For most of the Earth's history, life consisted of the simplest organisms; but then something happened that would give rise to staggering diversity, and, ultimately, life as complex as that which we see today. Scientists are still struggling to figure out just what that was.
2015 • Nature
Earth has a companion in space so large that it rules our nights, our months, our ocean tides. Why Earth should have such a moon is one of the deepest mysteries of the Solar System. We tell the story of how the Earth’s satellite became the unlikely object of desire of the two Cold War superpowers.
The idea of intelligence is explored in the concepts of computers (using bits as their basic units of information), whales (in their songs and their disruptions by human activities), DNA, the human brain (the evolution of the brain stem, frontal lobes, neurons, cerebral hemispheres, and corpus callosum under the Triune Brain Model), and man-made structures for collective intelligence (cities, libraries, books, computers, and satellites). The episode ends with speculation on alien intelligence and the information conveyed on the Voyager Golden Record.
Description of the two Voyager probes sent for interstellar travel. Tyson ends the series by emphasizing Sagan's message on the human condition in the vastness of the cosmos & to encourage viewers to continue to explore and discover the undiscovered.