A planet sculpted from cosmic violence. Earth is a very lucky planet. It has ended up the right size and in the right place. This only happened because of violent cosmic collisions. The crazy thing is, if things had been even slightly different, with more or less collisions, we wouldn't be here. We discover the moments that could have destroyed us, but instead made our planet what it is.

Earth gives birth to life. The building blocks of life are common across the universe, but life is rare. What's so special about Earth that it emerged here? Only here on Earth have we found the elixir of life; water in its three forms. But for life to emerge this isn't enough… huge tides created by the proximity of our perfect Moon, plate tectonics, volcanoes and lightning mean the Earth is a dynamic planet. It's a huge planetary chemical experiment, a bubbling cauldron that transforms dead minerals into deoxyribonucleic acid (DNA); the code for all life.

Earth's great paradox. For our planet to become inhabitable for life, you already need life. Ever since life emerged, microbes, plants and animals have all sculpted the planet's surface and air in the strangest of ways; fish poop creates islands; dead animals create mountains; lichen drive continents. But life also has the power to destroy our world. We are changing the climate, but we are not the first to do so. Long before us, microbes froze the planet and almost wiped out all life. The difference between us and them is we are conscious of our actions.

Your brain is an anomaly. We tend to think that once the first life emerged it was inevitable that it would eventually evolve into us. But there is nothing inevitable about consciousness. For over 2 billion years no life on earth possessed a brain. And even today, 90% of life doesn’t have a brain. How life and our strange rock came together to create consciousness is a story of almost impossible and unnecessary coincidences….

There's no place like home. We wrap up the series with the story of NASA's most experienced female astronaut, Peggy Whitson, as she returns home to earth. We might possibly be the only intelligent life in the universe. Life is rare, complex life rarer, and intelligent life may be an evolutionary bad idea or dead end that is rarer still… and that means that it's possible that we humans may be the only thing in this huge and amazing universe that can appreciate its strangeness with awe and wonder.