A point of view, or the narrative voice, of a text can fall into one of three typical categories: first person, third person omniscient, or third person limited. 

First person is written using the pronouns I, me, my, and mine. The story is the story of the narrator. The narrator tells his or her story from his or her perspective, colored (marked by bias, experience, and point of view) by his or her experiences. 

A third person limited narrator, or point of view, uses the pronouns he, she, they, and them. This narrator knows everything about the protagonist, yet he or she is limited on his or her knowledge of the other characters in the text. This narrative point of view illustrates what the narrator sees regarding the one character he or she "knows" best. 

A third person omniscient narrator is known as the all-knowing/all-seeing narrator. This narrator knows everything about all of the character in the text. 

In the case of Kay Boyle's "Astronomer's Wife," a different narration technique is used. As popularized by Gustave Flaubert's Madame Bovary, Boyle uses a "free indirect style." This style of narration infuses a third person narrator with a first person narrator. What this means is that, at certain times, the narrative voice is that of the traditional third person narrator. At other times, the narrator provides the reader with a much more intimate view of the character's private thoughts. This is accomplished by the narrator personifying the character's internal thoughts.