The mid-day sun is obviously not yellow. What the article says is
As soon as the sun is attenuated enough to look at even fleetingly, it appears yellow, and it remains this way until it rapidly begins to change color at sunset.
I think this is what you’re missing. The paper says " However, the Sun is essentially all colors mixed together, which appear to our eyes as white . This is easy to see in pictures taken from space.". But you’re saying “the Sun is pretty yellow when viewed from Earth.”.
It’s like trying to argue that the light coming from a lamp is actually orange because when you sit on your couch and look at the light coming through the lampshade, that’s what color you see.
You’re all wrong and talk past each other. The great physicist Bob Dylan (hey, he’s got a Nobel) stated already in 1966:
The sun’s not yellow, it’s chicken.
Of course that is the definitive answer.
In the Stanford article cited by the OP, it begins by saying that children often draw the sun as yellow, and then leads straight into saying that it’s actually a misconception that the sun is yellow.
But of course there is no inaccuracy or misconception there; they are drawing the sun as we see it just like they are drawing everything else as we see everything else.
That’s why this whole tangent of the sun being “really” white is just delighting in knowing a thing and correcting people and ignoring all context and practical detail.
If someone were to draw the solar system and show the sun as yellow, then, in that context, it might be worth pointing out that the sun is really white, but even there, most astronomical institutions give the sun a yellowish hue in such representations, because they often want to show flares and other details.
To what extent is that true, versus them drawing it that way because that’s the way they’ve seen others draw it? Children’s drawings often aren’t accurate in many ways: For instance, they’ll often draw blue sky at the top of the page, and green grass at the bottom, but leave the middle of the page blank.
I don’t know, it’s hard to separate out the effect of culture. But the point is, it’s not an emperor’s clothes kind of thing; when children are able to look towards the sun, it’s yellow.
Right, and we don’t make a big deal about correcting such things. Which further emphasizes that “The sun is really white” is a popular meme / factoid right now, not something that is necessary to point out or that we’re being consistent about.
Like many(?) children, you can look at the sun using a couple of pieces of paper or foil to make a pinhole camera; then you can judge for yourself (make sure you project it onto a white piece of paper, though!)
You made my day!
And how do you define whiteness in paper? Circularly!
If that were the criterion, then I’d expect children to draw a red Sun. The times when we’re most likely to look straight (or almost straight) into the Sun for more than a moment are sunrises and sunsets - and then its colour is more red than yellow. I suspect there is a strong cultural conditioning behind the mental image of a yellow Sun.
Don’t kids draw the sun as yellow because you can’t really draw it as white with a typical crayon set and white paper? They also draw lines coming from it to represent it shining. It’s more of an icon than an accurate representation of what one sees.
However, those same kids can see that the sun becomes more yellow as it goes up higher, before it becomes too bright to see. And they are likely aware of the concept of the sunset/sunrise, where the sky changes from its “real” blue color to orange-ish. So it makes sense that they think the sun is “really” yellow but changes color at sunset/sunrise.
I do agree that cultural conditioning is part of it. However, that cultural assumption came from somewhere, and I suspect the above is the explanation for that, even if it was an adult who originally noticed and not a kid.
Another thing I’ve not seen mentioned in this thread that reinforces the cultural assumption is the fact that the sun is scientifically classified as a yellow star (a yellow dwarf, specifically). This can’t be the origin of the cultural assumption, as that origin predates the idea of stellar colors. But it probably does help reinforce the idea.
I’ve definitely heard the idea that the sun is “actually” yellow, but appears white to us because it’s just so bright, and overloads all our color receptors. I very much suspect this is based on the idea of the sun being a yellow star.
Another argument that I can see is that in many ancient civilisations, gold was associated with the Sun and the personified Sun god. But since gold comes in many different shades, depending on the other metals it can be in an alloy with, I wouldn’t regard that as conclusive evidence that the “natural” colour of the Sun, as it would be perceived by a a hypothetical person who is entirely free of any cultural preconditioning, is yellow.
First read-through I thought you said Vegas. Lots and lots of light pollution?
I’m not sure that I would agree with that actually. I can’t remember the last time I saw a classic red sunset, it can’t occupy a long portion of the day.
The point is, the natural color of the sun for a hypothetical person who is entirely free of any cultural preconditioning is: it varies, based on time of day, the season and the weather.
You would need culture, including science, to tell you that white is the pure color and the others are the result of atmospheric scattering.
I’ve been reading about astromomy and the stars for most of my life, and “yellow” was always the color used to describe Type G stars like the sun. Obviously the sun hasn’t physically changed from yellow to white since I first heard of the Hertzsprung-Russell classifications, so is this just a change in terminology? Did the people who decide these things come to the conclusion that Type G stars are really more white than they are yellow?
As for what color the sun appears to be in our sky, who can really look at it like that, anyway? Glancing at it for a fraction of a split second, all I see is glare which actually looks a little bluish.
Again, the problem with talking about white is that there is no such colour. Indeed talking about most colours is fraught. Colours are an artefact of the human eye, and don’t have all that much to do with actual physical characteristics of things. The problem being that the eye is a very coarse and inexact device, and sees that same colour with an infinite range of different stimuli. There is no one to one correspondence between a perceived colour and a mix of wavelengths of light. This is true of what the eye perceives as white. Given we evolved on the Earth, and evolved before we invented even fire as an artificial light source, it is no surprise that we perceive daylight as a neutral illuminant. That is something with no colour, and hence white. Daylight is not just the direct sun, but includes illumination from the sky, and thus tends to have additional shorter, bluer, components.
When we talk of colour temperature, we are talking about black body radiation. Our sun is 5772 K, which is perceived by our eye as having a blueish cast. There are plenty of much hotter and much colder stars, and you only need to look into the night sky to see the variations. These are just black body radiators, and you are perceiving a very limited range of wavelengths snipped from the overall spectrum of light emitted. I suspect that astronomers creating the star classifications found themselves with an annoying problem. Whist stars on the main sequence run from say 2200K up to 50,000K, which provides an easy run from red to blue, they did not want to transit through white, as that isn’t a colour. So they transit from red to yellow to blue, and conveniently avoid having any star on the sequence described as white. If they did allow white, they would make G2 stars white. Which is our sun. But if you disallow white as a colour, our sun remains yellow. It could have been pale blue. But people would just call them nuts if they did that.
Some kids do. It’s based on the cultural icon in use. In a page linked from the OP page, it says kids in Japan draw the sun red.
The daytime sun is white. It is, in fact, our very definition of white.
Yet virtually every culture on earth depicts the sun as yellow, or describes it that way. How can this be?
The answer is that if you look at noontime sun, which can only be done fleetingly, it really is white. The only time you can get a good look at the sun is when it is lower in the sky, and at that time the sun does appear to be yellowish, because as the sun gets lower in the sky more blue light gets scattered out.
When the sun is near the zenith there is, of course, some scattering – but not enough to meaningfully affect the sun’s apparent color. As the sun sinks lower ion the sky its rays pass through a greater length of atmosphere, and more scattering occurs. Rayleigh scattering famously varies as the inverse fourth power of the wavelength, so blue light is preferentially scattered out and the redder wavelengths are preferentially transmitted. And because that fourth power is so great, it doesn’t take a huge change in atmospheric path length to make the color change further.
In late afternoon the sun can be glimpsed more easily than at zenith (partly because light has been scattered out), and it looks yellow. That’s why Lewis Carroll could write about Alice in wonderland taking place on “a golden afternoon”. As the sun gets lower, more short wavelength light gets scattered out and the sun turns orange, and finally red. (The amount of scattering also depends upon what’s in the air, its temperature, and humidity. So sometimes the sun appears to be no more than yellow when it’s on the horizon)
The reddening of the sun as it sinks is the flip side of the sky being blue. Rayleigh scattering explains not only why sunlight passing through the atmosphere is on the red side, it also explains why the light scattered from the sky is blue – that inverse fourth power makes the blue wavelengths dominant. So it’s true that the sun appesars yellow and the sky blue because of scattering. But the sun doesn’t look yellow by contrast with the blue sky – it really IS yellow. You can verify this with spectroscopic measurement.
In fact, one of the standard exercises is color science is to derive the color of the sky light from the inverse fourth law of scattering. You can use tristimulus color calculations to obtain the bluish color. I’ve also worked the same problem for the transmitted sunlight, plotting the CIE chromaticity coordinates of the color of the sun as it passes through thicker and thicker layers of atmosphere. You can see it proceed from the center white position, moving down the yellow color locus , then veering off and asymptotically approaching the spectral locus as it moves through yellow to orange to red to deep red.
Star color is determined by the surface temperature they attain. The giants are blue; then next is white, then yellow and then, finally, red when they reach old age and begin to expand.
Star color is essentially determined by blackbody radiation – stars are approximated pretty well by blackbodies. You can get the equivalent color of a blackbody using those rules of colorimetry I described in my post. The color of a blackbody as a function of temperature was calculated long ago and plotted on a CIE chromaticity diagram, and is called the Planckian Locus . So the color of different types of stars are given by points on that curve
Our sun is 5770 K. Here’s a plot of the Plankian locus with temperatures marked. You can see that our sun is at the white “center” point:
