I have always wondered, since the hottest color of fire is blue, why is the sun yellow and not blue?
We only see the surface of the Sun, called the photosphere. It is much cooler than the center – about 5400 Celsius (compared with millions of degrees Celsius at the center).
The blackbody radiation profile for a 5400 C object corresponds to yellow-white, as perceived by the human eye.
March 30th, 2010 at 8:13 pm
We only see the surface of the Sun, called the photosphere. It is much cooler than the center – about 5400 Celsius (compared with millions of degrees Celsius at the center).
The blackbody radiation profile for a 5400 C object corresponds to yellow-white, as perceived by the human eye.
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March 30th, 2010 at 8:30 pm
The surface of the sun isn’t that hot.
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March 30th, 2010 at 9:04 pm
Composition
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March 30th, 2010 at 9:32 pm
The sun is actually white (it only looks yellow because some of the blue wavelengths of sunlight have been scattered by the atmosphere).
Blue stars (stellar class O) are the hottest with surface temperatures over at 30,000 Kelvin.
Our sun isn’t that hot – its only about 5,780 Kelvin and so appears white.
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March 30th, 2010 at 9:50 pm
The sun is a ball of gas. If the sun was fire, it won’t be able to survive for the extreme lack of oxygen that fire needs to survive.
Thus, the sun isn’t blue
(that would be cool though;)
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March 30th, 2010 at 10:17 pm
Simple, its surface is just not hot enough.
To be blue, the sun may need more than twice its current surface temperature to do so. However, dig deeper into the sun and you will "see" it to be blue, alot bluer. Tis core temperature is 15 million Kelvin.
Clear skies!
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March 30th, 2010 at 10:33 pm
Because the sun isn’t the hottest of stars. Sirius and Rigel are blue stars (both are easily seen in Orion — Sirius is Orion’s dog. It’s an average star in a backwater suburb of an average galaxy (and you thought you were special).
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March 30th, 2010 at 10:48 pm
The sun emits light in all the wavelengths of visible light as well as electromagnetic radiation in the range much lower and much higher than that of visible light.
If the suns light were put through a prism it would form a rainbow. If we then measured the energy of each colour we would find that the green colour would have the highest amount of energy. This is the colour that is smack bang in the middle of the rainbow of visible light.
What a coincidence? Maybe not. The human eye is sensitive to the light that is the most abundant in our environment, not really a surprise. Is it also a surprising that this is the mixture of light radiation that we define as white.
The colour (or wavelength) with the most energy when comparing light from various sources can tell us the temperature of that source. This is how astronomers can tell the temperature of stars in the universe.
When that peak in energy shifts to the lower frequencies the temperature is lower than the suns temp, the peak is closer to red, the source looks reddish. If a stars peak is in the blue region then the temperature is hotter than the sun and it appears blue.
Although this relates well to the case of the flame, unfortunately it is not the case. The flame is at a much lower in temp than the sun and the colours that we see are generated by the chemicals in the flame.
If the light from the flame were put through the prism as above many colours would be missing, and it is this mix of colours that gives the flame the colour.
This is the same effect as the different chemicals in fireworks giving the colour to the bursts of flame.
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March 30th, 2010 at 11:30 pm
The sun is not fire. It is a thermonuclear reaction.
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March 30th, 2010 at 11:45 pm
Because it’s not that hot.
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