Why do people think that the sun is yellow?

Question

As you can see in this image, (http://en.wikipedia.org/wiki/File:The_Sun_by_the_Atmospheric_Imaging_Assembly_of_NASA%27s_Solar_Dynamics_Observatory_-_20100819.jpg) it is clearly orange.

Answer 1

If you read the text that accompanies the image, you will see that this is a false color image. That means that it was taken using methods that do not provide the same colors that we would see with our eyes. But that's sort of beside the point anyway. The light from the Sun, when it is analyzed across its full spectrum, has its highest amplitude in the yellow-green portion of the visible spectrum - right in the middle of our eyesight capability. That's not too surprising when you think about how evolution works. But what that means is that the Sun is more yellowish green than anything else, in terms of spectral amplitude. The astronomical term for a star like ours along the Main Sequence is a yellow dwarf. That does not mean that it is a pure yellow in color. In fact, when we see the Sun, what we perceive is white light - not orange, not red, not yellow - white.

Answer 2

Yellow

Answer 3

I guess you have not heard about "false colour photography".



For example, when I take pictures in infrared light, I have to show the picture in false color (in this case, I have to use visible colors instead of infrared) because real infrared is invisible to the human eye.



The caption to the picture in your link, states:

"This is a false-color image of the Sun observed in the extreme ultraviolet region of the spectrum"



Ultraviolet is a color that our eyes CANNOT see. It is possible to rig a camera so that it will catch the image of the Sun in ultraviolet. But if you showed it in ultraviolet (true color), then it would be invisible (because... we can't see ultraviolet).



Therefore, they have to change the colors (hence the caption "false-color") and they decided to use various shades of red to represent the various shades of ultraviolet.



If they had picked shades of green, would you assume the sun is green?



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As for you original question

--"Why do people think that the sun is yellow"



The answer is rather simple. The sun is roughly white. In astronomy, we use "color-temperature" for a precise decription, and white is normally defined as the color of a "blackbody" heated to 6000 K. The Sun's effective temperature is around 5700 K -- very close to white, but ever so slightly on the yellow side of pure white.



The difference is not enough to be detected by eye. However, it is enough for most astronomy books to describe the Sun as a "yellowish" star.



In addition, most people see the Sun in Earth's sky, where the air filters out some of the blue light by diffraction (that is why the sky appears blue -- it steals the blue light from the Sun).



White - blue = yellow.



This filtering out of blue, leaves the Sun looking a bit yellowish, even to the eye. Therefore, to most people, the Sun does look a bit yellowish (when compared to "pure white").



When the Sun is close to the horizon (sunrise or sunset), its light has to cross a longer path through the atmosphere before reaching our eyes (or our cameras) so that a lot more blue light is removed by the air, and even a bit of green. This leaves the Sun looking orange or even red.



Using primary color algebra:



red + green + blue = white



Therefore



white - blue - green = red.

Answer 4

The Sun is white.



It may look yellow or orange depending on the angle at which its light passes through our atmosphere. Pollution and other particulates in the atmosphere can also affect it.



The image you linked to is a false-color image; it's actually showing you ultraviolet wavelengths. This is stated explicitly in the text below the image, in three different languages.

Answer 5

it is clearly orange.



Go to the source: http://sdo.gsfc.nasa.gov/data/



The point is made starting at minute 15:20 in this video: http://www.youtube.com/watch?v=3r0n_8xi4Mc#t=15m20s



At some point, you'll realize that you're looking at images which are colored to represent additional information, and that the choice of color is not too relevant to the physical phenomena being illustrated.

http://en.wikipedia.org/wiki/File:WMAP_2010.png



But at least it was a bit more subtle trolling, though. The obvious gets old very fast.

Answer 6

The sun is white.



When people take photos of it they do so when the sun is low in the sky. It looks orange because of the thickness of air the light has travelled through.



The colour of the sun at midday however is nearly perfect white (not a coincidence, we have evolved to see mixture of colours produced by the sun as colourless)



If you were to get above the atmosphere you would see a slightly yellow tinge to the sun

Answer 7

Because the Earth's atmosphere and the molecules in the atmosphere filter white sunlight so that yellow wavelengths of light reach Earth's surface. The Sun is white, BY DEFINITION, NOT orange, pink or red because refraction of sunlight by the atmosphere or because of photographic filters.



"...What Color is the Sun?







Though humans perceive the sun as yellow when they look directly at it, it is actually white. The sun is made up of a collection of gases, such as helium, hydrogen and other elements, and is so hot that it emits a white light. If you were to look at the sun in outer space rather than through Earth's atmosphere, the sun would appear to be whitish in color rather than golden. This is because the appearance of the sun's rays is distorted as they pass through the Earth's atmosphere.





Why Does the Sun Appear Yellow to Humans?







The sun appears yellow to humans because that is the way the light from the sun is interpreted after it strikes our visual cortex. Though the sun gives off white light, the sun's rays are filtered when they enter the atmosphere. The elements in the atmosphere filter out the blue components of the white spectrum in the rays. The blue components are filtered out, leaving predominantly reddish-yellow components behind. The rays are then processed as yellow by our visual cortex..."



http://www.ehow.com/how-does_4910119_we-perceive-sun-as-yellow.html





http://www.ehow.com/how-does_4910119_we-perceive-sun-as-yellow.html

Answer 8

If we were in outer space the Sun would look white. The atmosphere scatters the bluer wavelengths making the Sun look yellowish when it is above the horizon. At the horizon the Sun's light must pass through more layers of the atmosphere, the extra atmosphere scatters the shorter visible wavelengths making the Sun look red.

Answer 9

The sun is actually brightest in the yellow-green part of the spectrum, but that is only a slight bias. The sun appears white to our eyes because the sheer brightness of it overloads our color receptors. In photos in can appear orange or red due to atmospheric effects or false coloring of wavelengths beyond the visible.

Answer 10

Actually the Sun is neither yellow nor orange; it is white. That picture is taken through a special filter which emphasizes the hydrogen gas in the Sun, which is red/orange. When seen through an ordinary telescope, the Sun is actually pure white.

Answer 11

In space the Sun looks white. From the ground it looks yellow because some of the blue light is scattered and creates the blue appearance of the rest of the sky.

Answer 12

Our own sun star a hot inferno plasma of nuclear fusion is always white it was white all long as here on earth see white naturally appearance and evenings see it yellow , orange and reddish as its color spectrum of color wave lengths plus earth atmosphere gases plays tricks on us as it looks yellowish, orange or reddish. NASA uses false-coloring so they can understand sun star surface and weather patterns like solar wind or even powerful CME storms as they yellow because yellow best color to understand. Face the facts our own sun star is white and not yellow its white plasma inferno sphere and all G type stars are white.

Answer 13

The sky is blue - so a white bright object appears yellow compared to the blue sky.

All photographs are innacurate - the colours are a product of the sensing and replication process.

Take a photo - print it out big - go back to where you took the photo - it is different.

Answer 14

In terms of radiation from its surface, it peaks in the yellow end of the spectrum. It appears orange in the image you have linked due to filtering to allow for its surface features to actually be visible. If you were looking at it with the naked eye and no filtering and you were close enough for it to appear that large, it would appear WHITE as even the bands in which it most weakly radiates visible light would still be too saturated for your eyes to handle.

Answer 15

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Answer 16

It is colored as yellow in cartoons. If you look at the sun for some dumb reason, it looks white or yellowish

Answer 17

It's blue.



http://csep10.phys.utk.edu/astr162/lect/sun/bluesun_soho-small.jpg