Sagan’s famous passage describing the “pale blue dot” introduces multiple themes that define the book. But the central thesis of that passage, and perhaps of the book, is that exploration into space will provide humans with enough self-awareness to overcome some of our character flaws. Understanding that Earth is a rare resource and that humanity’s future is not preordained or guaranteed can lead to humans realizing what truly matters. As Sagan writes, “there is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world” (7). For Sagan, the image is one example of the cosmic perspective provided by increased knowledge about the solar system and the Milk Way. The more we learn and the farther we venture into space, the easier it will be to end resource hoarding, war, chauvinism, and willful ignorance on Earth.

Galileo, turning his telescope to Jupiter and finding moons, might have felt a similar clarity regarding the wasted energy spent on Earth discussing Earth as unique, special, and the center of the universe. By looking back at Earth after every discovery in the solar system, and by narrating how often those discoveries have changed our understanding of Earth, Sagan asks the reader to keep an open mind.