Henry looks carefully into the telescope which lets him see far, far away, as far away as the distant nebulae on the far edges of the Milky Way ... The Birth of a Star
The above is the first sentence in the story. the writer use the indefinite article (The) three times, I understand one use of them which is last one (the Milky Way) because it is universally known.
Why does the writer use the (not a or nothing) with telescope, nebulae and edges?