Newsweek fact checks Sun's color

[Helio]

Newsweek has jumped into a Twitter discussion to present their fact check view. Here

The common errors still go ignored, so perhaps someday osmosis will creep over them and overtake these careless errors. Perhaps my fact check of their fact check will help....

Color is subjective. The way human eyes have evolved to see color means humans see things that might appear to be completely different in color to an animal, whose eyes are set up differently.

The Sun's color is a human question, not an animal kingdom question. Some colors are more subjective than others. Some see a number of red dwarfs as red and some will argue that they are orange. So there is some level of subjectivity with color, but many colors are more objective than otherwise. Is not a red apple red?

It's also true that some colors of light from the sun are more energetic than others. Most of the energy that the sun radiates is in the part of the light spectrum that we would perceive as green, for example.

This is bunk, but not an uncommon factoid. Their green argument link goes to the color of plants (green). Ug. I have posted many times the actual spectral irradiance of the Sun, seen from space telescopes, that demonstrably establish that the Sun's greatest emission color is blue, not green. [I'll post it again if anyone wants to see it.]

But speaking purely in terms of how humans see the sun, it would be accurate to say that the sun's color is indeed white.

Always nice to see the end result be extremely likely correct.

The reason sunsets and sunrises appear red, yellow, or orange is because when the sun is lower in the sky its light must travel through more of Earth's atmosphere to reach the ground than when the sun is directly overhead.

The longer it takes for sunlight to travel through the atmosphere, the more shorter wavelengths of light—such as blue—will be scattered, while longer wavelengths—namely red—can continue for much longer distances. So the reason sunsets and sunrises appear red is because there is more red light left for us to see by the time the sunlight reaches our eyes.

Yes, and the Sun almost never appears red, but unusually high particle counts can make this happen, which happens during forest fires, for instance.

Outside of the scattering influence of our atmosphere, astronauts agree that sunlight looks white. "I can confirm this space fact," tweeted former NASA astronaut and International Space Station commander Scott Kelly in response to the Latest In Space tweet claiming the sun is white.

This may be an accurate assessment, but the Sun is even brighter in space than it is from below our atmosphere. It is so bright that if the Sun were, say, yellowish-white, an astronaut that did not have proper neutral attenuation would be overpowered with sunlight causing a white result. Astronaut Don Petit had hoped to do a pinhole experiment aboard the ISS, but he never go the time to do it. I doubt any experiment has been done properly, IMO.

When all colors are mixed together, they appear white to human eyes.

Bunk^2! Since red stars, for instance, emit all the visible colors, are red stars white? Blue stars do the same, are they white?

Color determination is a function of not only the color but the respective intensity of each color. Also, the lighting industry produce light bulbs that shine white without the emission of all the colors.

Proof that sunlight is many different colors of light mixed together is in rainbows. Similar effect can be achieved with a prism.

Rainbows and solar spectrums will quickly reveal that the balance of the colors is uneven.

Here is perhaps the best of all solar spectrums, taken at the McMath-Pierce solar observatory at Kitt Peak. Notice how the color bands are not at all equal. Yellow is the smallest.

The sun is indeed classed as a yellow dwarf star, but this is a misnomer—it does not mean the sun looks yellow to us. The name simply refers to the sun's medium size, common for this class of stars.

Correct, but these early classifications implied that the stars exhibited the color of their assigned class.

IMO, this goes back to the earliest days of spectroscopy (late 1800s). Father Secchi is the grandfather of stellar classifications after detailing the spectrum of over 4000 stars. He noticed that the solar spectrum seemed to match the star Capella, known to appear yellowish. So I believe that the Sun got tossed into this class. The important point is that these are spectral classifications that tell a ton more about a star than its color, so it isn't all that wrong to put the Sun in the yellow class. Nevertheless, it would be nice to fix this color conundrum. We can't call it a white dwarf, so this solution is far from easy.

When considered from the perspective of a human, and eliminating the scattering effect of Earth's atmosphere, sunlight is white.

Well, all you have to do is conduct a simple pin-hole experiment. Even a noon-day Sun will appear white, with no yellow.

 

[Catastrophe]

Helio, there is something in "All About Space", Issue 131 (Current), that you might like to respond to. The cover announces "20 Universe Myths Busted", so No. 3 is a myth, and reads " "3 The Sun is Yellow". The relevant part reads as follows, and the rest is about Sun appearing red at sunset, and the like. I will send you a scan by email, including response details, if you want to respond.

Though you should never look directly at the Sun, photographs reveal a yellowish hue. The Sun produces all wavelengths of visible light, and therefore the true colour is white, but as sunlight travels through the atmosphere it changes . . . . . . . . . .

Cat

 

[Helio]

I believe these “myth busters” are just a little lazy because they likely know red and blue stars emit all the colors.

This may also be regurgitation since, like Newsweek, this error is a bit ubiquitous.

I don’t recommend anyone should eat their cooking, since cooking is more about how much of each ingredient goes into cooking than which ingredients are used. Who would make a Scotch Pie with 50% lard? This is why we follow recipes, not just a list of ingredients.

 

[Catastrophe]

Helio, I just wondered whether you wanted the opportunity to express your views in a major journal. (Following our correspondence of a while ago).

Cat

 

[Helio]

Yes, please send that to me. [I was on my phone earlier.]

[Added: I found the publication, but it requires purchase. So, if you do have the response email, I will follow-up.]

Thanks.

George

 

[Catastrophe]

OK see email. Scan and info sent. Cat