Then I felt I like some watcher of the skies / when a new planet swims into his ken. This excerpt from on first looking into chapmans homer is an example of a (n)

I would say that "I felt like some watcher of the skies" is comparing something with something else so it looks like a simile though we don't know what is being compared with. though actually the poem by Keats seems to discuss what explorers saw in the time of Cortez so it is related to this,