Why did the American flag on the moon float?

The "floating" of the national flag on the moon is different from the "floating" blown by the air on the earth.

The national flag planted by Americans on the moon is not a common chemical fiber cloth on the earth, but a special metal material. The national flag made of this material is folded and stored. After being inserted into the surface of the moon and deployed by space flight, the surface of the flag is exposed to the sun. Due to uneven heating everywhere, the flag surface is in an unstable state and swings left and right along the flagpole, which makes observers think it is "floating".

Unstable objects on the fulcrum will swing, and this physical phenomenon will also occur on the earth, but it is different from being "floated" by the wind.