why does the sky appear orange or red at sunset and sunrise

The colors of the sunset or sunrise are the result of the molecules and small particles in the atmosphere changing the direction of the light rays, causing them to disperse to a greater or lesser extent, and this affects the light color.

Explanation:

The colors of the sky are the result of a mixture between the composition of light, the atmosphere and our physiology.

The sunlight is white. That is, it is the sum of all the colors of the rainbow (red, orange, yellow, green, blue and violet).

Travel from the sun to Earth without altering until it enters the atmosphere. Then it collides with the particles that compose it.

So when it has to go through the atmosphere it interacts with the particles, it decomposes and the colors are scattered in all directions. The blue disperses more than the rest giving the sky a violet blue tone. But the cones, photosensitive cells in the retina, are sensitive to blue and eliminate the violet. That's why blue is observed.

But in the position of sunset or dawn the sun's rays travel up to 10 times more atmosphere until it reaches our eyes than when the sun is at the zenith.

Thus, the blue tones suffer such dispersion that they do not reach our eyes while the orange, red and yellow do. The more solid particles that are suspended in the air, the more colorful and saturated are sunsets or sunrises.

In summary, the colors of the sunset or sunrise are the result of the molecules and small particles in the atmosphere changing the direction of the light rays, causing them to disperse to a greater or lesser extent, and this affects the light color.