Why is the sky blue? It's all because of how sunlight interacts with the Earth's atmosphere. The sun sends out light that looks white to us, but it's actually made up of all the colors of the rainbow. When this white light travels through space and reaches our atmosphere, it hits tiny gas molecules, like nitrogen and oxygen.

These molecules are really good at separating blue light. They scatter blue light more than they scatter other colors, like red or yellow. So, the blue light gets scattered in all directions across the sky, making it look blue to our eyes no matter where we look. The other colors of light, like red and yellow, don't get scattered as much and travel in a more direct line to our eyes, which is why the sun looks yellowish.

This effect is called Rayleigh scattering. It was named after the British physicist Lord Rayleigh, who discovered it.