* No Cells: Stars are not made up of cells, the fundamental building blocks of life. They are giant balls of hot gas, primarily hydrogen and helium.

* No Metabolism: Stars don't have the metabolic processes that living organisms need to survive. They don't consume food, convert energy, or produce waste.

* No Growth or Reproduction: Stars do change over time, but they don't grow or reproduce in the way that living things do.

* No Response to Stimuli: Stars don't react to their environment in the way that living things do.

While stars are incredibly dynamic and undergo fascinating changes, they don't meet the criteria of being considered living.