Why the Sky Appears Blue
The gist
The sky looks blue because sunlight scatters off molecules in the atmosphere, and blue light scatters more than other colors due to its shorter wavelength.
Explain like I'm 5
Imagine sunlight is like a bunch of tiny balls of different colors. The blue balls bounce around more in the air, so when you look up, you see mostly blue.
Big picture
Understanding why the sky is blue helps us learn about how light interacts with our atmosphere, which is important for studying weather, climate, and even how we see colors.