Look up on a clear day. The sky is blue. Have you ever wondered why? The answer is hiding in the sunlight.

Sunlight looks white. Some people think it is yellow. But it is really made up of all the colors of the rainbow.

A rainbow shows this. When you see one, you are seeing that sunlight is made of many colors.

Light travels in waves. Red light has the longest waves. Blue and violet light have much shorter waves.

The air has tiny bits in it. They are too small to see. They bounce sunlight around the sky.

Blue light has shorter waves than red light. Blue light gets bounced around the sky more than the other colors.

So blue light is bounced all over the sky. That is why the sky looks blue. Red light, with its longer waves, is scattered much less. Near the horizon, the sky fades to a lighter blue or white.

Clouds look white. You may have heard that clouds are white because water is white. In fact, the tiny drops in clouds bounce all the colors of light about equally.

Late in the day, the Sun is low in the sky. Its light has to go through more air to reach your eyes. At sunset the sky turns orange and red.

Never look straight at the Sun. Even dark sunglasses do not make it safe for your eyes.

Words to know

• waves: light moves in
• violet: purple light
• sunset: end of day