Why is the sky blue? The answer is more complicated than you think

All the colors that people see are created in different ways. Some of these colors are explained by physics, others by chemistry.

When sunlight passes through the atmosphere, it passes between a lot of those tiny nitrogen and oxygen molecules. Sometimes the light hits one of them directly. That is, the sky looks blue because the blue part of the sunlight is more likely to be reflected from molecules in the atmosphere than other colors of light, explains Daniel Friedman, dean of the College of Science, Technology, Engineering, Mathematics and Management at the University of Wisconsin-Stout, in an article published on The Conversation.

In his explanation, the scientist compares nitrogen molecules to tennis balls, and light to small balls that constantly bounce.

When one of these lightweight balls hits a tennis ball with nitrogen or oxygen, the tennis ball "grabs" the ball and then very quickly returns it back, but in a random direction. This process is called scattering in physics.

The first explanation of sky color

For the first time, the answer to the question "Why is the sky blue?" was found by British physicist John William Strutt in 1870. The blue light from the Sun is scattered the most when it passes through the atmosphere. Thanks to his discovery , the scientific term for this effect is called Rayleigh scattering. That is, if there were no scattering, the sky would be dark, like on the Moon, which has no atmosphere.

The sky is not always blue

Yes, the sky is not always blue, and the Rayleigh scattering effect also has an explanation for why the sky tends to be reddish when the Sun is close to the horizon - at sunrise and sunset.

When the Sun is near the horizon, its light passes through much more of the atmosphere to reach the Earth's surface than when it is directly overhead. Blue and green light is scattered so well that it is almost invisible. Instead, the sky is colored red and orange.

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