Why is the Sky Blue

Why is the Sky Blue?  Now You Know!

When you look up to the sky on a clear and sunny day, you see that the sky appears bright blue.  You become mesmerized by its beauty and start to ask yourself why the sky is blue.  But as the day passes and sunset arrives, you look up and see that the bright blue sky has turned into a combination of reds, oranges, and pinks.  Why is that?  What makes the sky blue?

Before we can explain the answer to you, there are some basic things you have to know about the colors of light, light waves and the atmosphere in order to understand the reason why the sky is blue.

Colors of Light

Light is actually composed of several colors, and not just white.  You can see the different colors by using a prism to split the light.  If you don’t have a prism, just look up when you see a rainbow and you can see that light is actually a combination of red, blue, green, yellow, violet, and many more.

All these colors have different frequencies, wavelengths, and energies.  In the visible spectrum, violet has the shortest wavelength, meaning it has the highest frequency along with energy.  Red, on the other hand, has the longest wavelength, lowest frequency and lowest energy.

Light Waves

Light is a type of energy that travels or radiates in waves. Their energy depends on two things: its frequency and its wavelength.  Frequency is the total number of light waves that pass by for every second, while wavelength is the distance amid the crests or tops of the waves.  They are indirectly proportional, meaning the longer the wavelength, the lower the frequency and the less energy it possesses.

Why is the Sky Blue?

They sky is blue because of Rayleigh scattering.  The molecules in the atmosphere scatter the different wavelengths of light coming from the sun.  Air molecules like nitrogen and oxygen molecules reflect those with shorter wavelengths like violet, blue or green much better than the longer wavelengths like red, orange or yellow.  That is why wherever you look in the sky, you can see scattered blue light overhead.

Why is it Red During Sunsets?

When the sun starts to set, light must pass through a greater distance in the atmosphere before it reaches you.  Because of the distance, more of the blue and violet light is being scattered and reflected already, and what reaches to you are those with longer wavelengths like the reds and yellows.  That is why you see a red and orange sky during sunset.

One thought on “Why is the Sky Blue”

  1. Can you guess the color of the sky on moon. It would be black because moon contains no air. What would be the color of saturn sky?

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