>scientists theorized that birds look blue for the same reason the sky looks blue: Red and yellow wavelengths pass through the atmosphere, but shorter blue wave

>scientists theorized that birds look blue for the same reason the sky looks blue: Red and yellow wavelengths pass through the atmosphere, but shorter blue wavelengths bounce off of particles and scatter, emitting a blue glow in every direction. As XKCD has pointed out, there's a complicated physics reason behind every substance's color and the atmosphere isn't special or unusual in that regard. The sky is blue because air is blue.