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George
2005-Feb-21, 03:24 AM
...not known, yet. :-?

Warning: Physicists are not allowed to read further! (reasons stated below)

If you do happen to know, with substantiation, the true extraterrestrial color of the sun, after it's intensity has been attenuated to a normal flux for our eyes, I will be most appreciative if you share this important knowledge. I could then stop my troublesome quest.

Abstraction:
This is a very complex subject of enormous triviality, yet, possibly, warm and tender for the hearts of all mankind. “Complex” because it is a mystery why it is a mystery. The Sun's color is fairly easy to obtain - reproduce it's visible spectrum (@AM0), and you got it . (Yet, this is not as easy as I hoped it would be. :x )

I have not found much in astronomy regarding prior efforts or even a prior a priori oratory. (I know ‘cause I have spent dozens of minutes googling.) From his book, the BA has clarified nicely the color which the sun is not - yellow. But the begging question (now a serious itch) remains - "what color is it really?".

The Sun's color is also complex in the sense one can easily say that this subject is clearly over the heads of most astronomers and physicists. This statement can not be said very often, obviously. Considering the consistency of the subject being over their heads, around noontime everyday, you would think they would consider it with greater interest. Perhaps they are.

Maybe additional complexity is inherent in the sociological/psychological aspects of this topic. Let’s say I’m an astronomer. Hmmmm, ok, let’s say you’re an astronomer. You were on the neutrino team arguing with physicists about the neutrino problem. You help show that they have mass and the single-flavored nuclear core neutrinos emissions turn into all three flavors. Thus, the massless neutrinos now have mass and the 1/3 issue is resolved. You finally have the physicists on their heels at a major luncheon. You summarize the winning arguments on the issue and you sense the sea of accolades rising before you because of your proven mastery of the Sun. Just as you have the servers place the main entre (crow) on the physicists table, one physicists stands-up in the crowd and demands - “but can you tell us the color of the Sun?”. Yeowww!

Therefore, I hope to discover this knowledge and pass it to the folks I greatly admire - astronomers. (Be clear, I admire physicsts also) Thus, saving them from the horrible and inevitable fate illustrated above. Naturally, this should be done under the table so as to not cause disgust among physicists once they have discovered their lost opportunity to cast anguish upon our noble and stellar scientists.

The following is limited information on the solar determination device as it makes light of the experiment itself. However, I can share some things. Since the solar irradiance is known both above our atmosphere (extraterrestrial) and from our surface (terrestrial), a template can be made to reproduce the sun’s visible spectrum as the eye would behold it in space. Of course, the intensity of the light must be attenuated to allow the eye to “see” the color.

Procedure 1: Gain familiarity with prism and lenses.
Equipment 1: F2 prism and large double convex lens.
Result 1: My pants caught on fire. While recombining the colors through the double convex lens, I failed to consider the sunlight which was also passing through the lens. [who knew it would handle both?]. I noticed an alarming amount of smoke coming off my blue geans. I did not need to notify OSHA of this incident as it was minor. Also, my jeans will be a little cooler come summer.

I failed in getting my nice ebay prisms calibrated. However, new calibrated prisms have arrived.
With some help from A Hundred Pardons (real name being withheld till I have his approval), I have interpolated the prism’s index of refraction for each appropriate wavelength. This will allow sunlight color dispersion to align with the template properly.

Wish me luck.

Project name suggestions welcome. Funding is private but exceeds the S.A.D. experiment.

Eroica, prepare for trepidations.

[Many delays are likely, in fact, my son is buggin me to play ping-pong]

:lol:

Candy
2005-Feb-21, 04:03 AM
With some help from A Hundred Pardons (real name being withheld till I have his approval), I have interpolated the prism’s index of refraction for each appropriate wavelength. This will allow sunlight color dispersion to align with the template properly.
I wonder who it could be. :-k

George
2005-Feb-21, 04:52 AM
With some help from A Hundred Pardons (real name being withheld till I have his approval), I have interpolated the prism’s index of refraction for each appropriate wavelength. This will allow sunlight color dispersion to align with the template properly.
I wonder who it could be. :-k

I suppose we could conduct a contest? Well, maybe not. :)

[edit: method test... here (http://www.badastronomy.com/phpBB/viewtopic.php?p=357089&highlight=sun+color#357089)

switchtech
2005-May-04, 05:21 AM
I think a lot of the color perceived is subjective and influenced by the wiring of the brain. I've always perceived the Sun's disk as very nearly white. Certainly any projected image of the Sun (as with a pin hole "camera" for solar eclipses) appears white. The only time I do not see it as white is near the horizon where it first takes on a yellow, then orange, and finally red hue (it doesn't always make it to red, depending, I suppose, on the amount of dust in the air).

My thought, then, is that our memory of seeing the Sun near the horizon affects our remembered perception of the sun. Other factors such as the amount of blue scattered, the sensitivity of our eyes at different wavelengths and experience with other sources of light, such as candles also influence our perception.

Of course I may suffer from some small amount of color blindness (when I entered the military many aeons ago I had to take a color perception test and missed one of the 20 or so figures). So my perception of the whiteness may be influenced by that, too.

Why do children color the sun yellow? That's what color adults tell them the sun is, and white on a white paper doesn't show up well. (Notice, please, that children often draw people with purple or other unusual colored crayons).

Just my nickle's worth.

TriangleMan
2005-May-04, 11:16 AM
I think a lot of the color perceived is subjective and influenced by the wiring of the brain.
Welcome to the board switchtech. This is a key issue in Psychology studies involving perception. It comes down to psychologists currently lacking the means of determining if two people perceive the exact same colour when they look at an object. I don't have any links but if you do a Google search for this issue you may find a lot of discussion in Psychology journals about it.

ToSeek
2005-May-04, 02:19 PM
There are people on GLP who will swear to you that the Sun has turned from yellow to white in their lifetimes.

A Thousand Pardons
2005-May-04, 03:20 PM
It comes down to psychologists currently lacking the means of determining if two people perceive the exact same colour when they look at an object. I don't have any links but if you do a Google search for this issue you may find a lot of discussion in Psychology journals about it.
No, it's been determined. They do not. :)

How do I know? Because even one person (me) doesn't perceive the same thing each time--here's the Checker Shadow Illusion (http://web.mit.edu/persci/people/adelson/checkershadow_illusion.html) created by Ed Adelson (http://web.mit.edu/persci/people/adelson/index.html). No way do squares A and B look the same to me!

And it's easy to prove that they are. Just copy the image into a paint program, and drag one box over next to the other. They are identical.

Lance
2005-May-04, 04:20 PM
There are people on GLP who will swear to you that the Sun has turned from yellow to white in their lifetimes.

Maybe the chemtrails cause the color change.

ToSeek
2005-May-04, 05:02 PM
There are people on GLP who will swear to you that the Sun has turned from yellow to white in their lifetimes.

Maybe the chemtrails cause the color change.

Somebody's spent way too much time at GLP lately.... :D

But I'll have to suggest that the next time the subject comes up.

Lance
2005-May-04, 06:37 PM
Somebody's spent way too much time at GLP lately.... :D

I wish someone would beat me with a stick and drag me out of there.

George
2005-May-05, 12:43 PM
Welcome aboard, switchtech! =D>

This is a fun topic.

Here are a couple of other threads you might enjoy..... here (http://www.badastronomy.com/phpBB/viewtopic.php?t=8123) and also here (http://www.badastronomy.com/phpBB/viewtopic.php?p=445050&#445050).

George
2005-May-05, 12:51 PM
...even one person (me) doesn't perceive the same thing each time--here's the Checker Shadow Illusion (http://web.mit.edu/persci/people/adelson/checkershadow_illusion.html) created by Ed Adelson (http://web.mit.edu/persci/people/adelson/index.html). No way do squares A and B look the same to me!

I don't recall a better example. Thanks. =D>

Do you have any illusion illustrations dealing with colors?

A Thousand Pardons
2005-May-05, 05:16 PM
...even one person (me) doesn't perceive the same thing each time--here's the Checker Shadow Illusion (http://web.mit.edu/persci/people/adelson/checkershadow_illusion.html) created by Ed Adelson (http://web.mit.edu/persci/people/adelson/index.html). No way do squares A and B look the same to me!

I don't recall a better example. Thanks. =D>

Do you have any illusion illustrations dealing with colors?
Do you mean, similar to that one, where a square of one color is different from another square? I tinted that illustration, and it still worked--but I assume you mean not just different tints.

I don't see why it wouldn't work.

Candy
2005-May-05, 05:29 PM
Do you mean, similar to that one, where a square of one color is different from another square? I tinted that illustration, and it still worked--but I assume you mean not just different tints.

I don't see why it wouldn't work.
I still don't buy it. The photo's tint on the first page is not quite the same tint on the second page.

A Thousand Pardons
2005-May-05, 05:35 PM
Do you mean, similar to that one, where a square of one color is different from another square? I tinted that illustration, and it still worked--but I assume you mean not just different tints.

I don't see why it wouldn't work.
I still don't buy it. The photo's tint on the first page is not quite the same tint on the second page.
We may be talking about two different things. I think there's only one page (http://web.mit.edu/persci/people/adelson/checkershadow_illusion.html). :)

Candy
2005-May-05, 05:46 PM
Do you mean, similar to that one, where a square of one color is different from another square? I tinted that illustration, and it still worked--but I assume you mean not just different tints.

I don't see why it wouldn't work.
I still don't buy it. The photo's tint on the first page is not quite the same tint on the second page.
We may be talking about two different things. I think there's only one page (http://web.mit.edu/persci/people/adelson/checkershadow_illusion.html). :)
What's this page (http://web.mit.edu/persci/people/adelson/checker_more_evidence.html), then (from my computer's history)? Are you messing with me? 8-[

A Thousand Pardons
2005-May-05, 05:57 PM
Do you mean, similar to that one, where a square of one color is different from another square? I tinted that illustration, and it still worked--but I assume you mean not just different tints.

I don't see why it wouldn't work.
I still don't buy it. The photo's tint on the first page is not quite the same tint on the second page.
We may be talking about two different things. I think there's only one page (http://web.mit.edu/persci/people/adelson/checkershadow_illusion.html). :)
What's this page (http://web.mit.edu/persci/people/adelson/checker_more_evidence.html), then (from my computer's history)? Are you messing with me? 8-[
Moi? Appears to be the page that you get from clicking on the "proof" link on the first page, and then the "more evidence" link.

Are you saying the square A and the square B are actually different at the first page?

Candy
2005-May-05, 06:18 PM
http://home.att.net/~candy.stair/TINT.jpg

You don't think the "proof" is a little tainted on the explanation page? Are you not seeing this on the explanation page? 8-[

edited

A Thousand Pardons
2005-May-05, 06:26 PM
You don't think the "proof" is a little tainted on the explanation page? Are you not seeing this on the explanation page?
I never looked at the explanation page :)

I used a different method (http://www.badastronomy.com/phpBB/viewtopic.php?p=465632#465632) of proving it. Try one! they work.

Candy
2005-May-05, 06:30 PM
And it's easy to prove that they are. Just copy the image into a paint program, and drag one box over next to the other. They are identical.
I saw what you wrote, but I can't see what you see. :wink:

A Thousand Pardons
2005-May-05, 06:40 PM
Try this (http://www.pctechbytes.com/) :)

Candy
2005-May-05, 06:45 PM
Try this (http://www.pctechbytes.com/) :)
Don't make me post your photo? [-X

:lol:

A Thousand Pardons
2005-May-05, 06:47 PM
What? was that you?

Candy
2005-May-05, 06:51 PM
How about this? I'll be both shades of A & B, and you just be the square. :lol:

A Thousand Pardons
2005-May-05, 06:52 PM
I'll be both shades of A & B
? but there's only one

wait, let me think about this

Candy
2005-May-05, 06:54 PM
I'll be both shades of A & B
? but there's only one

wait, let me think about this
Yeah, using this! 8) <---meaning shade(s)

George
2005-May-05, 07:01 PM
Do you have any illusion illustrations dealing with colors?
Do you mean, similar to that one, where a square of one color is different from another square? I tinted that illustration, and it still worked--but I assume you mean not just different tints.

I don't see why it wouldn't work.

I saw a color cube illustration combined with something in the background. The squares looked one color but changed their color when the cube was moved to a different color background, I think. Contrasting colors emphasize certain colors more than others. Your B&W example reminded me of it.

mickal555
2005-May-19, 10:46 AM
Is this the massive discussion?

George
2005-May-19, 11:50 AM
Is this the massive discussion?

It suppose to be just colorful. :)

Edit....
The more massive one is in GA.... Sun's Intrinsic Color (http://www.badastronomy.com/phpBB/viewtopic.php?p=445050&#445050)

Also, on this forum is another related thread..... here (http://www.badastronomy.com/phpBB/viewtopic.php?t=8123)

suntrack2
2005-Nov-04, 08:23 AM
the sun rays has no specific colour, it means is it possible that sun has no colour as we are looking from earth. in one book it was written before 400 years that sun rays are colourless, when they reach through the different spheres then the rays we found colourful.

George
2005-Nov-05, 04:34 AM
the sun rays has no specific colour, it means is it possible that sun has no colour as we are looking from earth. in one book it was written before 400 years that sun rays are colourless, when they reach through the different spheres then the rays we found colourful.
Prior to Newton, this might be true. I would enjoy learning the various ideas of how color was "seen" prior to his discovery that white light is combined colors.

Our atmosphere takes out some of the red light and takes out increasing amounts of the shorter wavelengths. Some of this depletion is scattered and results in a blue sky. If the sun's surface temperature were a little higher, the sky might appear violet (assuming our eyes would evolve accordingly). White tail deer can see easily in violet, apparently. So, if you are sneaking into a deer blind tomorrow on opening day, you might want to go a little earlier as the sky is likely bright to them.

suntrack2
2005-Nov-06, 04:12 PM
George you are correct.

George
2005-Nov-06, 08:50 PM
Thanks. It's where helichromoligsts come in handy. [Though none actually exist. :). Self-proclomations don't count, and rightfully so. ]

Ithildin
2005-Nov-07, 03:16 AM
The sun's color, as it appears, depends alot on how we percieve it. Everything from atmosphere and they way an individual's brain and eyes are 'wired' will effect this alot (for example, the sun appears red-ish on the horizon, and some people are colorblind).
This being said, the sun is actually (I'm almost certain) a yellow color. As you guys probably know, stars come in all sorts of varieties from red giants to tiny blue stars. The sun sits in the yellow part of that 'star spectrum.'
Because the light is extreamly intense, it often appears to be white.




Warning: Physicists are not allowed to read further!



And possibly another reason for this is the fear of spectroscopy being mentioned ^_^ but just in case it's not... another ways to tell the 'colors' of a star, or any object that is hot enough to emit light, is to put that light through a prism, which breaks it down in to 'spectrum lines' (which can be difficult to find with your own prism, but look extreamly cool :D ) which can be used to identify the elements that the glowing object is comprised of. However, I've never done this with the sun, only with special mercury or argon lamps, so I don't recommend trying it (because it is easy to be blinded by sunlight, so be sure to leave that to the professionals). In a way, the specturm lines are the 'true colors' of the sun.
I'm pritty sure all this is correct, but it could be wrong...
I hope this helps your quest? :)

George
2005-Nov-07, 03:24 PM
You might enjoy some of the other related threads. This one incorporates the use of a prism..... Sun's Intrinsic Color (http://www.bautforum.com/showthread.php?t=17237)

Using a simple strobe, I obtained a white appearance for the sun. However, I only reduced the sun's light by 99.9% which, surprisingly, may not be quite enough, but I'm going with it for now. :) More here (http://www.bautforum.com/showthread.php?t=7445)

suntrack2
2005-Nov-07, 03:49 PM
sun is just colorless even white color should not be there, in other words sun's color can not be define in a specific color, George, anyway you are saying white its ok, but when the massive flairs ejects through the sun is there a possibility to change of this white one? and during the sunspots on a large mass of sun what the lower layer's color indicate with which one ??
congrats for the 3000+postings GEORGE

sunil

George
2005-Nov-07, 06:37 PM
the sun rays has no specific colour, it means is it possible that sun has no colour as we are looking from earth. in one book it was written before 400 years that sun rays are colourless, when they reach through the different spheres then the rays we found colourful.
This was written prior to Newton, apparently. Prior to him, it kinda makes sense to think sunlight might have no color. Otherwise, how could sunlight cause all the objects to have so many colors if it had a color of its own, I suppose. Newton solved the mystery by running sunlight through a prism, which refracted each color, then he recombined all these colors through a second prism to produce the original white light. He reasoned that sunlight contains all these colors. I do not know of alternate ideas of sunlight after his work.

suntrack2
2005-Nov-08, 04:11 PM
George, really true one,
the topic is very nice, but the answer is very difficult for me, you know few time anyone starts assuming when he don't know the correct answer, in the verious astronimical things there is a great "probability" in assuming the things if it is unknown sometime, i cannot say confirmly that what color is of sunlight, you are quite correct in the simplification of the matter of the real possibility, and if this is your own research then that's great one, George.

whenever we look it through the prism at that time only we witness the 7 colors otherwise not, means whenever the original sunlight comes into the contact of "medium" it shows it's show of colors otherwise not it appears like white, you are really true one.

sunil

George
2005-Nov-09, 01:51 AM
It is interesting how light, and vision, was explained in the days of the early Greeks. Heron (Hero), in Alexandria, a couple thousand years ago, was regarded as the physicist of his time. He believed our eyes emitted rays to allow us to see. He assumed the speed to be infinite for these rays in order for us to see celestial bodies, such as stars.

Today, much tougher tests are done to verify an idea. The separation of colors due to a medium (refraction) is explained by the way different wavelengths travel at different speeds through different mediums. This explains further the "why" Newton had it right.

suntrack2
2005-Nov-10, 06:00 PM
George, u mean that in corona part of the eye reflecting the color of the image in a different color, or is there a possibility of prism like formation in the eye to see the white color in different colors in different situations. may be such infrastructure is within our eyes. your logic is really good going as far as color anatomy of sun rays are concern.


sunil

George
2005-Nov-10, 08:24 PM
The eye is an extremely sophisticated instrument - possibly the most ever. As sunlight passes through several layers of the eye, especially the lens, refraction which separates colors occurs. Blue light becomes separated enough from red light that it would be a problem for the eye/brain to handle. Interestingly, there are no blue color cones in the fovea (the central and mose sensitive region on the retina). [There are three types of color cones - red, green and blue; this is oversimplification, however.]The movement of the retina allows the blues to be received and processed properly, in some amazing way, no doubt.

The end result allows the eye to see color properly. White light will still look white, even though it refracts a tiny amount as it enters the eye.

I am definetly and amateur here. Yet, I think I am pretty close.

suntrack2
2005-Nov-13, 11:32 AM
that's fine george.

may be the universe is in the 3D type of visionary, our eyes filter the 3D into the correct images of the universe ? or the all images we are looking originally in inverse position our eyes are correcting that images to know to the brain that the images are in the simple position and not in inverse position, and this sort of rule may also be reflect about the white color of sun rays as far as our eyes it looks colorful at different times.

sunil

Elyk
2006-Mar-13, 03:38 PM
The sun always seems white hot in the mid day ranges. Then when it shines through more atmosphere (dusk and dawn) it turns yellow, then orange. It just depends on how much atmosphere there is in it's way. I bet if you went into space it would be even brighter and whiter since theres no atmosphere to filter it.

George
2006-Mar-13, 06:29 PM
The sun always seems white hot in the mid day ranges. Then when it shines through more atmosphere (dusk and dawn) it turns yellow, then orange. It just depends on how much atmosphere there is in it's way. I bet if you went into space it would be even brighter and whiter since theres no atmosphere to filter it.
Your view would be appreciated in this poll (http://www.bautforum.com/showthread.php?t=20208&highlight=midday).
Yes. Rayleigh scattering causes the shorter wavelengths to not reach the observer [of direct sunlight], allowing the longer and redder wavelengths to be observed.

The intensity of the sun is at least 2x that of terrestrial brightness in the blue portion of the spectrum. The overall flux is only reduced about 20%, I think, for a high altitude sun. Of course, it drops considerably at low altitudes and some what say it is zero at night. ;)]

[I thought this thread was history. :)]

suntrack2
2006-Apr-30, 10:00 AM
we are unable to state the real colour of sun, it is just impossible to assume, for the hot things we can not assume what is burning behind the flames, the only emited colour appears to be an orange, or light red or yellow only, but the original matter's colour we can state precisely.
hence the question is unanswered for me, George.

sunil

George
2006-Apr-30, 08:56 PM
we are unable to state the real colour of sun, it is just impossible to assume, for the hot things we can not assume what is burning behind the flames, the only emited colour appears to be an orange, or light red or yellow only, but the original matter's colour we can state precisely.
hence the question is unanswered for me, George.
The question is not that scientific because what light is under the surface is not an issue. The question does need some qualifying, however - "If viewed from space and with proper calibrated attenuation, what is the observed color of the sun?". The Sun is too affected by our atmosphere to gurantee a sure color result unless appropriate corrections for the atmosphere's effect are implemented.

There are several ways a sure fire result can be accomplished....
1) Have at least one astronaut look at the sun with a solar attenuation device (SAD :)) , e.g. strobe or filter, and compare the observed color to a color chart.
2) Reproduce the spectral irradiance of the sun and homogenize it into one observable spot (e.g. SPACC).
3) Develop a computer model that takes spectral irridance data and produces the correct color. [I have yet to find one that is very accurate. ]
4) Create a pure vacuum in the atmosphere that is aligned with the sun and use the SAD from option #1. :)
5) Wait a few billion years when it will always appear red, and then declare a definitive color then (red, of course ;) ).
6) [Reserved for more imaginative Baut members.]

[Added: I did leave out a balloon ride. :)]

neilzero
2006-May-01, 03:45 AM
This is an interesting thread. It seems to me we can use a prism in low Earth orbit to measure the watts per picometer of wave length of sunlight. If watts are slightly higher in the blue region, we could say the sun has a slight blue tint.
However human eyes are not linear, so perception may be a different tint. Personally, I have noticed a slight tint of yellow when the sun is high in the sky and the path through the air is relatively free of polutants and water droplets.
When my local is shadded by a cloud, the yellow tint disappears, and I would say white for high in the sky.
Typically red and orange tints are quite noticable when the sun is close to the horizon and some water droplets are in the path. Neil

George
2006-May-01, 03:03 PM
This is an interesting thread. It seems to me we can use a prism in low Earth orbit to measure the watts per picometer of wave length of sunlight. If watts are slightly higher in the blue region, we could say the sun has a slight blue tint.
This is called spectral irradiance. It is well established as seen in space. There are numerous sites which show the sun's spectral irradiance as seen through various amounts of atmosphere. The sun radiates strongest in the blue portion of the spectrum, but it is still strong in the other colors which suggests it could appear white. I suspect it is a white or bluish-white star, not yellow.


However human eyes are not linear, so perception may be a different tint. Personally, I have noticed a slight tint of yellow when the sun is high in the sky and the path through the air is relatively free of polutants and water droplets.
You are not alone. Here (http://www.bautforum.com/showthread.php?t=20208&highlight=midday) is a poll taken on this subject. Please add to it.


When my local is shadded by a cloud, the yellow tint disappears, and I would say white for high in the sky.
Please tell me what you mean. It sounds interesting.


Typically red and orange tints are quite noticable when the sun is close to the horizon and some water droplets are in the path. Neil
There is much information on this around here. Rayleigh scattering is the effect which describes how this works.

suntrack2
2006-May-01, 05:06 PM
do you think that the great proportion if we observe in the prism, when the sun rays drops on the prism, and if the yellow colour looks more intense so whether prism examination can show the rays original colour? in the old book "Dnyaneshwari" wrote by saint Dnayaneshwar who stated that sun's rays has no colour and they are colourless, but when they come out and reach through the different stages and spheres they appear as colourful.

the clouds in the sky during rainy season works like a prism and shows the colours of the rays differently i.e. in seven colours, so seven colours are the original colours of the sun rays? not probably, but see if a white colour sent through the prism say for the sake the bulb's light sent through the prism the colour will appear beyond the prism in seven colours again. if we burn the iron some blue, grinish, brown, red and yellow colours emits in the hot flames. so in my opinion the colours are much pretty decided with the properties of the original substance, and how that substance shows the colours in a specific situation that is important, hence for the sake the sun rays has no colour then the medium make it colourful and then we draw an assumption that sun's colour is red, yellow, orange likewise.

sunil

George
2006-May-01, 05:28 PM
do you think that the great proportion if we observe in the prism, when the sun rays drops on the prism, and if the yellow colour looks more intense so whether prism examination can show the rays original colour? in the old book "Dnyaneshwari" wrote by saint Dnayaneshwar who stated that sun's rays has no colour and they are colourless, but when they come out and reach through the different stages and spheres they appear as colourful. Many speculations existed about the nature of light prior to Newton. Newton was able to determine that white light, sunlight, consists of all the colors from a prism. He used a second prism that received individual colors from the first. The second prsim did not change the color of the incident light. I also read, somewhere, that he recombined the colors back into white light.

There are several factors that determine what color we see for any object. The spectral radiance of the light source, the changes to the spectral irradiance through any medium (e.g. atmosphere), the spectral irradiance changes due to the objects properties, and the properties of the eye/brain's reception. This is why color models are difficult, no doubt.

Yellow is interesting because it has a very small wavelength range in the spectrum (580nm to 590nm, roughly). Green and red are about 6x this range of wavelength. This makes yellow a good reference, btw.


the clouds in the sky during rainy season works like a prism and shows the colours of the rays differently i.e. in seven colours, so seven colours are the original colours of the sun rays? not probably, but see if a white colour sent through the prism say for the sake the bulb's light sent through the prism the colour will appear beyond the prism in seven colours again. if we burn the iron some blue, grinish, brown, red and yellow colours emits in the hot flames. so in my opinion the colours are much pretty decided with the properties of the original substance, and how that substance shows the colours in a specific situation that is important, hence for the sake the sun rays has no colour then the medium make it colourful and then we draw an assumption that sun's colour is red, yellow, orange likewise.

sunil

George
2006-May-01, 05:32 PM
do you think that the great proportion if we observe in the prism, when the sun rays drops on the prism, and if the yellow colour looks more intense so whether prism examination can show the rays original colour? in the old book "Dnyaneshwari" wrote by saint Dnayaneshwar who stated that sun's rays has no colour and they are colourless, but when they come out and reach through the different stages and spheres they appear as colourful. Many speculations existed about the nature of light prior to Newton. Newton was able to determine that white light, sunlight, consists of all the colors from a prism. He used a second prism that received individual colors from the first. The second prsim did not change the color of the incident light. I also read, somewhere, that he recombined the colors back into white light.

There are several factors that determine what color we see for any object. The spectral radiance of the light source, the changes to the spectral irradiance through any medium (e.g. atmosphere), the spectral irradiance changes due to the objects properties, and the properties of the eye/brain's reception. This is why color models are difficult, no doubt.

Yellow is interesting because it has a very small wavelength range in the spectrum (580nm to 590nm, roughly). Green and red are about 6x this range of wavelength. This makes yellow a good reference, btw.


the clouds in the sky during rainy season works like a prism and shows the colours of the rays differently i.e. in seven colours, so seven colours are the original colours of the sun rays? not probably, but see if a white colour sent through the prism say for the sake the bulb's light sent through the prism the colour will appear beyond the prism in seven colours again. if we burn the iron some blue, grinish, brown, red and yellow colours emits in the hot flames. so in my opinion the colours are much pretty decided with the properties of the original substance, and how that substance shows the colours in a specific situation that is important, hence for the sake the sun rays has no colour then the medium make it colourful and then we draw an assumption that sun's colour is red, yellow, orange likewise.
The medium only alters the color. This can be seen by comparing space telescope images with earth-based images. Apollo color images on the moon reveal the lack of medium is not a color factor.

suntrack2
2006-May-02, 01:07 PM
then on moon how the prism will show its colours according to earth or it will some different. "as you said above the Apollo color images on the moon reveal the lack of medium isnot a color factor." our eyes are the great prism who can create a colorful image of a sustance when the light fall on it, so is their in inbuilt speciality in our eyesight to see the thing colorful, and also for rays the eye reads its color and then we presume well that such and such color is there, and for the color blindness fellow, how he will judge the real color of sun!, may be the orange color for the color blindness fellow can read as red!.

George
2006-May-02, 01:48 PM
then on moon how the prism will show its colours according to earth or it will some different. "as you said above the Apollo color images on the moon reveal the lack of medium isnot a color factor." our eyes are the great prism who can create a colorful image of a sustance when the light fall on it, so is their in inbuilt speciality in our eyesight to see the thing colorful, and also for rays the eye reads its color and then we presume well that such and such color is there, and for the color blindness fellow, how he will judge the real color of sun!, may be the orange color for the color blindness fellow can read as red!.
The eye is amazing in complexity. It consists of three different color cones - red, green, and blue receptors. [This is a simplification because each of these color cones can see other colors weakly.] There are also receptors known as rods.

In dim light, the rods dominate your "seeing". As the sun sets you might try and notice when you colors fade away from objects.

You are correct that the eye is a prism, somewhat. The lens of the eye will refract color slightly and move blue light to the side. Interestingly, there are no blue cones in the central and highly sensitive (very densely packed cones) region of your retina known as the fovea. Your eye moves around, so I understand, which allows the blues to be received and added to your brain's color equations.

The complication in determining just how the brain would interpret a given spectral irradiance should be very difficult. The better way to resolve the sun's color is to actually reproduce the spectral irradiance and let the eye look at it. This was the purpose for developing the SPACC prism system made last year. It uses sunlight which has been weakened in blues and other wavelengths but the SPACC corrects these atmospheric losses and restores the sunlight beam to its pre-atmosphere spectral irradiance. It then is focused into a spot that reveals the true color of the sun. However, the spot is more of a thin small rectangle, with some blue slightly outside of the main bright portion. Therefore, SPACC needs some tweaking to give a sure-fire result. Nevertheless, it seems obvious that the sun should be white or bluish-white because the spot is white with some blue still needing to be added to it. Adding blue to white will not produce yellow. Therefore, the sun is not yellow, which other evidence also supports.

suntrack2
2006-May-03, 10:54 AM
that's fine, say for the sake, the tiger or other wild creature can look in the dark night, in their eyes there is a facility to see the night images, their eyes functions just like "night vision goggle", if they can see in the dark night so there must be a possiblity of getting the image in "eighter shadow", or in a deem ash color light they may be see through their eyes and they able to navigate their targate, it means that " their eyes are very well define the black color in the night turn into visible", so can such eyes experience the sun's color more different, or they will experience the sun's color is black, when they are able to see black into white, then white color may be appear in their eyes as black?

I found some sites to read and hence giving here to read, ( I don't know whether the permission has to take to attach their url here) but I am attaching here. :-

http://www.madsci.org/posts/archives/1999-12/945169710.As.r.html
http://www.vasc.org/erc/colors.html
http://casa.colorado.edu/~ajsh/colour/Tspectrum.html

George
2006-May-03, 01:29 PM
that's fine, say for the sake, the tiger or other wild creature can look in the dark night, in their eyes there is a facility to see the night images, their eyes functions just like "night vision goggle", if they can see in the dark night so there must be a possiblity of getting the image in "eighter shadow", or in a deem ash color light they may be see through their eyes and they able to navigate their targate, it means that " their eyes are very well define the black color in the night turn into visible", so can such eyes experience the sun's color more different, or they will experience the sun's color is black, when they are able to see black into white, then white color may be appear in their eyes as black?
Animals have quite a range of eyesight. I know very little, however, of any specifics. White tail deer have several enhancements that allow them to see some things much better than us. They can see slightly into the UV range. So, when you and I can not quite see skylight when the sun is over the horizon, they probably can. They are likley watching all the deer hunters sneak into their deer blinds. :)

Reptiles, I think, are capable of the lower end, which you mentioned. They sense IR which allows night hunting. Sometimes "eyes" aren't what we might call their seeing abilities in this case. Bats and dolphins are other examples of seeing in different ways.


I found some sites to read and hence giving here to read, ( I don't know whether the permission has to take to attach their url here) but I am attaching here. :-
I see no reason why any link would be not allowed.

suntrack2
2006-May-04, 11:36 AM
thanks george for the reply. well when we know that water is of white color but when we go under the sea and try to watch the outside from the water the water appears clear blue, in fact there is a mass shadow of the blue sky in the sea water and when we observe the color "blue" from the water particularly in the day time, if we are saying that sun's color is white but when it comes on earth with the glaze of some yellowish or a orange shade then we look it as yellow or orange, means the original color may be white of the sun, I am suspicious. and when we look beyond any flame if the flames are not thick but if they are think then we can see the same color in the back of the flame, even we can see beyond the flame but in the same flame's color. The burning material on the sun is appearing in the yellow color mostly and when the light scatter in the sky the rays appears as yellow early in the morning, but at noon i.e. on 12 morning the rays color appears with a very light white with a yellow glaze in it. so white and yellow has some co-relation with the sun's original color, do you not think so.

sunil

George
2006-May-04, 12:42 PM
thanks george for the reply. well when we know that water is of white color but when we go under the sea and try to watch the outside from the water the water appears clear blue, in fact there is a mass shadow of the blue sky in the sea water and when we observe the color "blue" from the water particularly in the day time...
Water is blue primarily because it absorbs more of the other colors. The blue sky reflection certainly helps, but water will be blue indoors, too.


...if we are saying that sun's color is white but when it comes on earth with the glaze of some yellowish or a orange shade then we look it as yellow or orange, means the original color may be white of the sun, I am suspicious. and when we look beyond any flame if the flames are not thick but if they are think then we can see the same color in the back of the flame, even we can see beyond the flame but in the same flame's color. The burning material on the sun is appearing in the yellow color mostly and when the light scatter in the sky the rays appears as yellow early in the morning, but at noon i.e. on 12 morning the rays color appears with a very light white with a yellow glaze in it. so white and yellow has some co-relation with the sun's original color, do you not think so.
I see the mid-day sun as white, but a small majority of others seem to see it as yellow-white at around noon. I used a paper plate painted black and glued a pencil into it so that I could spin it with an electric drill. I then cut about a .5 mm slot in it not far from the edge. This gave me a strobe that allowed me to reduce the sunlight into my eye by 99.9%. [I call it the SAD (Solar Attenuation Device) partly because it cost about 15 cents to make. :) ] It appeared white at mid-day once again, yellow near the horizion.

The atmosphere is real reason why the variation in spectral irradiance occurs. In other words, the intensity of each wavelength of light is altered. Blue wavelengths (around 450 nm) are reduced the most, partly because they scatter the easiest. Then there are molecules that snag certain wavelengths with glee and "absorb" them.

However, sometimes the color is altered when a separate source of color is around to force your brain to compare colors. Your flame example would alter slightly what color you would see simply because it would force any other color seen behind the flame to be in contrast to the yellow flame. Once again, the advantage of the SPACC is it eliminates all the conflicting effects by faithfully reproducing the original spectral irradiance of the light source into one observable spot for the eye to "see" the true color. [It is not quite perfected, yet.]

suntrack2
2006-May-04, 05:21 PM
yes, you are quite true and that expriment is so nice to apply, that sad (solar atenuation device), if we look towards sun (with closed eyes) early in the morning we can look red color in our closed eyes, if we look at the sun in the noon white+black color appears in our closed eyes. I did this experiment.

George
2006-May-04, 06:19 PM
if we look towards sun (with closed eyes) early in the morning we can look red color in our closed eyes, if we look at the sun in the noon white+black color appears in our closed eyes. I did this experiment. That is an easy and interesting experiment. Don't you think red color has anything to do with your eyelid altering the color? The difference in intensity also is a factor.

suntrack2
2006-May-07, 08:01 AM
the color information to the brain reach through the eye nerves, and brain car work then like a main server of lan machine, brain can read the eye's readings of images and other readable material. to recall the things we many time close our eyes to remember the things properly.

There is a vast link of the inner nerves of the eyes. do you think george, that the sun light reach to earth in pigmentation, or it is just reaching in its own form in invible color mode. infact for sun there is no specific color but in the continuous fusion process the burned material reflcts or prepare the yellow lihgt.

George
2006-May-08, 01:07 PM
the color information to the brain reach through the eye nerves, and brain car work then like a main server of lan machine, brain can read the eye's readings of images and other readable material. to recall the things we many time close our eyes to remember the things properly.

There is a vast link of the inner nerves of the eyes. do you think george, that the sun light reach to earth in pigmentation, or it is just reaching in its own form in invible color mode. infact for sun there is no specific color but in the continuous fusion process the burned material reflcts or prepare the yellow lihgt.
Each photon of light has a certain amount of energy (E=hf). Our eyes are only sensitive to the photons which have energy where the frequency of light, f, falls within the visible spectrum. These photons have no color attribute of their own; it is the process which happens within each color cone that sends the appropriate signal to our brain which renders the color.

suntrack2
2006-May-09, 04:03 PM
in the above context, I would like to further say that sun's original color may be like " the electricity waves in the thundering clouds", and when such whitish light enter in our atmosphere it appears like yellow, or reddish in the morning and in the evining, these are the impacts of "carbonic layers" on the horizones both at east side and at the west side, as appear when we are in the directions to the sun at the time of sun rise and sun set. the original color of light of the sun is mostly white. !

sunil

gtbloke
2007-Feb-24, 12:59 PM
to human eyes under the blanket of the atmosphere... the sun appears to be yellowish white, from space it would be white to pinkish going from this study http://casa.colorado.edu/~ajsh/colour/Tspectrum.html

but to the everyday human eye the sun really does appear white !

George
2007-Feb-26, 03:13 PM
to human eyes under the blanket of the atmosphere... the sun appears to be yellowish white, That is the view of a slight majority around here. Please cast your vote, too, in the Midday Sun Poll (http://www.bautforum.com/showthread.php?t=20208).

Just why yellow is seen is unclear because if you project the solar image onto a white card, only white is seen, at least for me. Also, just for kicks, I used a simple strobe (SAD - Solar Attenuation Device :D ) and the sun appeared only white. Also, the clouds do not look yellow-white and they reflect light evenly, as I understand. Regardless, yellow is often seen.


...from space it would be white to pinkish going from this study http://casa.colorado.edu/~ajsh/colour/Tspectrum.html Yes, that one has been around for a while. It is a computer estimated color. I think it is incorrect.


but to the everyday human eye the sun really does appear white !


The simplest and biggest argument favoring white, especially over any yellow addition, is the fact that unfiltered solar projections at solar observatories produce only a white image of the disk (http://www.bautforum.com/showpost.php?p=762745&postcount=15). Since the atmosphere diminishes (extinctions) more of the blue end of the spectrum than the red, then adding more of the blue end back into the color would produce more of a blue or blue-green color, but only if enough is added. However, I think there just isn't enough to make the sun's color change from white.

[Quicly added: There is a likelyhood that the central region of the sun would indeed look bluish-white (assuming one adequately reduces the intensity to the eye).]