The sun has seven colors. Why do we see that the sun is red and the sky is blue?

Everything in the world is full of colors, and a colorful world can give us a better experience. In the morning, the sun rises and we see the morning glow all over the sky; Moreover, sunny weather often brings people a good mood. However, have we really thought about the reason why the sun is red and the sky is blue? How did these wonderful phenomena come about?

First, the principle of light propagation Whenever the sun rises in the morning or sets at night, we can always find that the sun emits red light. What is the reason? In fact, sunlight is an electromagnetic wave, which is composed of many different colors of light. In the visible range, we can only see red, orange, yellow, green, cyan, blue and purple. Among the seven kinds of visible light, red light has the longest wavelength and violet light has the shortest wavelength. Moreover, when light propagates in the air, it will scatter. Scattering refers to the penetration of light in the air. Among them, the longer the wavelength, the weaker the light scattering; Conversely, the shorter the wavelength, the stronger the scattering effect of light. So, we can see the red sun and the blue sky.

Second, the formation of red sun and blue sky makes light scatter in the process of propagation. Among them, the air has the weakest scattering effect on red light and the strongest scattering effect on purple light. Therefore, when the sun rises, it needs to pass through the thick atmosphere to be seen by us. At this time, other light with shorter wavelength is scattered by air, and only red light reaches the earth. At this time, the sun we see is red. This phenomenon is especially obvious in foggy days. You can try to observe the colors when the sun rises and sets.

Of course, the formation principle of blue sky is the same. When the sun shines, due to the principle of light scattering, blue light and purple light with shorter wavelength are more likely to diverge in all directions. Besides, it is not easy for our eyes to observe purple light. So, the sky we see is blue.