Here's the basic idea:
* Sunlight is made up of all colors of the rainbow.
* Blue light has a shorter wavelength than other colors.
* When sunlight hits the Earth's atmosphere, it interacts with the tiny particles of gas.
* Blue light is scattered more easily by these particles than other colors.
This scattered blue light is what we see as the blue sky.
Of course, the sky can also appear other colors depending on the time of day, weather conditions, and even pollution.
