Sagan reflects on the future of humanity and the question of 'who speaks for Earth?' when meeting extraterrestrials. He discusses the very different meetings of the Tlingit people and explorer Jean-François de La Perouse with the destruction of the Aztecs by Spanish conquistadors, the looming threat of nuclear warfare, and the threats shown by destruction of the Library of Alexandria and the murder of Hypatia. The episode ends with an overview of the beginning of the universe, the evolution of life, and the accomplishments of humanity and makes a plea to mankind to cherish life and continue its journey in the cosmos. The Cosmos Update notes the preliminary reconnaissance of planets with spacecraft, the fall of the Berlin Wall and the end of apartheid in South Africa, and measures towards the reduction of nuclear weapons.

Each night, across the planet, our cities illuminate the darkness. Their lights burning brighter than ever before. And whilst we're asleep, animals are making the most of this new neon landscape. The sunset in Los Angeles, Chicago, and Toronto creates worlds of opportunities for the cleverest animals willing to take the risk.

This episode takes you on an enchanting journey through the vital waterways of Britain and Ireland. From the serene reed-beds of Somerset to the bustling ecosystems of Scotland's lochs, the film unveils the intricate dance of life sustained by freshwater. Marvel at the agility of dragonflies and the aerial prowess of hobbies, witness the arduous journey of Atlantic salmon as they return to their birthplaces to spawn, and observe the fascinating life cycle of the mayfly. Discover the impact of reintroduced beavers in Scotland, creating new wetlands that buzz with life. The episode doesn't shy away from showcasing the challenges these ecosystems face, from climate change to pollution, emphasizing the delicate balance that sustains these vibrant freshwater habitats.
‘Freshwater’ is a mesmerizing ode to the streams, rivers, and lakes that are the lifeblood of the Britain and Ireland isles, supporting a diverse array of life in one of the planet's most beautiful settings.

Imagine a tornado so powerful, it can form a planet, or winds sweeping across a planet but blowing at 6,000 miles per hour! How about rain....made of iron? Sounds like science fiction, but this type of weather is occurring daily in our solar system. Scientists are just beginning to unlock the secrets of these planets and their atmospheres. Can this research help scientists solve long unanswered questions that we have about Earth? As our own planet churns with the effects of global warming, it's natural to look into the heavens and wonder about the rest of the real estate.

It's a universal dream To soar on wings into the heavens. But it's nothing compared to the reality. Experience our planet as never before: Through the eyes of birds. This is a journey that will embrace the world. A flight across the earth on feathered wings. It's a fantastic voyage following the changing seasons and taking in some of the greatest events on Earth.
Experience a year in the life of our planet from the lush tropics to the frozen North and catch a glimpse of our world as never before: From a bird's-eye view.

Brian considers what it is about our world that makes it a home for life and asks what ingredients were necessary to transform this once barren planet into the Earth we know today? He reveals that it was a rare chain of events combined with the power of life itself that have made Earth unique amongst the cosmos.