The prince doesn't seem concerned with answering the pilot's questions, so the pilot has to piece together "things he [says] quite at random" (7)to understand him. The prince, for instance, asks about the pilot's airplane and—after learning that it can fly—questions what planet the pilot is from. Consequently, the pilot realizes that the prince himself must have come from another planet. However, when the pilot asks him about it, the prince simply shakes his head and remarks that the pilot's plane "couldn't have brought [him] from very far" (8).

The prince resumes studying the drawing of the sheep, but the pilot later asks him again about his home planet, and where he will be taking the sheep. The prince says that he's glad to have the crate, since the sheep can sleep in it at night, and the pilot offers to draw a rope to tie the sheep up during the day. This confuses the prince, and he explains that the sheep couldn't go "very far" (8), even if he wandered off. 

The prince's comment about the sheep leads the pilot to realize that his planet is "hardly bigger than a house" (9). The pilot is not actually surprised by this, since he already knew that there are far more small objects in space than full-sized planets, and that "[w]hen an astronomer discovers one of them, he gives it a number instead of a name" (9).