In the second stop in his exploration of the wonders of the universe, Professor Brian Cox goes in search of humanity's very essence to answer the biggest questions of all: what are we? And where do we come from? This film is the story of matter - the stuff of which we are all made. Brian reveals how our origins are entwined with the life cycle of the stars. But he begins his journey here on Earth.

Professor Brian Cox takes on the story of the force that sculpts the entire universe - gravity. It seems so familiar, and yet gravity is one of the strangest and most surprising forces in the universe. In a zero gravity flight, Brian considers how much of an effect gravity has had on the world around us. But gravity also acts over much greater distances. It is the great orchestrator of the cosmos.

Brian Cox seeks to understand the nature of time. From an extraordinary calendar built into the landscape of Peru to the beaches of Costa Rica, Brian explores the cycles of time which define our experience of life on Earth. But as the Earth orbits the Sun, the Solar system orbits the entire Milky Way Galaxy in a cycle that takes a staggering 250 million years to complete.

In the last episode of Professor Brian Cox's epic journey across the universe, he travels from the fossils of the Burgess Shale to the sands of the oldest desert in the world to show how light holds the key to our understanding of the whole universe, including our own deepest origins. But first we need to understand the peculiar properties of light itself.