The 8th episode reviews Giovanni Cassini's life. His observations of Saturn and its moons would have an enduring effect on the scientific world. Neil deGrasse Tyson also narrates the mysterious untold story of the scientist who figured out how to go the Moon while fighting for his life in a WWI trench. Aleksandr Shargei changed his name to Yuri Kondratyuk out of fear for his life and wrote a manuscript on rocket motion and space colonization. This letter would end up capturing the attention of an engineer working on the Apollo program, John Houbolt, and would made the Apollo Mission possible.
We will also know the saga of the twenty-year long odyssey of Cassini-Huygens spacecraft, a robotic explorer ordered to commit suicide on another world.

We inhabit a cosmos of undiscovered dimensions and paradoxical realities. We live on one level of perception, but there are others. Every once in a while, a searcher happens upon the doorway to one of these other levels. One of them discovered a paradox about reality that proved to be so profound, we have yet to understand how it could be possible. The universe, or perhaps we should say, universes have never been the same.
In the counterintuitive realm of quantum mechanics, light can be two contradictory things, and somehow - no one knows how - an unseen observer can alter the nature of reality. The man who stumbled on this hole in reality and the still- unfolding technological revolution that it made possible.

Inside the heart of the atom, its nucleus houses energy. This hidden treasure was forged billions of years ago in distant stellar furnaces. The secret of starlight is nothing to fool with. It can bring a civilization to life and it can burn it to the ground.
Two atoms from different parts of the universe meet on a small planet. A deadly embrace between science and state altered the fate of the world and a gripping cautionary tale of others who grew used to living in the shadow of grave danger until it killed them all except one.

When Homo sapiens, which means 'wise ones,' discovered and controlled fire hundreds of thousands of years ago, everything changed. Fire allowed us to cook food and heat dwellings, and it served as a focal point for storytelling and sharing cultural identity among community members. We don't yet have established parameters for what it means to be 'distinctly human,' It would seem the only thing that separates us from other animals, Neil deGrasse Tyson ponders, is our neurotic need to feel 'special'. Against the backdrop of the Halls of Extinction, Tyson insists that there must be a clear distinction between ourselves and animals that justifies our eating them, wearing them and even bringing an end to their species.
From the birth of the devil in ancient Persia to a searing story of saintliness among macaque monkeys, this episode is an exploration of human potential for change. It concludes with the story of how one of history's greatest monsters was transformed into one of its shining lights.

At 11 o'clock on New Year's Eve of the Cosmic Calendar, Homo erectus stood up for the first time, freeing its hands and earning the species its name. They began to move around, to explore, daring to risk everything to get to unknown places. Our Neanderthal relatives lived much as we did and did many of the things we consider to be 'human.' More restless than their cousins the Neanderthals and Denisovans, our Homo sapiens ancestors crossed seas and unforgiving landscapes, changing the land, ocean and atmosphere, leading to mass extinction. The scientific community gave our age a new name, 'Anthropocene.'
Since the first civilizations we've wondered if there's something about human nature that contains the seeds of our destruction. Syukuro Manabe was born in rural Japan and took an intense interest in Earth's average global temperature. In the 1960's, he would assemble the evidence he needed to predict the increase of Earth's temperature due to greenhouse gases until it becomes an uninhabitable and toxic environment, leading to our extinction. 'This doesn't have to be,' says Neil deGrasse Tyson, 'it's not too late. There's another hallway, another future we can still have; we'll find a way.'

The final episode of the series ponders the fate of planet Earth. Neil deGrasse Tyson opens with a reflection on science and those who help us understand it: 'We all feel the weight of the shadows on our future, but in another time, every bit as ominous as our own, there were those who could see a way through the darkness to find a star to steer by.'
The young Carl Sagan and Neil Tyson first discovered their passion for science at the NY World's Fairs of the past. We visit the dazzling Pavilions of the 2039 NY World's Fair, where problems we currently think intractable have been plausibly solved through public commitment and scientific imagination. And our baby is a woman now, with a baby of her own and a future bright with possibilities.