“What men are poets who can speak of Jupiter if he were like a man, but if he is an immense spinning sphere of methane and ammonia must be silent?”
Why pick methane and ammonia of all things? Combined, those make up less than 0.4% (original source page) of the planet by volume. Either by volume or by mass, Jupiter mostly consists of molecular hydrogen.
“What men are poets who can speak of Jupiter if he were like a man, but if he is an immense spinning sphere of methane and ammonia must be silent?” Why pick methane and ammonia of all things? Combined, those make up less than 0.4% (original source page) of the planet by volume. Either by volume or by mass, Jupiter mostly consists of molecular hydrogen.