Why is the sun red?

It should be said that it will be red sooner or later. The sun is not red, but emits yellow and white light. White light is a mixture of other colors, including red, orange, yellow, green, blue and purple. The wavelength of red light is longer than that of other visible light. Generally speaking, the wave of red light can bypass many dust particles in the air, while other colors are blocked by dust. So it looks red.

There are a lot of dust and tiny water droplets floating in the air, and sunlight is scattered in the atmosphere around the earth (air molecules are also playing a role). Violet light, indigo light and blue light with shorter wavelength scatter greatly and mix together to form a blue sky.

In the early morning and when the sun goes down, the light obliquely passes through the thick atmosphere. In such a long journey, most of the short-wavelength blue light is scattered, and the light that directly enters your eyes is sunlight without blue light. So the sun doesn't look so dazzling, but turns into a big fireball, and the color is orange.