ELI5: why is the sky blue and space black

// eli5

Why is the sky blue?

The sky looks blue because sunlight bouncing around in our air makes blue light scatter everywhere [2][3]. Think of it like when you shake up a snow globe—the white stuff bounces around and fills the whole globe with whiteness, except here the sun's blue light bounces off air molecules and fills the sky [3].

Why does space look black?

Space is black because there's no air up there to bounce sunlight around [5]. Without air molecules to scatter the light, the sun's rays just zoom straight through and nothing bounces back to our eyes—so it looks completely dark and black [4][5].

Why does blue scatter more than other colors?

Blue light travels in shorter, tinier waves compared to other colors like red [3]. These shorter waves bump into air molecules more easily, so more blue bounces around than any other color [2][3].

What happens at night?

At night, the part of Earth where you are faces away from the sun, so no sunlight comes down to bounce around anymore [4][5]. Without sunlight bouncing in the air, the sky becomes colorless and dark, kind of like how the snow globe looks boring when you stop shaking it [5].