Why the Wildfire Smoke Makes the Sky Turn Wild Colors

To understand how smoke from Canadian wildfires is turning skies in many places orange this week, it helps to first ask: Why is the sky usually blue?

The scientifically jargony answer: atmospheric scattering.

On the moon and other places where there is no air, the sky is black. But on Earth, we have air, and some light from the sun bounces off the molecules of air in the atmosphere. The higher-energy colors with shorter wavelengths that is, blue light scatter more readily, and as a result, the entire sky is suffused in blue.