The human eye can detect the radiation of the sun in the visible spectrum. The sun's radiation spans the entire electromagnetic spectrum, of which visible light is a small part.
The electromagnetic radiation emitted by the Sun is fairly uniform across the visible spectrum so, yes, the Sun is white. It is fairly close to white even at the surface of the Earth, but the spectrum is affected primarily by Raleigh Scattering which makes the sky look blue. The scattering is proportional to the fourth power of the frequency and to the depth of the atmosphere, so the sky looks bluer nearer the horizon and, as you will be aware, the Sun looks redder at Sunrise and Sunset.
The shorter wavelengths are more likely to be scattered by the atmosphere and the longer wavelengths tend to make it through and that's why the sun appears yellowish, reddish and orangish when the sun is close to the horizon as it has to travel through a lot of atmospheric intervention.
So why does the sun appear blindingly white when it is overhead or when viewed from space?
When the sun is overhead, light has to deal with less atmospheric intervention and is more bluish (search a dictionary for bluish and you will get this: Of the color intermediate between green and violet; having a color similar to that of a clear unclouded sky). The blue photons get scattered away easily making the sky appear blue.
But the sun appears blindingly bright and white when it is overhead. That's due to the way color receptors in our eyes behave when they're subjected to excessive light when the sun is overhead and light has to deal with less atmospheric intervention. Our eyesight is trichromatic, meaning we have three types of color receptors -- red, green and blue. When these color receptors are subjected to excessive light when the sun is overhead, the brain will produce a white sensation for the bright object being observed, which makes it impossible to perceive the color of that bright object. The Color Of The Sun, Part II
Also when viewed from space, without the atmosphere to scatter away the component spectrum of visible light, the sun appears white. Add the above reason to this (when the sun is viewed without a visor) and the sun appears white and blindingly white
In astrophysics, stars are classified by their surface temperature, that is associated to specificspectral patterns. An early schema from the 19th century ranked stars from A to P, which is the origin of the currently used spectral classes. After several transformations, today the spectral classification includes 7 main types: O, B, A, F, G, K, M. A popular mnemonic for remembering this order is "Oh, Be A Fine Girl,Kiss Me".
This is called "Morgan-Keenan spectral classification", even though its form was already by Annie Cannon, also based on the work of other astronomers from the Harvard College Observatory. The classes, listed from hottest to coldest, are:
Class Temperature Star Color
O 30,000 - 60,000 K Blue
B 10,000 - 30,000 K Blue
A 7,500 - 10,000 K White
F 6,000 - 7,500 K White (yellowish)
G 5,000 - 6,000 K Yellow (like the Sun)
K 3,500 - 5,000 K Orange
M 2,000 - 3,500 K Red
Notice that hottest stars are blue, while coldest stars are red. This seems unusual to most people, who associate red with hot and blue with cold. This is because we see fire as yellow, orange or red, but light produced by hotter sources is blue. However, blue sources are hard to find on Earth because it requires a large amount of energy.
If you could travel into space and look at the Sun, you’d find that it’s actually white, and not yellow. At sunrise and sunset times it appears yellow, orange, or
red sometimes; this is due to the pollution in the atmosphere through which we
are looking at the horizon.
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