# What Color is the Sun? **URL:** \ **Category:** Factual Questions\ **Created:** [February 1, 2010, 4:56am UTC](https://boards.straightdope.com/t/what-color-is-the-sun/527210 "2010-02-01T04:56:57Z")\ **Posts on this page:** 19\ **Page:** 3
**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\ **Post date:** [February 3, 2010, 12:36am UTC](https://boards.straightdope.com/t/what-color-is-the-sun/527210/41 "2010-02-03T00:36:38Z")
> [@panamajack](#): > > Sorry, I missed this reply earlier. I’ll let **Chronos** explain his own words if he wishes. > > The point, though, is that you _are_ seeing the blue light. That light obviously cannot be coming at you directly from the sun, since it’s been scattered and clearly visible from somewhere other than the sun in the sky. Therefore that light, at least, cannot be part of what you perceive to be the color of the sun when you look at it (assuming you could do so safely), nor could it have been ‘lost’ from that view of the sun. Read pretty much every post I’ve posted here. I’ve said from post number two on foward you have 2 major things. Direct sunlight (minus the scattered/filtered part) and the scattered part scattering all over the clear blue sky. THATS what I’ve been saying all along even though I am told I am wrong. I shortly expect the guys squeezing sunlight out of cucumbers to come along. This reminds me of the russian rich guy thread where he would use lasers to thrwart poparatzi. Much ivory tower hand waving how it couldnt work. I took out my measely laser pointer and found out it royally fucked up my camera. Then there was the thread where I mentioned intensity interferomety and the experts were sure there was no such thing. Then LG butts found exactly what I was talking about and the thread died a quite death. I expect chirping crickets here too any minute. ---
**Author:** ![panamajack](https://avatars.discourse-cdn.com/v4/letter/p/47e85d/32.png) [@panamajack](https://boards.straightdope.com/u/panamajack)\ **Post date:** [February 3, 2010, 1:50am UTC](https://boards.straightdope.com/t/what-color-is-the-sun/527210/42 "2010-02-03T01:50:34Z")
I have no idea what you’re going on about, **billfish** , and I think the only thing wrong you’ve said is “light I am NOT seeing”; I just replied to point out that you are seeing that light. Though it’s unclear whether you’re claiming that the entirety of the blue in the sky comes from sunlight that otherwise would come directly to a single point where you are, which was why I expanded on that in my last post. However, I mainly wanted to post to correct an error in what I said, which also pertains to that. I suggested that none of the direct sunlight scattered comes to you. There certainly could be some of the sunlight directed at you that gets scattered back at you in the blue sky you see; but the majority comes from light directed at other parts of the Earth. ---
**Author:** ![Spectre\_of\_Pithecanthropus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/spectre_of_pithecanthropus/32/12343_2.png) [@Spectre\_of\_Pithecanthropus](https://boards.straightdope.com/u/Spectre_of_Pithecanthropus)\ **Post date:** [February 3, 2010, 2:08am UTC](https://boards.straightdope.com/t/what-color-is-the-sun/527210/43 "2010-02-03T02:08:15Z")
The colors of extrasolar stars are best seen in terms of how they contrast with different-colored stars in the same area of the sky. For instance, Aldebaran, as a Class K star is reasonably close to our sun’s Class G. When you look at it, its orange-yellow color isn’t immediately obvious, but if you look next at the bluish white Pleiades, the difference in color is evident. In Orion, the contrast between red Betelgeuse and blue Rigel is quite clear. If you could travel to Alpha Centauri, for example, and look back at the Sun, it would look yellowish compared to blue Eta Cassiopeia (near which it would appear to be in the sky). As for what color it looks to be from Earth, it’s oddly interesting to me that the folk wisdom of its yellowness agrees with what the astronomers say. As a kid I sometimes dared to glance at the sun long enough to discern its hue, and it seemed bluish more than anything. ---
**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\ **Post date:** [February 3, 2010, 2:09am UTC](https://boards.straightdope.com/t/what-color-is-the-sun/527210/44 "2010-02-03T02:09:17Z")
> [@panamajack](#): > > I have no idea what you’re going on about, **billfish** , and I think the only thing wrong you’ve said is “light I am NOT seeing”; . I am not (to a very small value) seeing light **from 6000 miles away** , besids of course, the shit from 93 million miles away. Thats what I meant. Yes, I know that when I look up at the blue sky in some random direction I am seeing light that was headed bout 20 miles to the east/whatever of me (from the sun), Rayleigh scattered off a molecule and then headed my way. Thats “local”. Thats not a fracking sunset somewhere else far far far far far far far far far far far far far far far far far far far far far far…away. Damn, the guy who said the sun was paisely is ahead of half the herd here. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [February 3, 2010, 3:23am UTC](https://boards.straightdope.com/t/what-color-is-the-sun/527210/45 "2010-02-03T03:23:12Z")
> [@](#): > > The colors of extrasolar stars are best seen in terms of how they contrast with different-colored stars in the same area of the sky. For instance, Aldebaran, as a Class K star is reasonably close to our sun’s Class G. When you look at it, its orange-yellow color isn’t immediately obvious, but if you look next at the bluish white Pleiades, the difference in color is evident. In Orion, the contrast between red Betelgeuse and blue Rigel is quite clear. For a really great example, look at Alberio (the head star of Cygnus, or alternately the base of the Northern Cross if you look at it that way) through a telescope. It’s an optical double, composed of a yellow star and a blue star of just about the same brightness. ---
**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\ **Post date:** [February 3, 2010, 3:43am UTC](https://boards.straightdope.com/t/what-color-is-the-sun/527210/46 "2010-02-03T03:43:06Z")
Some simple experimental results. I took my digital camera and took a picture of direct sunlight reflected onto a white piece of paper (but not exposed to the blue of the sky). I then took a picture of the paper out in the yard, exposed to direct sunlight AND the bright blue sky. Not surprisingly (to me) the two photos are obviously different. They are different enough that I dont even need to see them side by side to tell the difference. The second photo has a decidedly bluer tint to it. Or, put another way, the first photo has a decidedly yellow tint to it. I can even go in and look at the color histograms and its obvious the second photo has more blue in it. That tells me several things. There IS not only a **measurable** “yellowing” of the sun’s light as it passes through the atmosphere, there is a visually OBSERVABLE yellowing. Also, the scattered blue light that caused that yellowing in the first place can be recovered to a significant extent by utilizing the scattered blue light from the sky. Therefore, the sun is both observably yellowed by it passage through the atmosphere AND a white piece of paper (or cloud) exposed to that blue sky and direct sunlight is a MORE accurate representation of sun’s color as seen from space. I knew this from post 2 and its optics 101, but its still nice to get firsthand experimental proof. IMO anybody who can’t see this or disagrees with it doesnt know what the heck they are talking about. ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [February 3, 2010, 8:51am UTC](https://boards.straightdope.com/t/what-color-is-the-sun/527210/47 "2010-02-03T08:51:19Z")
> [@CalMeacham](#): > > Plaitt acknowledges that he can’t say for certain why people think of the sun as yel;low. I guess I know why he is called “The Bad Astronomer” now. Clearly he has never looked up into the sky. ---
**Author:** ![ZenBeam](https://avatars.discourse-cdn.com/v4/letter/z/3ab097/32.png) [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)\ **Post date:** [February 3, 2010, 5:04pm UTC](https://boards.straightdope.com/t/what-color-is-the-sun/527210/48 "2010-02-03T17:04:45Z")
> [@billfish678](#): > > Then there was the thread where I mentioned intensity interferomety and the experts were sure there was no such thing. Then LG butts found exactly what I was talking about and the thread died a quite death. > > I expect chirping crickets here too any minute. I read [that thread](http://boards.straightdope.com/sdmb/showthread.php?t=536309) (and I thought the intensity interferometry thing was interesting), but I don’t see what your problem is with it. ---
**Author:** ![panamajack](https://avatars.discourse-cdn.com/v4/letter/p/47e85d/32.png) [@panamajack](https://boards.straightdope.com/u/panamajack)\ **Post date:** [February 3, 2010, 5:47pm UTC](https://boards.straightdope.com/t/what-color-is-the-sun/527210/49 "2010-02-03T17:47:19Z")
I didn’t mean to imply that the amount of light coming from a sunset to high noon was a significant amount. In fact, I’ll concede that it may as well be nonexistant. The only point I wanted to clarify is that the blue in the sky doesn’t come from light that would otherwise reach you with no atmosphere in the way (to a significant degree.) That the scale of significant scattering is on the order of hundreds of miles, however, is easily demonstrated by the blue skies before and after the sun is visible. ---
**Author:** ![jasg](https://avatars.discourse-cdn.com/v4/letter/j/f0a364/32.png) [@jasg](https://boards.straightdope.com/u/jasg)\ **Post date:** [February 3, 2010, 6:22pm UTC](https://boards.straightdope.com/t/what-color-is-the-sun/527210/50 "2010-02-03T18:22:27Z")
> [@billfish678](#): > > Damn, the guy who said the sun was paisely is ahead of half the herd here. … too much credit. That was an obscure reference to a 40 year old comedy routine about watching the sunrise after an all night LSD trip 😃 ---
**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\ **Post date:** [February 3, 2010, 7:14pm UTC](https://boards.straightdope.com/t/what-color-is-the-sun/527210/51 "2010-02-03T19:14:37Z")
> [@Xema](#): > > The best definition of white light would probably be something along the lines of radiation with equal intensity at all visible wavelengths. No. There are various conflicting definitions of “White” used in photography, etc. Equal intensity is only seldom used as the definition. There’s “NTSC white”, though the actual white displayed may vary from TV to TV or monitor to monitor. There’s an oft-used definition based on mean daylight (I think cloudless noon in Hollywood is the standard 🆒 ) – this would be daylight reflected off white objects, _not_ the color you get pointing camera at sun! In turns of human vision, “white” might best be defined as the color reflected from white walls in the actual ambient light; depending on your incandescent or flourescent lamps, inside “white” might be quite different from outside daylight “white.” Monitor white (i.e. pixel = FF FF FF) is usually much bluer than daylight or inside house light. Working on a computer you may notice the difference as your attention moves betweem computer screen and the rest of the room. ---
**Author:** ![Spectre\_of\_Pithecanthropus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/spectre_of_pithecanthropus/32/12343_2.png) [@Spectre\_of\_Pithecanthropus](https://boards.straightdope.com/u/Spectre_of_Pithecanthropus)\ **Post date:** [February 3, 2010, 7:55pm UTC](https://boards.straightdope.com/t/what-color-is-the-sun/527210/52 "2010-02-03T19:55:41Z")
> [@Chronos](#): > > For a really great example, look at Alberio (the head star of Cygnus, or alternately the base of the Northern Cross if you look at it that way) through a telescope. It’s an optical double, composed of a yellow star and a blue star of just about the same brightness. Or just download this great, free [planetarium](http://www.shatters.net/celestia/index.html) app and find the stars whereof Chronos speaks. It’s not RL, obviously, but it’ll still give you the idea. ---
**Author:** ![Spectre\_of\_Pithecanthropus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/spectre_of_pithecanthropus/32/12343_2.png) [@Spectre\_of\_Pithecanthropus](https://boards.straightdope.com/u/Spectre_of_Pithecanthropus)\ **Post date:** [February 3, 2010, 8:18pm UTC](https://boards.straightdope.com/t/what-color-is-the-sun/527210/53 "2010-02-03T20:18:56Z")
Never mind, having trouble with my Photobucket page. ---
**Author:** ![Spectre\_of\_Pithecanthropus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/spectre_of_pithecanthropus/32/12343_2.png) [@Spectre\_of\_Pithecanthropus](https://boards.straightdope.com/u/Spectre_of_Pithecanthropus)\ **Post date:** [February 3, 2010, 10:10pm UTC](https://boards.straightdope.com/t/what-color-is-the-sun/527210/54 "2010-02-03T22:10:12Z")
Picture of [Albireo](http://s494.photobucket.com/albums/rr308/DeathB4D_Calf/?action=view¤t=Albireo.jpg), from the great, freeware planetarium app Celestia. The two stars at the center, marked Albireo and Beta\*\*2 Cyg form the double star in question, and show a remarkable degree of color contrast. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [February 4, 2010, 12:42am UTC](https://boards.straightdope.com/t/what-color-is-the-sun/527210/55 "2010-02-04T00:42:00Z")
While Celestia is very good, I’d still recommend using a telescope here, since then you know what you’re getting is the real, actual colors. With a photograph, especially a digital photograph, you’ve got multiple levels of color filtering before it gets to your eye: First, there might have been an extended exposure, making the objects effectively brighter and the colors therefore clearer. Then, there was filtering through the color response of your camera’s sensor, then possibly some digital photo manipulation to make it prettier or more informative or whatever, and then filtering in how your screen displays colors, before you finally get to the response of your eye. ---
**Author:** ![Delayed\_Reflex](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/delayed_reflex/32/3172_2.png) [@Delayed\_Reflex](https://boards.straightdope.com/u/Delayed_Reflex)\ **Post date:** [February 4, 2010, 1:22am UTC](https://boards.straightdope.com/t/what-color-is-the-sun/527210/56 "2010-02-04T01:22:20Z")
> [@billfish678](#): > > Some simple experimental results. > > I took my digital camera and took a picture of direct sunlight reflected onto a white piece of paper (but not exposed to the blue of the sky). I then took a picture of the paper out in the yard, exposed to direct sunlight AND the bright blue sky. > > Not surprisingly (to me) the two photos are obviously different. They are different enough that I dont even need to see them side by side to tell the difference. The second photo has a decidedly bluer tint to it. Or, put another way, the first photo has a decidedly yellow tint to it. I can even go in and look at the color histograms and its obvious the second photo has more blue in it. > > That tells me several things. There IS not only a **measurable** “yellowing” of the sun’s light as it passes through the atmosphere, there is a visually OBSERVABLE yellowing. Also, the scattered blue light that caused that yellowing in the first place can be recovered to a significant extent by utilizing the scattered blue light from the sky. > > Therefore, the sun is both observably yellowed by it passage through the atmosphere AND a white piece of paper (or cloud) exposed to that blue sky and direct sunlight is a MORE accurate representation of sun’s color as seen from space. > > I knew this from post 2 and its optics 101, but its still nice to get firsthand experimental proof. IMO anybody who can’t see this or disagrees with it doesnt know what the heck they are talking about. Interesting… but there are some questions as to control factors: -Did you lock the white balance setting on your camera or was it auto-adjust? -What are the ambient lighting conditions inside and could light from inside your house actually be causing the yellower look? -Was this through a glass window, which might have filtering effects? Still, based on your [previous cite](http://www.astro.ufl.edu/~oliver/ast3722/lectures/EffectOfAtmosphere/EffectAtmos.htm) it does appear that there is significant scattering event at zenith. Thus, I don’t think it’s unreasonable to say, if you are calibrating “white light” to mean light from the sun in space, it is “more yellow” after going through the atmosphere even at the zenith. I think what **CalMeacham** was saying though is that the “already yellowed” light that we see from the sun is what we typically calibrate white to. I think he also suggested that there should in fact be no noticeable difference between the whiteness of your paper inside vs. outside, as the direct light from the sun dominates over the blue light from the sky - you seem to think your experiment proves otherwise, but I think you need to make sure you’ve accounted for all other factors before drawing such a conclusion. ---
**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\ **Post date:** [February 6, 2010, 4:12am UTC](https://boards.straightdope.com/t/what-color-is-the-sun/527210/57 "2010-02-06T04:12:18Z")
> [@Delayed\_Reflex](#): > > Interesting… but there are some questions as to control factors: > -Did you lock the white balance setting on your camera or was it auto-adjust? > -What are the ambient lighting conditions inside and could light from inside your house actually be causing the yellower look? > -Was this through a glass window, which might have filtering effects? > > Still, based on your [previous cite](http://www.astro.ufl.edu/~oliver/ast3722/lectures/EffectOfAtmosphere/EffectAtmos.htm) it does appear that there is significant scattering event at zenith. Thus, I don’t think it’s unreasonable to say, if you are calibrating “white light” to mean light from the sun in space, it is “more yellow” after going through the atmosphere even at the zenith. I think what **CalMeacham** was saying though is that the “already yellowed” light that we see from the sun is what we typically calibrate white to. I think he also suggested that there should in fact be no noticeable difference between the whiteness of your paper inside vs. outside, as the direct light from the sun dominates over the blue light from the sky - you seem to think your experiment proves otherwise, but I think you need to make sure you’ve accounted for all other factors before drawing such a conclusion. Bahh… Unless you define white to be when the sun is on the horizon, there are times when the sun is going to be more yellow than the point you’ve decided to call white. And furthermore, for the Nth fracking time, a white cloud under those same conditions is going to be a more accurate representation of the true color of the sun than the sun you can see directly through the atmosphere at that time. Which is what I stated in my first post, the first post to the OP, and was told was wrong. Yes, I locked the white balance. And every thing else I could. There was no glass window. The reflector (first surface aluminized mirror) was likely spectrally neutral to within a few percent (way less than the atmosphere for sure). The scattered “ambient” light was about 1/10,000 (I measured it) of the direct sunlight on the no exposure to bright blue sky direct sunlight only photo. By contrast, the blue scattered component in the exposed to the blue sky and direct sunlight photo was probably somewhere in the ballpark of 10 percent of the total light. Look at the graph on the link I supplied. A decent PERCENTAGE of blue light is scattered, not some trivial amount. Why it would be surprising that you could visually detect that is beyond me. Cal and Chronos were talking out of their rears and got called on it. There is a significant percentage of blue light scattered by the atmosphere which makes the sun appear yellow/yellower. It is certainly not insignificant. There is a good reason the sun is considered yellow. It might be a mild yellow, but it is not imperceptible. And the moment I did the experiment, I could tell the non sky exposed paper had a yellow tint to it. The photo proved it to me, but it was visually obvious the moment I looked at it with my eyes. ---
**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\ **Post date:** [February 6, 2010, 4:31am UTC](https://boards.straightdope.com/t/what-color-is-the-sun/527210/58 "2010-02-06T04:31:25Z")
> [@njtt](#): > > I guess I know why he is called “The Bad Astronomer” now. Clearly he has never looked up into the sky. That reminds me. I need to write him a nasty email too. ---
**Author:** ![foolsguinea](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/foolsguinea/32/14751_2.png) [@foolsguinea](https://boards.straightdope.com/u/foolsguinea)\ **Post date:** [February 6, 2010, 6:12am UTC](https://boards.straightdope.com/t/what-color-is-the-sun/527210/59 "2010-02-06T06:12:41Z")
Looks white to me. Maybe a slight yellow tint in some weather, but come on, it’s putting out a broad spectrum of light! Does Superman lose his powers when the sun is setting & turns red? [Previous page](https://boards.straightdope.com/t/what-color-is-the-sun/527210.md?page=2)