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Ever Wondered Why The Sky is Blue?

All of Earth's diversity is blanketed under a blue sky. But why? No, it's not a reflection of Earth's oceans and the real explanation requires dipping into a bit of (not particularly complicated) particle physics and a phenomenon known as Rayleigh scattering.

Blue sky above an emerald green hill

In a nutshell, we see blue above us because of how light from the sun interacts with Earth's atmosphere.

Going into a bit more detail, you need to know that the visible light spectrum contains a variety of colors, ranging from red light to violet. When all of the colors are mixed, the light appears white, Marc Chenard, a meteorologist at the U.S. National Weather Service, told Live Science. But once the white light traveling from the sun reaches Earth, some of the colors begin to interact with molecules and small particles in the atmosphere, he said.

Each color in the visible light spectrum has a different wavelength. Red and orange light waves, for instance, have longer wavelengths, while blue and violet light have much shorter wavelengths. It's the shorter wavelengths of light that are more likely to be scattered by the air and gas molecules in Earth's atmosphere, Chenard said. The molecules in the atmosphere, largely nitrogen and oxygen, scatter the blue and violet light in every direction through a phenomenon called Rayleigh scattering.

That's what makes the sky blue.


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