Your blue sky patch is a view of light reaching your eyes. The sky is not blue because it reflects a blue ocean.

Sunlight contains different colors. As it passes through the atmosphere, the layer of air around Earth, it meets tiny molecules. Here, a molecule is a tiny particle of a gas.

Molecules scatter light. That means they send it in different directions. They scatter blue light more strongly than red light. Some of that blue light reaches your eyes from the sky around you.

In the milk-water test, look at the liquid from the side of the beam. Then compare light on paper beyond the container. Different colors may appear along those different routes. The liquid is a model for investigating light, not a tiny copy of Earth's air.

Why can the evening sky look different from an earlier blue patch? Near sunset, sunlight takes a longer route through the atmosphere before reaching us.

More blue light gets scattered away from the direct route. The light continuing through can contain a greater share of red and yellow. This helps explain warm sunset colors.

A sunset does not always make a red sky. Clouds, dust and other particles affect what you see. A gray or pale view is still a real observation.

In the milk-water model, catch the light that travels through on white paper. Compare that with the side view. You may see a warmer patch on the paper. Record the actual colors. The comparison invites you to think about different light routes without ever looking at the Sun.