In this passage, Nick first observes Gatsby in front of his own house in the dark, and Gatsby stands looking at the "silver pepper of the stars." This figure of speech is a metaphor, a comparison that does not use "like" or "as." This metaphor is particularly striking for the beauty of the image it creates.
It is also a deep metaphor with several layers of meaning, as Nick goes on to say that Gatsby has "come out to determine what share was his of our local heavens." In other words, the use of pepper—something that a person would sprinkle on his or her food—to describe the stars makes it seem as if Gatsby is claiming something that isn't really his to claim. As the reader goes on to discover more about Gatsby, the reader knows that Gatsby tries to buy things to make himself seem more important and that Gatsby lays claim to things and people—even Daisy—that aren't really his to claim. Therefore, this scene, in which Gatsby even tries to measure out and claim the stars, sets a precedent for other objects and people he will try to claim later in the novel.