The Backbone of Night is the seventh episode of Cosmos A Personal Voyage. It first aired 9 November 1980 on PBS.
Carl Sagan teaches students in a classroom in his childhood home in Brooklyn, New York. This leads into a history of the different mythologies about stars and the gradual revelation of their true nature. In ancient Greece, some philosophers, such as Aristarchus of Samos, Thales of Miletus, Anaximander, Theodorus of Samos, Empedocles, and Democritus, freely pursue scientific knowledge, while others, including Plato, Aristotle, and the Pythagoreans, advocate slavery and epistemic secrecy.
- Sagan correctly gives the students the prediction that astronomers will confirm the existence of exoplanets within their lifetime.