The Common Question of every Child- Why is the Sky Blue?

Have you ever come across this thought that why is the sky blue in colour? Well! This is the most common question asked by any child. In this article we will discuss why does the sky appear in blue colour?

So basically, sky isn’t blue in colour but it is the magic of light from the sun which gets scattered across the earth making the sky appear blue in colour. Although the sunlight looks as if it is white in colour but in scientific explanation this white light is made up of multiple colours of the visible spectrum. The colours may range from red to violet.

What is Raleigh scattering?

When the sunlight is travelling from the sun towards the earth’s atmosphere, it absorbs many elements, particles, colours and compounds. The final colour which is emitted is depended majorly upon the wavelength of the incoming light. The air molecules comprises mainly of nitrogen and oxygen which along with the dust particles play an important role in making the sky appear blue to an human eye.

Impact of colours:

The light emitted from the sun reaches earth in various vertical angles; the wavelengths of light which are shorter tend to absorb violet and blue colours compared to longer wavelengths (red, orange and yellow bands).

These air molecules then radiate the colours violet and blue light in different directions emitting the light in the sky. Due to this, the mid-day sky will look blue in colour rather than the mixture of blue and violet, as our eyes are more sensitive to blue light compared to violet light.

Colour of sky on other planets:

This completely depends on the respective atmosphere of the planet! For instance, planet Mars has very thin atmosphere which is made up of mainly carbon dioxide and fine dust particles. These particles scatter the light very differently when compared to the gases and particles of the Earth.

If you have seen the photos shared by NASA’s rovers and Landers, you can clearly see the opposite sunsets on Martian sky. During the daytime, the sky on the planet Mars appears to be orange or red in colour while the sunsets are usually blue to grey in colour.

Why is the sky red during sunsets on Earth?

When the sun begins to set, the light has to travel further throughout the atmosphere of the Earth. There is no blue light as it gets scattered away but the red light doesn’t get scattered much hence the sky tends to appear red in colour during sunsets and sunrise.

Next time when someone asks you why the sky is blue? You can explain them the Raleigh scattering phenomenon.

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