The sky isn't actually made of anything solid. It's a vast expanse of air that surrounds the Earth. Here's a breakdown:

* Atmosphere: The sky is part of the Earth's atmosphere, which is a layer of gases that surrounds our planet.

* Gases: The atmosphere is primarily composed of nitrogen (78%) and oxygen (21%). The remaining 1% includes trace amounts of other gases like carbon dioxide, argon, and neon.

* Light Scattering: The reason we see a blue sky is due to a phenomenon called Rayleigh scattering. When sunlight enters the atmosphere, it interacts with the tiny particles of air. Blue light gets scattered more than other colors, making the sky appear blue to us.

So, the sky isn't made of anything tangible, but it's the result of the interaction of light and the Earth's atmosphere.