* No Cells: Living things are made of cells. The sky is a vast expanse of air and gases, not cells.

* No Growth or Reproduction: The sky doesn't grow or reproduce on its own.

* No Metabolism: Living things need energy to function (metabolism). The sky doesn't have its own energy source or metabolic processes.

* No Response to Stimuli: The sky doesn't react to changes in its environment in a way that indicates life.

The sky is a part of the Earth's atmosphere, a mixture of gases that provide us with air to breathe. It's a beautiful and important part of our planet, but it's not alive.