
> [@](#): > > \*Originally posted by Desmostylus \* > \*\*What exactly does that mean? For example, what color is a sodium D-line emission? \*\* You’re right, please ignore what I said above - obviously my brain isn’t working today. My apologies for posting in this state.