Given the theme of "when i heard the learn'd astronomer," why does the speaker call the astronomer "learn'd"?
the astronomer is inferior to the speaker because of his academic knowledge.
the astronomer is smarter than the speaker.
the astronomer possesses knowledge that doesn't interest the speaker.
the astronomer and the speaker are equally intelligent

The astronomer possesses knowledge that doesn't interest the speaker.

Explanation:

The reason why the speaker is referring to the astronomer as "learn'd" is because of the high intelligence that manifests in them. The speaker, therefore, uses the astronomer to differentiate between the knowledge that exists between academics and experimental learning. According to the speaker, the lectures and the math formulas are boring because there no connection towards the primary subject matter. But when he looks up at the night sky then there is a different from what one can experience while at the classroom.

if you don't mind posting the paragraph so i could read it that would a lot. (;