Okay, so first of all, Scene 8 might be my favorite. (But when I write about Scene 2 I might tell you that one is my favorite. Forgive me. I just don't know, you guys).
In this scene, Galileo and his young daughter sit in church, listening to the priest recite Mass. Maria Celeste (her given name was actually Virginia; she became Maria Celeste when she entered the convent) asks Galileo, "Father, what does the Latin say?" Galileo translates for her. "It says, 'Every word of the Bible is sacred, as though descended from heaven.'" The priest continues to deliver the Mass, and Maria Celeste begins, haltingly, to translate the Latin herself. "The Lord laid down the foundations of the earth, that it not be moved forever."
Meanwhile, Galileo has become distracted. As the Mass goes on, Maria Celeste notices the change in the focus of his attention and asks him what he's looking at. "I am looking at the light," he tells her, and then asks her to look up and tell him what she sees. "It's only the chandelier swinging like a pendulum," she answers. He asks her which takes longer, the pendulum swinging a small distance, or a large one, and when she responds -- that presumably it would take the pendulum farther to cover a long distance -- he gently corrects her. No matter how far the pendulum travels, he says, it takes the same amount of time. "But how can you know?" she asks, and he explains that he uses his pulse to time each swing. He comments on the deep and utter perfection of God's world, and remarks that observation of the world is another way of praising the lord.