What is the Color of the Sun?
The sun is our major source of light and heat for our planet. It spreads a variety of distinct colors across the sky every day. It is fascinating to see the sky change its hues from light red to bright golden shimmer and then to a pink glow during the sunset. Just by looking at the sunlight, one often thinks that sunlight is yellow and then, it gradually changes to orange. However, upon closer scientific inspection, the facts point to something else entirely - that sunlight is actually white in color. But on deeper inspection, the white light of the sun is divided further into seven colors of the rainbow. So, let us understand what color sunlight exactly is and why it is so.
The Colors Present in Sunlight
Let us visualize the colors present in sunlight with the help of a simple experiment:
Take a glass prism and set it up in a dark room near the window such that direct sunlight falls on the prism through a small aperture in the window.
Fix a whiteboard to capture the rays passing out of the prism.
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The observation shows that the whiteboard has a spectrum of seven distinct colors, which are the colors of the rainbow, i.e., violet, indigo, blue, green, yellow, orange, and red.
Thus, we can conclude that the white light of the sun’s rays is actually made of a combination of seven constituent colors.
Why are there 7 Colors in Sunlight?
The sun’s rays are actually white in color and form a mixture of the seven colors we see in a rainbow, i.e., Violet, Indigo, Blue, Green, Yellow, Orange, and Red, commonly called VIBGYOR. The sun appears to have different colors during the course of a day because of a process called dispersion. Dispersion of light is a phenomenon by which white light splits up into its seven constituent colors, due to the refractive index of the surface of incidence, and the different speeds the different constituent colors have in a medium. The refractive index of a material is defined as a dimensionless number that can describe how fast light travels through a particular material. Different lights have different wavelengths, and hence, different refractive indices in a given material. This causes them to split apart from the original white light, and form a spectrum of the seven colors.
The Different Colors of the Sun at Different Times in the Day
The earth’s atmosphere is made up of various different gasses like oxygen, nitrogen, and carbon dioxide. In addition, there are other impurities like dust, smoke particles, and polluting gasses like methane and CFCs. When the sun's rays strike the earth’s atmosphere to pass through, they are distorted by the earth’s atmosphere due to the presence of all these materials in the atmosphere. As demonstrated earlier, different colors present in the spectrum have different wavelengths.
The wavelength of a material can be defined as the distance between two successive crests(highs) or two successive troughs(lows) of a wave. So, the longer the wavelength, the lower the frequency. Thus, blue and violet are scattered more because of their short wavelengths. Conversely, colors of the other end of the spectrum do not get scattered as much, because they have longer wavelengths. Thus, there are different colors of the sun at sunrise and sunset.
When the sun is directly over us during late morning and noon, the sun’s rays are subject to the least amount of interference because the distance traversed by the rays is the least at that time. Therefore, during this period, blue light gets scattered, and the sky appears to be blue, while the sun’s rays appear to be yellow.
During sunrise, the sun is at its farthest, seemingly rising from the horizon. As a result of this, the light rays have to travel a much longer distance through the atmosphere. Therefore, they are obviously subject to more interference, resulting in an increased amount of scattering. Consequently, out of all the colors, the red light is least scattered. The same phenomenon occurs during sunset when the sun is seemingly moving towards the horizon, and as a result, the sunlight color appears to be of varying shades of red and orange during the dawn and dusk.
Sunlight
Sunlight can be defined as the energy and light which comes from the Sun. It is called insolation when the sun's energy reaches the earth’ surface. What the dwellers of the earth experience are the solar radiation of the sunlight. The heat and radiation from the Sunlight come in the form of electromagnetic waves. When the solar radiation enters the earth, then the atmosphere absorbs about 16% of the solar radiation and some 6% is scattered to space. 28% of the solar radiation is reflected by the clouds and about 47% reaches the earth’s surface. Without the presence of sunlight, no life could survive on the planet. The plants require sunlight for making food by the process of photosynthesis. Here, the plants use solar energy, water and carbon dioxide to form carbohydrates and oxygen. Thus, without sunlight, no life will be able to survive on earth. Solar energy can be both beneficial and harmful for us. The human body requires sunlight for the synthesis of vitamin D in their body. But if there is an excess of sunlight then the radiation can lead to sunburn and skin cancers.
FAQs on Is Sunlight White or Coloured?
1. What is the color of sunlight?
The color of sunlight has been found to be white. The sun emits the colors of the rainbow we see and all the colors combined forms the color white. It is because of the sunlight’s color, we can see the world with sunlight’s illumination. When we see the sunlight pass through a prism, we observe the dispersion of light which gives a color combination of seven different colors. Thus, we observe a green leaf as green and all the colors differently. The fundamental colors that are present in a rainbow and how it is split by mist and there are no colors missing can be considered as the direct evidence that white is the color of the sunlight.
2. What is a rainbow?
A rainbow can be defined as the phenomenon which is created because of reflection, dispersion, and refraction of sunlight in the water droplets that result in a spectrum of light that we can observe in the sky. We can see it as an arc that is multi-colored. The rainbows that are caused by sunlight appear in the sky which is the part opposite to the Sun directly. Rainbows are at times full circles but the observer only sees half of it, seeing it as an arc.
3. Why do we see different colors at sunset and sunrise?
We see different colors during sunset and sunrise because of the following reasons:
During late morning and noon, the sun is directly above us and the sun rays have the least amount of interference as the rays’ distance traversed is lowest at this time. Thus, we see the blue light scattered and the whole sky appears blue.
During the time of sunrise, the sun is at the farthest distance. The light rays traverse a longer distance and are subject to more interference. This results in a larger scattering of light and the red light is the least one to be scattered. This is similar during sunset. Thus, we observe a red and orange shade during dusk and dawn.
4. What is VIBGYOR?
VIBGYOR is the name of the colors we observe when the sunlight gets dispersed. We can see this during the appearance of a rainbow. Here, there are the seven colors of the spectrum of white light i.e. the sunlight. V means violet, I stands for Indigo, B is for blue, G is for green, Y is for yellow, O is for orange and R stands for red. Thus, VIBGYOR is related to the phenomenon of light dispersion.
5. Why is the sky blue in color?
The sky is blue in color because of a phenomenon called the Raleigh scattering. Here, scattering means the scattering of electromagnetic radiation or light by a smaller wavelength. The sunlight is scattered by particles present in the atmosphere and the smallest wavelengths of light are easier to get scattered. Blue has the shortest wavelength and thus, the sky is blue in color due to this phenomenon. Blue gets easily dispersed by the particles and this makes the sky appear blue in color.
6. Why does a rainbow show all seven colors of the white light of the sun?
Rainbows are formed in the sky when the light radiations of the sun come in contact with water droplets in the atmosphere. Rainbows seem to show all the seven colors of the spectrum because the water droplets in the air during/after rain, break the sunlight into the seven colors of the spectrum. This works in the same way as our previously demonstrated experiment of passing sunlight through a prism. The water droplets in the atmosphere act as prisms to achieve a similar effect. When the light rays strike a water droplet, they are refracted at the boundary of air and water, and enter the droplet, causing the white light to be dispersed into the constituent seven colors. Consequently, the brilliant rainbow effect is formed by the light then reflecting inside the droplet and finally emerging out into the air after another refraction at the reflected boundary.
7. How is Light produced by the Sun?
The sun contains massive quantities of helium and hydrogen, and generates huge amounts of energy at its core, through nuclear fusion, by converting hydrogen to helium. The huge mass of the sun squeezes the hydrogen at its core, in a way where four hydrogen nuclei combine to form a single helium atom. This process is called nuclear fusion, resulting in some mass of the hydrogen atoms being converted into light and heat energy. However, if it wasn’t for the sun’s enormous gravitational force, the star would have exploded due to expansion from the heat generated, which is around 5600 oC on its surface.
