Whenever it rains, you all keep peeking through your windows, looking at the sky in the hope of seeing that colourful rainbow. One that fills you with hope and curiosity to know more about it. Whether you are an adult or a kid, you feel deeply connected with rainbows as they provide you with joy. Though a lot of people see them occasionally, very few know about the facts associated with rainbows, like how many colors are in the rainbow, or, what is the rainbow colour order? Some may even know the answer to these but don’t know the science that works behind this natural wonder.
1. How many Colors are in the Rainbow?
Rainbow arcs are a result of both the reflection and refraction of light. They are produced when sunlight strikes water droplets. The light is first refracted while entering the droplet and then it is reflected by the back of the droplet. This reflected light is then again refracted while leaving the droplet. This refraction happens at multiple angles.
This phenomenon divides the sunlight into colors of different wavelengths. This distribution gives the familiar colored rainbow arc you are used to and will tell you how many colors are in the rainbow. The colors of the rainbow displayed are Red, Orange, Yellow, Green, Blue, Indigo, and Violet. (See Why Do Rainbows Form?)
2. Are there 6 or 7 Colors in the Rainbow?
If you are still wondering about how many colors are in the rainbow? Then the answer is simple. Rainbows are a spectrum of different colours which are refracted by the water droplets. Sunlight appears white to your eyes but when it enters a water droplet, it is first refracted while entering it and then is reflected by the back of the droplet. This light is again refracted at multiple angles as it exits the droplet. The sunlight is refracted as 7 colours of different wavelengths. These 7 colors are mentioned in the above point. Thus this proves that a rainbow has 7 colours. (See What causes Double Rainbow?)
3. Why are there 7 Colors in the Rainbow?
If you are asked how many colors are in the rainbow? Then you will instantly answer seven. But have you ever wondered why only 7? Why not 6 or 8 or any other number? Well, the world didn’t always believe that there are 7 colors in the rainbow, scientists like Robert Boyle believed there are 5 colours in the rainbow and wrote the same in his book Experiments and Considerations Touching Colours. These five colours were red, yellow, green, blue, and purple.
It was around 1665 when Isaac Newton found the seven colours in the spectrum while he performed experiments with a prism. He added orange to the previous 5 colours and divided the purple into indigo and violet. It is also believed that he only saw 5 colours in the experiment but added two more colours to make the number 7 as this number has a mystical significance. There were seven days in a week, till then only 7 planets were discovered, and most western music has 7 natural notes. So this is the reason behind his analysis of how many colors are in the rainbow.
4. The Science behind the Colors of the Rainbow
As the rainbows are optical illusions they don’t appear in the same spot in the sky. They are only visible to you when they are reflected by the raindrops above the horizon. Since each person views a different horizon and anti-solar point, no one sees the same rainbow.
The light source in natural cases, the sun, is usually behind the person seeing the rainbow. The centre of the rainbow is an anti-solar point and is the exact opposite of the light source. However, the sunlight is visible to your eyes as white light but it is a combination of seven colours that play an important role in the formation. In natural conditions such as rain, fog, sea spray, or waterfall you can see rainbows because of sunlight’s reflection and refraction.
When the sunlight hits the raindrops it gets refracted and reaches the back of the raindrop from where it gets reflected. This reflected light ray then exits the water droplet as it gets refracted into 7 coloured lights. The rainbow arc is formed based on the wavelengths of these lights. The arcs are arranged in order of longest wavelength to shortest wavelength. All these factors are responsible for the answer to how many colors are in the rainbow. (See What Would Happen if There was No Sunlight?)
5. What is Rainbow Color Order?
While watching a rainbow, you must have seen the colors in a rainbow and that they occur in a certain sequence. This sequence is called rainbow color order. Now, this raises another question what decides a rainbow colour order? Well, science does. When sunlight refracts out of the raindrops it is divided into 7 colours as per their wavelengths. The rainbow arc starts with the red light of the longest wavelength and goes till violet light which has the shortest wavelength. Also, check out why does black absorb more heat?
So, the outer arc is made of red light as it has the longest wavelength which is about 650 nanometres. Whereas the inner arc is made up of violet colour light having the shortest wavelength of about 400 nanometers. To ease out remembering the order you can associate it with the acronym ROYGBIV which stands for red, orange, yellow, green, blue, indigo, and violet. These are arranged in the decreasing order of their wavelengths. (Also read What Orders do the Rasta Colors Go In?)
6. Do Rainbows have Pink?
Colors are arranged in the rainbow in order of smallest to longest wavelength. It goes as VIBGYOR and pink color can’t occur in a rainbow. Pink is a combination of red and blue colors. Since red and blue lights in a rainbow are on the opposite ends of the spectrum a rainbow can’t have pink colour. (See Why Are Pink Dolphins Pink?)
7. Is Brown in the Rainbow?
As you already know how many colors are in the rainbow, you must have heard that your eyes are only available to perceive colours that are present in your visual spectrum. Thus you can identify the 7 colors of a rainbow. But when you talk about colours like brown they don’t have their wavelengths for you to see them as they have to be mixed with colours of different wavelengths. The brown colour is a mix of green and red and these two lights are present on opposite ends of the spectrum. Thus color brown being seen in a rainbow is impossible. (See What does Orange and Green make?)
8. Is Purple in the Rainbow?
When the white light refracts through the raindrops or prism it is divided into a multicoloured spectrum. The colour range goes in ascending order of wavelengths where you never see a purple light among these and there is a reason for it. Since red and blue lights are present in opposite directions them mixing up and forming a purple light is not possible. Analyzing things through these scientific parameters is how you decide how many colors are in the rainbow and how many color combinations are impossible. (See What are the top 10 favorite colors?)
9. What does RGB stand for?
If you are into games, tech, lighting or photography you must have heard about the term RGB. It stands for Red Green Blue. It is a very famous colour model and is used in a lot of output devices. It can reproduce an array of colors just by changing the intensities of these three colors namely red, green, and blue. This model is also used to display images on TVs, phones, or computers. A lot of gamers use decorative RGB lighting to enhance the aesthetics of their atmosphere and also their devices. RGB is used in digital printing also. (See What are Coloured Glass Blocks?)
But do you know why this model was developed? It was developed to get closer to the working of the human eye. Your retina is lined up with photosensitive cells that see things in mainly red, green, and blue. Though you are still able to see a variety of colors as your brain mixes these three primary colors to perceive the other colors. (See What are Rubies made of?)
It is quite fascinating to see how things around us in nature are tuned in such amazing ways that they serve as an inspiration for us. Hope all your doubts are cleared up and you like this article about how many colors are in the rainbow. Leave your comments below if you have anything to share with us. (See 16 Snowing in the Mountains Facts)