Years I've sat around and watched erroneous Solar color depictions go by -- magazines, books including textbooks, technical articles, diagrams, classification lists, etc. -- but enough is enough!

If you see the Sun misrepresented as being something other than white --as seen from space and not on our terrestrial horrizon -- then post it here (eg. a link). [Don't post the image itself w/o knowing the copyright rules.]

For instance, here is an erroneous montage that is reasonably accurate in planetary colors but isn't remotely close for the Sun. Though the site itself is a spoof in an effort to support Pluto (thanks laurel), it ain't right.

[Please don't post the color depictions of the Sun that are intentionally done in false color for valid scientific reasons. Most of SOHO's images, for example, are presented this way and they state, somewhere, that the images are done in false color. However, there are thousands of other sources that willy-nilly depict the Sun as yellow or some other color.]

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The sun does look yellow to the unaided eye in the Midwest of the United States.

However, here in the desert it is definitely whitish -- only the palest of yellow.

Altitude and humidity factor in I suppose.

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That site is very cute!

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Yes, our atmosphere scatters the blues and greens more than the orange and reds so we observe an altered yellowish or orangish color. But seen from space, without atmospheric extinction effects, it is most definetly white only.

There are numerous threads that address this colorful topic. Here is a blog that should convince those that are more yeller-minded.

Once it is more obvious, then you may begin noticing all the many hundreds of erroneous color errors presented in movies, books, magazines, etc., and it would be nice to have a thread we can post them so we can share in the amusement. This repository may also serve to wake up those that slumber in old traditions, too, so they won't constantly forget making the Sun white when they go to so much effort to get the planet colors right.

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I wanted to start a thread about something similar to what you are saying here, and hope you would have participated. This is even better.

The aquarium trade is full of this one.

The emperor's new clothes was written by aquarium light bulb salesmen.

One company made a perfect fluorescent bulb for the freshwater tank, a company called Aquari-lux. When you looked at the operating bulb directly they were distictly blue with the illusion of a reddish undertone. Over the tank the fish were brilliant and unless you had too big a load of nitrates or were running tannins in your water, the water looked crystal clear.

They were a bit more expensive, so the old boss would carry a range of brands but he wouldn't really hard sell the crappier models. Well, the old boss passed away, as all men must, and the new owner kept falling for anything the salesmen would hand him. This salesmen was a jerk, the old boss having this guy pegged correctly as a salesman, not an expert on lights and bulbs.

I would kill deals by bringing up real world issues, to prevent the new boss from purchasing white elephants we couldn't sell to knowledgable customers, and they would BOTH get mad at me, until said salesman started showing up only on my days off.

I started hating taking days off just because of what I'd find when I got back. (I was working 12 hours a day, four days a week) Imagine my non-surprise to find the new boss purchased a buttload of fluorescent bulbs that "perfectly simulated" sunlight, and put out a warm yellow glow.

I even specifically told the boss not to buy them for the reason stated below. I would make the new boss furious when he would try to push one of this pieces of mistake on an old customer of ours, and I would walk by him in the middle of his speil and say, "Yeah, but it makes the tank look pee'd in." Which it did. The fish looked anemic and it made even a clean tank look like it needed a water change.

Yellow light = crap in an aquarium. This, of course, was my fault. Dispite the fact we were swimming in Aquari-lux bulbs, and these were even more expensive. New boss apparently never played Elite or any or the other trading games.

(He couldn't fire me. He knew I didn't steal, even a little bit, I opened in the morning, and was alone for the first four hours, ran the register, maintained the animals, provided expert customer service, all for mimimum wage. I have a suplimental income from the Navy that allowed me to do this. I actually felt sorry for the new boss. He really wanted to fire me sometimes.)


In the late 80's/early 90's this got really out of hand with the aquarium crowd with the onset of coral husbandry. The zooxanthellae, symbiotic algae (phototrophic dinoflagellates) that reside in the tissues of host corals, are very particular about the light they eat.

That's where I first heard of an "Einstien" or one mole of photons. And PAR Photosynthetic Available Radiation, unit = µE/m2/s between 400 and 700 nanometers. PUR (Photosynthetic Usable Radiation) is more acurate, but that varies with the precise photosynthetic pigments being stimulated))

(Deleted a couple of big paragraghs of coral keeping you don't care about, sorry.)

Yeah, I know about the yellow Sun fallacy.

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I hope you toss in a few more, especially if you stumble across false-colored Suns in web sites.

You would think your boss could see the difference by comparing the color quality of each aquarium. I used to have a 50 gal. salt water aquarium and it was a fair amount of work. I can guess that your customers, like me, were willing to spend a little more to get the "good stuff". This would have enhanced the store's reputation and probably would have generated greater sales and profits.

There is quite a range in bulbs, as you know. My first job was with a hospital in Texarkana and I designed some special light fixtures for the nursery to help the babies with hyperbilirubinemia -- first big real word I ever learnt for good. IIRC, several decades ago, it was a nurse in England that noticed that jaundiced babies that happened to encounter sunlight were healing quickly. [Sunlight causes a production of vitamin D, I think, in the skin, which helped these babies.]

Of course, the right bulbs would be required and those simulating sunlight would likely be the best. You would think the CRI rating would be the best indicator but that is not so since an incandescent bulb (color temp. of ~2800K or less) has a 100% CRI by definition. A 5000K bulb, however, is better even at a lower CRI.

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Hmm... well, in my room there are two solar systems on display. One I made myself, with a standard glow star for the sun, so it's sort of green, the other is a poster where the sun looks red-orange like some of those SOHO images taken through the red filters.

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I want to go back to the moon.
I don't care which rocket you use, whichever one you pick, I'll like it, I swear.
"If you think the LHC will create black holes, you might as well believe Hobbits are at the bottom of your garden."- Dr. Mike Inglis
Rovers forever! - ToSeek

Yep. While you're at it, take a look at Venus in your display and tell me if it isn't yellow filaments on an orange background. Often, not only is the Sun completely wrong but they use the radar imaging of the surface of Venus for their depiction of how it appears in space. Ha! [There are a few new ones that are using a more milky yellow color for the cloud cover of Venus, which is probably correct. Only one person have I found that has done work on this.]

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I have heard our sun referred to as a "yellow dwarf star." Is that term incorrect, and if so, what is the correct classification? I know it cannot be a "white dwarf star," as that is the term used for a dead star after it has gone through its red giant phase.

Yep! And you thought the Pluto polemic was big! I don't think I've seen any color reference used for the Sun other than yellow when this adjective is used as part of the Sun's "official" classification.

Now you are seeing just how much fun this topic can be. How they gonna fix this problem? Renaming it a white dwarf isn't going to go over that well, is it? Of course, we could just wait 4 billion years and then rename it when it becomes a white dwarf.

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Since this is a repository....

Here is a nice NASA web page discussing the Sun. It has three images of the Sun and these colors are, respectively: red, orange, yellowish-orange. No white, as usual.

That is not quite correct. The blue end of the spectrum (violet, blue, cyan, or 400nm to 510nm) is ~ 8% greater than the yellow green portion (510nm to 590nm). [see below attachment.] Yet, more importantly, is the conversion of this spectral energy distribution (SED) to photon flux, since our eyes respond to photons, which flattens the SED.

Ooh, they hit the nail on the head, but they failed to drive it in.

Hmmm... that doesn't seem to "eschew obfuscation".

They were close, but muffed it.

Attached Images

Thuilier Flux Compar.jpg (103.8 KB, 13 views)

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Here is a very nice 3D model of the nearest star systems relative to, uh, the yellow Sun.

And they give the classification of each star system, including ours:

If they don't even know the color of their own star, how can we be sure they can claim only eight planets orbit it? [That one's for you, laurele. ]

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Most astronomy and astrophysics texts will call the sun a "yellow dwarf". It is a dwarf because the classes are "dwarf" and "giant" and only huge stars can be giants. Yellow is close to the peak frequency (it's actually green) and "green dwarf" just doesn't work.

I guess a question is, if the sun were far enough away to appear to be the brightness of one of the several yellow stars in the sky (e.g. Capella), would it look similar in color to Capella.

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Todd (Bowie, MD, US, North America, Earth, Sol System, Vega region, Local Bubble, Orion arm, Milky Way Galaxy, Local Group, Virgo A Cluster, Virgo supercluster, the universe in which spock is clean shaven)

Quidquid latine dictum sit, altum sonatur.

personal page: http://blog.astrosketches.info

White is such a boring color. I'm going to load up a huge spaceship full of mellow orange dye and launch it into old Sol.

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There in the valley of Scorpio, beneath the Cross of jade
Smoking on the seashell pipe the gypsies had made
We sat and we dreamed a while...in that crystal thought time in Mexico. ~Donovan

According to your photon flux graph and claim that that is what matters to visual perception, sunlight should be redder than white. The graph is basically flat from 500nm to 735nm but drops off considerably blueward of 500nm.

And where do you find this erroneous information, one may ask? Just look at the data. The Wehrli '85 peak is at 481.5 (blue) at 2092 w/m²-nm. The SOLAR 2000 (NOAA) also shows 481.5 at 2088 w/m²-nm. SORCE has sp. irr. data almost daily and it is closer to 450nm, IIRC. [These peaks are more like pimples so their variation does not change much.] But, it ain't green, or yellow, or green yellow.

Ah, but that is a binary, which alters how we see the lower temperature star. Capella is also a little cooler, 4900K, but the binary neighbor is about 5400K. This hotter neighbor, I think, will trigger the brain to see it as the white reference and cause Capella to look a little yellowish. Is this your experience.

This physchological effect is part of a "color constancy" aspect of the retinex (retina + cortex) processing. Our brains like to make reference light white. For example, car lights look white at night, but yellow during the day (due to the new reference light -- the white Sun).

The "true color" of the Sun is based on what color we would see it if we could see it from space and at an attenuation level that is comfortable for our photopic (color) vision.

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Good point. The problem is I dont know what photon flux distribution can best define white for our color viewing brain. Evolution may have tweaked it to be simply what the Sun radiates, which the photon flux curve above demonstrates. To my limited knowledge, no studies have been conducted to determine a better white. [I haven't checked the Tide soap website, admitedly. ]

It would be difficult to conduct such a study due to the color constancy capability of our brain (and color processing cameras, for that matter).

Ultimately, some astronaut will go up with a SAD (Solar Attenuation Device) and give us the SAD result -- it ain't got no color.

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The adaptation argument doesn't support the Sun is white, unless you're talking about the Sun as seen at the top of the atmosphere. Our eyes aren't adapted for looking at the Sun, they're adapted for looking at things relatively close in the ambient (African) daylight. That ambient light is typically a combination of direct sunlight and the bluer sky light. If the sum of these is white then the perceived color of direct sunlight should be redder than white. If it is more important to see things such as predators in shadows, then our eyes will be further adapted to the blue. Of course part of the time it is cloudy, but according to wikipedia the light under an overcast sky should have almost the same spectrum as a cloudless day, only dimmer.

There are certainly some differences in the spectral distribution given a number of circumstances. Terrestrial Solar altitude, for instance, is very important to the resulting SED due to atmospheric scattering. The greater extinctions of the blue end varies somewhat as to the cosine of the altitude. The Sun's disk doesn't become yellow until relatively near the horizon. The extinctions across the entire spectrum, though more so on the blue end, can be so great under dusty conditions that binoculars can be safely used to observe the disk, but only if the disk is easy on the eye without the binocs, of course. It is worth warning any reader not to do this unless it is obviously safe. [CORRECTION: IR is likely too strong to use binoculars safely, so don't do it.]

I would doubt that a blue sky would do much to reconstitute the resulting spectrum of the remaining balance of direct sunlight, but it would contribute at least some blue light back into the mix.

Perhaps the spectral irradiance of an AM2 sunlight beam with a blue sky would be a perfect white. My guess is that the range of a perfect white would be quite broad across the spectrum.

But there are limits to this range of white. For instance, since you mentioned light in shadows, place a white sheet of paper in a large shaded region but with blue sky illuminating it. The paper will have an obvious bluish-white appearnce (though certainly not as blue as the sky).

This broad white zone, if we want to call it, is all the more reason the Sun is a white object, though blindingly brilliant.

That makes sense since clouds exhibit Mie scattering, which is uniform across the spectrum.

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One is milky, the other is kind of golden with brown spots.

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I want to go back to the moon.
I don't care which rocket you use, whichever one you pick, I'll like it, I swear.
"If you think the LHC will create black holes, you might as well believe Hobbits are at the bottom of your garden."- Dr. Mike Inglis
Rovers forever! - ToSeek

Does the latter look like this?

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Kinda. It's probably a radar image. One out of two isn't bad.

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I want to go back to the moon.
I don't care which rocket you use, whichever one you pick, I'll like it, I swear.
"If you think the LHC will create black holes, you might as well believe Hobbits are at the bottom of your garden."- Dr. Mike Inglis
Rovers forever! - ToSeek

Better than average.

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Ask an astrophysicist says the Sun is a yellow star.

[I bet no one invites me to their next IAU meeting. ]

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And here we go again: http://www.suntrek.org/sun-as-a-star...lour-sun.shtml

As a kid, I always had a neon bulb in my room that was labeled "daylight", so I suppose it should imitate "daylight", i.e. a black body at the sun's temperature.
Compared to all other rooms with incandescent bulbs or "soft" tones, my room always looked very bluish from the outside - but of course was pure white

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Mars Society.

Ah yes, I recall that one. That's a doozie. The Suntrek team appears to consist of some SOHO scientists, too.

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Here is an elaborate web site (foreign) on stars, though not from a professional astronomer, apparently.

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NASA Goddard Space Flight Center makes mention of a yellow Sun.

Am I a pest, or what?

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The official technical classification would be G2V.

Yes, but is there an "official classification" by the IAU or some other "official" body?

What strikes me is how often "yellow dwarf" comes across as being an official part of the classification, though I suspect it is not, which is why I haven't addressed it. But now that you have (sin of omission )...

There are ~ 1100 sites that pop-up in Google using " Sun G2 'yellow dwarf' ". Some of these are from some big guns, including SOHO and some Physics courses.

I think will all change in time, of course, as this pimple of a blemish is raising its head, so to speak. [Too bad we don't have some white emotioncons. ]

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