The fifth planet is the smallest of these planets, with only enough room for a street lamp and a lamplighter. The little prince muses on the fact that it is rather absurd for a lamplighter to exist on a planet with no people or homes, but he concludes that the lamplighter is less absurd than all the other men he has visited. After all, each time the lamplighter lights the street lamp, it is as if another star is brought into the world, and this is a thing of beauty—and because his job is beautiful, it is truly useful, in the eyes of the little prince.
The little prince asks the lamplighter why he lights and puts out the lamp with such frequency, and the lamplighter responds that these are his orders. He complains that he follows a terrible profession, since his planet has turned faster and faster each year, and now he has no time to rest between lighting and snuffing the lamp. The little prince advises the lamplighter that he need only walk slowly around his planet in order to follow the sun and make the day last longer—but the lamplighter rejects this advice, saying that the one thing he loves in life is to sleep.
The little prince admires the lamplighter's faithfulness—but part of what makes the lamplighter so sad is his lack of desire to explore even the other parts of his planet. He could find some reprieve from his job if he were to walk across his planet, but he's not interested in the walking or exploring, longing only for sleep, which is what he can't have.
The little prince continues on his journey, thinking that the lamplighter is the least ridiculous of the grownups he has met because the lamplighter at least thinks of something other than himself. The little prince regrets that he cannot stay on the planet, as there is no room for two people—he does not admit, however, that he also regrets leaving the planet because it has 1440 sunsets each day.
The little prince has already seen several examples of grownups in his exploring. He believes that the lamplighter has the least ridiculous job because he has a relationship with something other than himself, and this hints at the novella's main lesson about the importance of establishing ties.