What Colour Is The Sun?
What Colour Is The Sun?
The question "What color is the sun?" may seem straightforward, with a commonly accepted answer that it is yellow. However, the truth is more complex, as the perception of color is influenced by various factors such as the wavelength and intensity of light, environmental conditions, and the limitations of our eyes and brain. The sun emits a "black body spectrum" that covers a range of wavelengths, from infrared to ultraviolet, and even x-ray and gamma ray radiation during solar flares. While the sun emits most of its energy at around 500 nm, which is close to blue-green light, it also emits strongly in all visible colors, resulting in a perceived white color when viewed from space. On Earth, the atmosphere plays a role in the color of the sun, with shorter wavelength blue light being scattered more efficiently than longer wavelength red light, and all visible wavelengths of light being attenuated. This results in a perception of the sun as having a little less blue and more yellow. Sunrises and sunsets, with their longer path through the atmosphere, scatter even more blue light, making the sun appear redder. Therefore, there is no single answer to the question of the sun's color, as it depends on various factors, but any answer can be defended.
Why does the sun sometimes appear different colours?
So, what causes the striking color change of the rising sun? The answer lies in Rayleigh scattering. The atmosphere contains tiny particles that scatter incoming sunlight in various directions, with the main scattering process being highly dependent on the wavelength of the light. A simple dimensional analysis shows that blue light, which has a wavelength of around 400nm, scatters about nine times more effectively than red light in the 600-700nm range.
This scattering process is largely responsible for why the sky appears blue, as blue light is scattered down toward the ground. When the sun rises in the east, the blue light that contributes to blue skies gets scattered, making the rising sun look red. This effect is most noticeable near the horizon because when the sun is near the horizon, its light passes through more atmosphere than when it's directly overhead. This provides more opportunities for the light to scatter out and produce the striking color change of the rising sun.
The science of light rays
When we see objects, their perceived colors are determined by the wavelengths of light that are either reflected or transmitted, as well as those that are absorbed by the object. This is because different colors correspond to different wavelengths of light.
For instance, a red shirt appears red because the dye molecules in the fabric absorb light from the violet/blue end of the spectrum, and only reflect red light. If a red shirt is exposed to only blue light, it will appear black since blue light will be absorbed, and there will be no red light to reflect.
White objects, on the other hand, appear white because they reflect all colors, while black objects absorb all colors, resulting in no reflection of light.
