Here's how it works:

* Sunlight: Sunlight is composed of all colors of the rainbow.

* Scattering: When sunlight enters the Earth's atmosphere, it interacts with the molecules of air.

* Rayleigh Scattering: Blue wavelengths of light are scattered more strongly than longer wavelengths (like red) because they are smaller. This is why we see a blue sky.

At sunrise and sunset, the sky appears red or orange because the sunlight has to travel through more of the atmosphere. This means more of the blue light has been scattered away, leaving the longer wavelengths to reach our eyes.