In this sequel to the original Cosmos, Carl Sagan again reminds us of the intrinsic human desire to wander, and expands on many of the social and scientific topics discussed in the 1980 television series and accompanying book. Here, Sagan begins with primitive humans migrating across the planet for survival as much as to push the boundaries of a given frontier. From there, Sagan offers a personal anecdote, describing the hardships of his grandparents’ life in Eastern Europe and their fretful immigration to the United States.

A full chapter details the conflicts between science and religion in the early Catholic church and argues that the human race gained a measure of humility after reluctantly accepting the fact that we are not at the center of the universe.  As he did often in Cosmos, Sagan delves into the history of astronomical advancements including early discoveries of the larger moons around Jupiter, Saturn, and Uranus by Galileo, Huygens, Cassini, Kuiper, and Lassell as well as the naming (and renaming) of the first seven planets by the ancients—Earth, Moon, Mercury, Venus, Mars, Jupiter, Saturn—and how this inspired the development of the seven-day calendar week.

Readers are also treated to rich scientific detail about the planets and 60 plus natural satellites in our solar system based on data from the Viking, Galileo, Cassini-Huygens, Pioneers 10 and 11, and Voyager 1 and 2 probes. Further chapters delve into the atmospheric and surface compositions of the worlds, asteroids, and moons before Sagan goes on to expound three major threats to Earth’s environment—ozone depletion, global warming, and nuclear winter.

Sagan’s hopes and visions for the future of manned space exploration through international cooperation are inspiring for all their possibilities, but he is also pragmatic and laments the financial erosion and bureaucratic ossification of the space program over the past three decades and an unfortunate public shift in focus away from planetary exploration. However, in 1994, when Pale Blue Dot was published, it’s difficult to say whether Sagan predicted the dawn of private space agencies—such as SpaceX, Virgin Galactic, Blue Origin, and others—that would fill the void left by the government.

As always, Carl Sagan makes it clear that by exploring other worlds, we open our minds to possibilities far beyond the scope of our limited knowledge and experience bound up on this insignificant pale blue dot situated on the outer edge of a spiral arm lost among billions of stars and planets in the Milky Way.

“We’re made of star stuff. We are a way for the cosmos to know itself.” – Carl Sagan, Cosmos.