"When I heard the learned astronomer" is a poem written by Walt Whitman. The poem is arranged into a single stanza of eight lines and the title is repeated in the first line of it.
The poem is about a narrator who hears a lecture from an astronomer and feels "tired and sick" about it. The narrator then goes outside and sees stars. From this poem, the author may be trying to convey that leaving nature unsolved and mysterious is better than making nature become something systematic and confusing. "When I sitting heard the astronomer where he lectured with much Applause in the lecture-room" This quote means that the narrator was sitting down while other people applauded. The narrator not applauding the astronomer shows that he does not respect what the astronomer was lecturing about. Therefore the narrator does not respect the material that the astronomer was lecturing about such as the proofs, the figures, the charts and the diagrams as mentioned in the poem. And after the narrator goes outside, he sees something he feels that is magnificent and perfect shown with, "looked up in a perfect silence at the stars". The silence shows that the narrator respected nature because he was silent when starring at the stars. The respect the narrator showed towards the astronomer and the stars is clearly a different level of respect. Therefore the poet reveres nature and respects nature while he does not think that making nature systematic is a good thing.

Passing to the structure of the poem, it is composed of free verse. The poem starts with the word when, and the word when is repeated three times after. All the ‘when' words used in the poem is placed at the beginning of the sentence and it is repeated four times, showing the importance of the word.
Those sentences are the sentences that include the astronomer and the things he lectured about.