Here's why:
* Adjectives describe nouns or pronouns. "Visible" describes something that can be seen.
* Verbs show action or a state of being.
Example:
* Visible: The stars were visible in the night sky. (Describing the stars)
* Verb: The stars twinkled brightly. (Showing action)
To use "visible" as a verb, you would need to use it in a different context, such as "to make visible" or "to become visible."